Software Configuration Guide, Cisco IOS Release 15.2(2)E (Catalyst 3750-X and 3560-X Switches)

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Preventing Unauthorized Access

You can prevent unauthorized users from reconfiguring your switch and viewing configuration information. Typically, you want network administrators to have access to your switch while you restrict access to users who dial from outside the network through an asynchronous port, connect from outside the network through a serial port, or connect through a terminal or workstation from within the local network.

To prevent unauthorized access into your switch, you should configure one or more of these security features:

At a minimum, you should configure passwords and privileges at each switch port. These passwords are locally stored on the switch. When users attempt to access the switch through a port or line, they must enter the password specified for the port or line before they can access the switch.
For an additional layer of security, you can also configure username and password pairs, which are locally stored on the switch. These pairs are assigned to lines or ports and authenticate each user before that user can access the switch. If you have defined privilege levels, you can also assign a specific privilege level (with associated rights and privileges) to each username and password pair.
If you want to use username and password pairs, but you want to store them centrally on a server instead of locally, you can store them in a database on a security server. Multiple networking devices can then use the same database to obtain user authentication (and, if necessary, authorization) information.
You can also enable the login enhancements feature, which logs both failed and unsuccessful login attempts. Login enhancements can also be configured to block future login attempts after a set number of unsuccessful attempts are made. For more information, see the Cisco IOS Login Enhancements documentation.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Restrictions for Controlling Switch Access with Passwords and Privileges

The following are the restrictions for controlling switch access with passwords and privileges:

Disabling password recovery will not work if you have set the switch to boot up manually by using the boot manual global configuration command. This command produces the boot loader prompt (switch:) after the switch is power cycled.

Default Password and Privilege Level Configuration

A simple way of providing terminal access control in your network is to use passwords and assign privilege levels. Password protection restricts access to a network or network device. Privilege levels define what commands users can enter after they have logged into a network device.

This table shows the default password and privilege level configuration.

Table 1. Default Password and Privilege Levels
Feature	Default Setting
Enable password and privilege level	No password is defined. The default is level 15 (privileged EXEC level). The password is not encrypted in the configuration file.
Enable secret password and privilege level	No password is defined. The default is level 15 (privileged EXEC level). The password is encrypted before it is written to the configuration file.
Line password	No password is defined.

Additional Password Security

To provide an additional layer of security, particularly for passwords that cross the network or that are stored on a Trivial File Transfer Protocol (TFTP) server, you can use either the enable password or enable secret global configuration commands. Both commands accomplish the same thing; that is, you can establish an encrypted password that users must enter to access privileged EXEC mode (the default) or any privilege level you specify.

We recommend that you use the enable secret command because it uses an improved encryption algorithm.

If you configure the enable secret command, it takes precedence over the enable password command; the two commands cannot be in effect simultaneously.

If you enable password encryption, it applies to all passwords including username passwords, authentication key passwords, the privileged command password, and console and virtual terminal line passwords.

Password Recovery

By default, any end user with physical access to the switch can recover from a lost password by interrupting the boot process while the switch is powering on and then by entering a new password.

The password-recovery disable feature protects access to the switch password by disabling part of this functionality. When this feature is enabled, the end user can interrupt the boot process only by agreeing to set the system back to the default configuration. With password recovery disabled, you can still interrupt the boot process and change the password, but the configuration file (config.text) and the VLAN database file (vlan.dat) are deleted.

If you disable password recovery, we recommend that you keep a backup copy of the configuration file on a secure server in case the end user interrupts the boot process and sets the system back to default values. Do not keep a backup copy of the configuration file on the switch. If the switch is operating in VTP transparent mode, we recommend that you also keep a backup copy of the VLAN database file on a secure server. When the switch is returned to the default system configuration, you can download the saved files to the switch by using the Xmodem protocol.

To re-enable password recovery, use the service password-recovery global configuration command.

Terminal Line Telnet Configuration

When you power-up your switch for the first time, an automatic setup program runs to assign IP information and to create a default configuration for continued use. The setup program also prompts you to configure your switch for Telnet access through a password. If you did not configure this password during the setup program, you can configure it when you set a Telnet password for a terminal line.

Username and Password Pairs

You can configure username and password pairs, which are locally stored on the switch. These pairs are assigned to lines or ports and authenticate each user before that user can access the switch. If you have defined privilege levels, you can also assign a specific privilege level (with associated rights and privileges) to each username and password pair.

Privilege Levels

Cisco switches (and other devices) use privilege levels to provide password security for different levels of switch operation. By default, the Cisco IOS software operates in two modes (privilege levels) of password security: user EXEC (Level 1) and privileged EXEC (Level 15). You can configure up to 16 hierarchical levels of commands for each mode. By configuring multiple passwords, you can allow different sets of users to have access to specified commands.

Privilege Levels on Lines

Users can override the privilege level you set using the privilege level line configuration command by logging in to the line and enabling a different privilege level. They can lower the privilege level by using the disable command. If users know the password to a higher privilege level, they can use that password to enable the higher privilege level. You might specify a high level or privilege level for your console line to restrict line usage.

For example, if you want many users to have access to the clear line command, you can assign it level 2 security and distribute the level 2 password fairly widely. But if you want more restricted access to the configure command, you can assign it level 3 security and distribute that password to a more restricted group of users.

Command Privilege Levels

When you set a command to a privilege level, all commands whose syntax is a subset of that command are also set to that level. For example, if you set the show ip traffic command to level 15, the show commands and show ip commands are automatically set to privilege level 15 unless you set them individually to different levels.

Setting or Changing a Static Enable Password

The enable password controls access to the privileged EXEC mode. Follow these steps to set or change a static enable password:

SUMMARY STEPS

enable
configure terminal
enable password password
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	enable password `password` Example: `Switch(config)# enable password secret321`	Defines a new password or changes an existing password for access to privileged EXEC mode. By default, no password is defined. For `password` , specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. It can contain the question mark (?) character if you precede the question mark with the key combination Crtl-v when you create the password; for example, to create the password abc?123, do this: Enter abc. Enter Crtl-v. Enter ?123. When the system prompts you to enter the enable password, you need not precede the question mark with the Ctrl-v; you can simply enter abc?123 at the password prompt.
Step 4	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 5	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 6	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Protecting Enable and Enable Secret Passwords with Encryption

Follow these steps to establish an encrypted password that users must enter to access privileged EXEC mode (the default) or any privilege level you specify:

SUMMARY STEPS

enable
configure terminal
Use one of the following:

enable password [ level level ] { password | encryption-type encrypted-password }
enable secret [ level level ] { password | encryption-type encrypted-password }

service password-encryption
end
show running-config
copy running-config startup-config

DETAILED STEPS

Command or Action Purpose

Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters the global configuration mode.

Step 3

Use one of the following:

enable password [ level level ] { password | encryption-type encrypted-password }
enable secret [ level level ] { password | encryption-type encrypted-password }

Example:

Switch(config)# enable password example102

or

Switch(config)# enable secret level 1 password secret123sample

Defines a new password or changes an existing password for access to privileged EXEC mode.

Defines a secret password, which is saved using a nonreversible encryption method.

(Optional) For level , the range is from 0 to 15. Level 1 is normal user EXEC mode privileges. The default level is 15 (privileged EXEC mode privileges).
For password , specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.
(Optional) For encryption-type , only type 5, a Cisco proprietary encryption algorithm, is available. If you specify an encryption type, you must provide an encrypted password—an encrypted password that you copy from another switch configuration.

Note

If you specify an encryption type and then enter a clear text password, you can not re-enter privileged EXEC mode. You cannot recover a lost encrypted password by any method.

Step 4

service password-encryption

Example:


Switch(config)# service password-encryption

(Optional) Encrypts the password when the password is defined or when the configuration is written.

Encryption prevents the password from being readable in the configuration file.

Step 5

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Disabling Password Recovery

Follow these steps to disable password recovery to protect the security of your switch:

Before you begin

If you disable password recovery, we recommend that you keep a backup copy of the configuration file on a secure server in case the end user interrupts the boot process and sets the system back to default values. Do not keep a backup copy of the configuration file on the switch. If the switch is operating in VTP transparent mode, we recommend that you also keep a backup copy of the VLAN database file on a secure server. When the switch is returned to the default system configuration, you can download the saved files to the switch by using the Xmodem protocol.

SUMMARY STEPS

enable
configure terminal
system disable password recovery switch {all | <1-9> }
end

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	system disable password recovery switch {`all` \| `<1-9>` } Example: `Switch(config)# system disable password recovery switch all`	Disables password recovery. `all` - Sets the configuration on switches in stack. `<1-9>` - Sets the configuration on the Switch Number selected. This setting is saved in an area of the flash memory that is accessible by the boot loader and the Cisco IOS image, but it is not part of the file system and is not accessible by any user.
Step 4	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.

What to do next

To remove disable password recovery , use the no system disable password recovery switch all global configuration command.

Setting a Telnet Password for a Terminal Line

Beginning in user EXEC mode, follow these steps to set a Telnet password for the connected terminal line:

Before you begin

Attach a PC or workstation with emulation software to the switch console port, or attach a PC to the Ethernet management port.
The default data characteristics of the console port are 9600, 8, 1, no parity. You might need to press the Return key several times to see the command-line prompt.

SUMMARY STEPS

enable
configure terminal
line vty 0 15
password password
end
show running-config
copy running-config startup-config

DETAILED STEPS

Command or Action Purpose

Step 1

enable

Example:


Switch> enable

Note

If a password is required for access to privileged EXEC mode, you will be prompted for it.

Enters privileged EXEC mode.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters the global configuration mode.

Step 3

line vty 0 15

Example:


Switch(config)# line vty 0 15

Configures the number of Telnet sessions (lines), and enters line configuration mode.

There are 16 possible sessions on a command-capable Switch. The 0 and 15 mean that you are configuring all 16 possible Telnet sessions.

Step 4

password password

Example:


Switch(config-line)# password abcxyz543

Sets a Telnet password for the line or lines.

For password , specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.

Step 5

end

Example:


Switch(config-line)# end

Returns to privileged EXEC mode.

Step 6

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring Username and Password Pairs

Follow these steps to configure username and password pairs:

SUMMARY STEPS

enable
configure terminal
username name [privilege level] {password encryption-type password}
Use one of the following:

line console 0
line vty 0 15

login local
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	username `name` [privilege `level`] {password `encryption-type` `password`} Example: `Switch(config)# username adamsample privilege 1 password secret456` `Switch(config)# username 111111111111 mac attribute`	Sets the username, privilege level, and password for each user. For `name` , specify the user ID as one word or the MAC address. Spaces and quotation marks are not allowed. You can configure a maximum of 12000 clients each, for both username and MAC filter. (Optional) For `level` , specify the privilege level the user has after gaining access. The range is 0 to 15. Level 15 gives privileged EXEC mode access. Level 1 gives user EXEC mode access. For `encryption-type` , enter 0 to specify that an unencrypted password will follow. Enter 7 to specify that a hidden password will follow. For `password` , specify the password the user must enter to gain access to the Switch. The password must be from 1 to 25 characters, can contain embedded spaces, and must be the last option specified in the username command.
Step 4	Use one of the following: line console 0 line vty 0 15 Example: `Switch(config)# line console 0` or `Switch(config)# line vty 15`	Enters line configuration mode, and configures the console port (line 0) or the VTY lines (line 0 to 15).
Step 5	login local Example: `Switch(config-line)# login local`	Enables local password checking at login time. Authentication is based on the username specified in Step 3.
Step 6	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 7	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 8	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Setting the Privilege Level for a Command

Follow these steps to set the privilege level for a command:

SUMMARY STEPS

enable
configure terminal
privilege mode level level command
enable password level level password
end
Use one of the following:

show running-config
show privilege

copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	privilege `mode` level `level` `command` Example: `Switch(config)# privilege exec level 14 configure`	Sets the privilege level for a command. For `mode` , enter configure for global configuration mode, exec for EXEC mode, interface for interface configuration mode, or line for line configuration mode. For `level` , the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges. Level 15 is the level of access permitted by the enable password. For `command` , specify the command to which you want to restrict access.
Step 4	enable password level `level` `password` Example: `Switch(config)# enable password level 14 SecretPswd14`	Specifies the password to enable the privilege level. For `level` , the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges. For `password` , specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.
Step 5	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 6	Use one of the following: show running-config show privilege	Verifies your entries. The first command shows the password and access level configuration. The second command shows the privilege level configuration.
Step 7	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Changing the Default Privilege Level for Lines

Follow these steps to change the default privilege level for the specified line:

SUMMARY STEPS

enable
configure terminal
line vty line
privilege level level
end
Use one of the following:

show running-config
show privilege

copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	line vty `line` Example: `Switch(config)# line vty 10`	Selects the virtual terminal line on which to restrict access.
Step 4	privilege level `level` Example: `Switch(config)# privilege level 15`	Changes the default privilege level for the line. For `level` , the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges. Level 15 is the level of access permitted by the enable password.
Step 5	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 6	Use one of the following: show running-config show privilege Example: `Switch# show running-config` or `Switch# show privilege`	Verifies your entries. The first command shows the password and access level configuration. The second command shows the privilege level configuration.
Step 7	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

What to do next

Users can override the privilege level you set using the privilege level line configuration command by logging in to the line and enabling a different privilege level. They can lower the privilege level by using the disable command. If users know the password to a higher privilege level, they can use that password to enable the higher privilege level. You might specify a high level or privilege level for your console line to restrict line usage.

Logging into and Exiting a Privilege Level

Beginning in user EXEC mode, follow these steps to log into a specified privilege level and exit a specified privilege level.

SUMMARY STEPS

enable level
disable level

DETAILED STEPS

Command or Action Purpose

	Command or Action	Purpose
Step 1	enable `level` Example: `Switch> enable 15`	Logs in to a specified privilege level. Following the example, Level 15 is privileged EXEC mode. For `level` , the range is 0 to 15.
Step 2	disable `level` Example: `Switch# disable 1`	Exits to a specified privilege level. Following the example, Level 1 is user EXEC mode. For `level` , the range is 0 to 15.

Step 1

enable level

Example:


Switch> enable 15

Logs in to a specified privilege level.

Following the example, Level 15 is privileged EXEC mode.

For level , the range is 0 to 15.

Step 2

disable level

Example:


Switch# disable 1

Exits to a specified privilege level.

Following the example, Level 1 is user EXEC mode.

For level , the range is 0 to 15.

Monitoring Switch Access

Table 2. Commands for Displaying DHCP Information

show privilege	Displays the privilege level configuration.

Example: Setting or Changing a Static Enable Password

This example shows how to change the enable password to l1u2c3k4y5. The password is not encrypted and provides access to level 15 (traditional privileged EXEC mode access):


Switch(config)# enable password l1u2c3k4y5

Example: Protecting Enable and Enable Secret Passwords with Encryption

This example shows how to configure the encrypted password $1$FaD0$Xyti5Rkls3LoyxzS8 for privilege level 2:


Switch(config)# enable secret level 2 5 $1$FaD0$Xyti5Rkls3LoyxzS8

Example: Setting a Telnet Password for a Terminal Line

This example shows how to set the Telnet password to let45me67in89:


Switch(config)# line vty 10
Switch(config-line)# password let45me67in89

Example: Setting the Privilege Level for a Command

This example shows how to set the configure command to privilege level 14 and define SecretPswd14 as the password users must enter to use level 14 commands:


Switch(config)# privilege exec level 14 configure
Switch(config)# enable password level 14 SecretPswd14

Additional References

Error Message Decoder


Description	Link
To help you research and resolve system error messages in this release, use the Error Message Decoder tool.	https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi

MIBs


MIB	MIBs Link
	To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

Technical Assistance


Description	Link
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.	http://www.cisco.com/support

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Controlling Switch Access with Terminal Access Controller Access Control System Plus (TACACS+)

The following are the prerequisites for set up and configuration of switch access with Terminal Access Controller Access Control System Plus (TACACS+) (must be performed in the order presented):

Configure the switches with the TACACS+ server addresses.
Set an authentication key.
Configure the key from Step 2 on the TACACS+ servers.
Enable AAA.
Create a login authentication method list.
Apply the list to the terminal lines.
Create an authorization and accounting method list.

The following are the prerequisites for controlling switch access with TACACS+:

You must have access to a configured TACACS+ server to configure TACACS+ features on your switch. Also, you must have access to TACACS+ services maintained in a database on a TACACS+ daemon typically running on a LINUX or Windows workstation.
We recommend a redundant connection between a switch stack and the TACACS+ server. This is to help ensure that the TACACS+ server remains accessible in case one of the connected stack members is removed from the switch stack.
You need a system running the TACACS+ daemon software to use TACACS+ on your switch.
To use TACACS+, it must be enabled.
Authorization must be enabled on the switch to be used.
Users must first successfully complete TACACS+ authentication before proceeding to TACACS+ authorization.
To use any of the AAA commands listed in this section or elsewhere, you must first enable AAA with the aaa new-model command.
At a minimum, you must identify the host or hosts maintaining the TACACS+ daemon and define the method lists for TACACS+ authentication. You can optionally define method lists for TACACS+ authorization and accounting.
The method list defines the types of authentication to be performed and the sequence in which they are performed; it must be applied to a specific port before any of the defined authentication methods are performed. The only exception is the default method list (which, by coincidence, is named default ). The default method list is automatically applied to all ports except those that have a named method list explicitly defined. A defined method list overrides the default method list.
Use TACACS+ for privileged EXEC access authorization if authentication was performed by using TACACS+.
Use the local database if authentication was not performed by using TACACS+.

TACACS+ and Switch Access

This section describes TACACS+. TACACS+ provides detailed accounting information and flexible administrative control over the authentication and authorization processes. It is facilitated through authentication, authorization, accounting (AAA) and can be enabled only through AAA commands.

TACACS+ Overview

TACACS+ is a security application that provides centralized validation of users attempting to gain access to your switch.

TACACS+ services are maintained in a database on a TACACS+ daemon typically running on a LINUX or Windows workstation. You should have access to and should configure a TACACS+ server before you configure TACACS+ features on your switch.

TACACS+ provides for separate and modular authentication, authorization, and accounting facilities. TACACS+ allows for a single access control server (the TACACS+ daemon) to provide each service—authentication, authorization, and accounting—independently. Each service can be tied into its own database to take advantage of other services available on that server or on the network, depending on the capabilities of the daemon.

The goal of TACACS+ is to provide a method for managing multiple network access points from a single management service. Your switch can be a network access server along with other Cisco routers and access servers.

Figure 1. Typical TACACS+ Network Configuration

TACACS+, administered through the AAA security services, can provide these services:

Authentication—Provides complete control of authentication through login and password dialog, challenge and response, and messaging support.

The authentication facility can conduct a dialog with the user (for example, after a username and password are provided, to challenge a user with several questions, such as home address, mother’s maiden name, service type, and social security number). The TACACS+ authentication service can also send messages to user screens. For example, a message could notify users that their passwords must be changed because of the company’s password aging policy.
Authorization—Provides fine-grained control over user capabilities for the duration of the user’s session, including but not limited to setting autocommands, access control, session duration, or protocol support. You can also enforce restrictions on what commands a user can execute with the TACACS+ authorization feature.
Accounting—Collects and sends information used for billing, auditing, and reporting to the TACACS+ daemon. Network managers can use the accounting facility to track user activity for a security audit or to provide information for user billing. Accounting records include user identities, start and stop times, executed commands (such as PPP), number of packets, and number of bytes.

The TACACS+ protocol provides authentication between the switch and the TACACS+ daemon, and it ensures confidentiality because all protocol exchanges between the switch and the TACACS+ daemon are encrypted.

TACACS+ Operation

When a user attempts a simple ASCII login by authenticating to a switch using TACACS+, this process occurs:

When the connection is established, the switch contacts the TACACS+ daemon to obtain a username prompt to show to the user. The user enters a username, and the switch then contacts the TACACS+ daemon to obtain a password prompt. The switch displays the password prompt to the user, the user enters a password, and the password is then sent to the TACACS+ daemon.

TACACS+ allows a dialog between the daemon and the user until the daemon receives enough information to authenticate the user. The daemon prompts for a username and password combination, but can include other items, such as the user’s mother’s maiden name.
The switch eventually receives one of these responses from the TACACS+ daemon:
- ACCEPT—The user is authenticated and service can begin. If the switch is configured to require authorization, authorization begins at this time.
- REJECT—The user is not authenticated. The user can be denied access or is prompted to retry the login sequence, depending on the TACACS+ daemon.
- ERROR—An error occurred at some time during authentication with the daemon or in the network connection between the daemon and the switch. If an ERROR response is received, the switch typically tries to use an alternative method for authenticating the user.
- CONTINUE—The user is prompted for additional authentication information.
After authentication, the user undergoes an additional authorization phase if authorization has been enabled on the switch. Users must first successfully complete TACACS+ authentication before proceeding to TACACS+ authorization.
If TACACS+ authorization is required, the TACACS+ daemon is again contacted, and it returns an ACCEPT or REJECT authorization response. If an ACCEPT response is returned, the response contains data in the form of attributes that direct the EXEC or NETWORK session for that user and the services that the user can access:
- Telnet, Secure Shell (SSH), rlogin, or privileged EXEC services
- Connection parameters, including the host or client IP address, access list, and user timeouts

TACACS+ Configuration Options

You can configure the switch to use a single server or AAA server groups to group existing server hosts for authentication. You can group servers to select a subset of the configured server hosts and use them for a particular service. The server group is used with a global server-host list and contains the list of IP addresses of the selected server hosts.

TACACS+ Login Authentication

A method list describes the sequence and authentication methods to be queried to authenticate a user. You can designate one or more security protocols to be used for authentication, thus ensuring a backup system for authentication in case the initial method fails. The software uses the first method listed to authenticate users; if that method fails to respond, the software selects the next authentication method in the method list. This process continues until there is successful communication with a listed authentication method or until all defined methods are exhausted. If authentication fails at any point in this cycle—meaning that the security server or local username database responds by denying the user access—the authentication process stops, and no other authentication methods are attempted.

TACACS+ Authorization for Privileged EXEC Access and Network Services

AAA authorization limits the services available to a user. When AAA authorization is enabled, the switch uses information retrieved from the user’s profile, which is located either in the local user database or on the security server, to configure the user’s session. The user is granted access to a requested service only if the information in the user profile allows it.

TACACS+ Accounting

The AAA accounting feature tracks the services that users are accessing and the amount of network resources that they are consuming. When AAA accounting is enabled, the switch reports user activity to the TACACS+ security server in the form of accounting records. Each accounting record contains accounting attribute-value (AV) pairs and is stored on the security server. This data can then be analyzed for network management, client billing, or auditing.

Default TACACS+ Configuration

TACACS+ and AAA are disabled by default.

To prevent a lapse in security, you cannot configure TACACS+ through a network management application. When enabled, TACACS+ can authenticate users accessing the switch through the CLI.

Note

Although TACACS+ configuration is performed through the CLI, the TACACS+ server authenticates HTTP connections that have been configured with a privilege level of 15.

Identifying the TACACS+ Server Host and Setting the Authentication Key

Follow these steps to identify the TACACS+ server host and set the authentication key:

SUMMARY STEPS

enable
configure terminal
tacacs-server host hostname [port integer] [timeout integer] [key string]
aaa new-model
aaa group server tacacs+ group-name
server ip-address
end
show tacacs
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	tacacs-server host `hostname` [port `integer`] [timeout `integer`] [key `string`] Example: `Switch(config)# tacacs-server host yourserver port 23 timeout 3 key your_key`	Identifies the IP host or hosts maintaining a TACACS+ server. Enter this command multiple times to create a list of preferred hosts. The software searches for hosts in the order in which you specify them. For `hostname` , specify the name or IP address of the host. (Optional) For port `integer` , specify a server port number. The default is port 49. The range is 1 to 65535. (Optional) For timeout `integer` , specify a time in seconds the switch waits for a response from the daemon before it times out and declares an error. The default is 5 seconds. The range is 1 to 1000 seconds. (Optional) For key `string` , specify the encryption key for encrypting and decrypting all traffic between the switch and the TACACS+ daemon. You must configure the same key on the TACACS+ daemon for encryption to be successful.
Step 4	aaa new-model Example: `Switch(config)# aaa new-model`	Enables AAA.
Step 5	aaa group server tacacs+ `group-name` Example: `Switch(config)# aaa group server tacacs+ your_server_group`	(Optional) Defines the AAA server-group with a group name. This command puts the Switch in a server group subconfiguration mode.
Step 6	server `ip-address` Example: `Switch(config)# server 10.1.2.3`	(Optional) Associates a particular TACACS+ server with the defined server group. Repeat this step for each TACACS+ server in the AAA server group. Each server in the group must be previously defined in Step 3.
Step 7	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 8	show tacacs Example: `Switch# show tacacs`	************************************ This command displays no output. Is it supposed to? ************************************ Verifies your entries.
Step 9	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 10	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Configuring TACACS+ Login Authentication

Follow these steps to configure TACACS+ login authentication:

Before you begin

To configure AAA authentication, you define a named list of authentication methods and then apply that list to various ports.

Note

To secure the switch for HTTP access by using AAA methods, you must configure the switch with the ip http authentication aaa global configuration command. Configuring AAA authentication does not secure the switch for HTTP access by using AAA methods.

For more information about the ip http authentication command, see the Cisco IOS Security Command Reference, Release 12.4.

SUMMARY STEPS

enable
configure terminal
aaa new-model
aaa authentication login {default | list-name} method1 [method2...]
line [console | tty | vty ] line-number [ending-line-number]
login authentication {default | list-name}
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	aaa new-model Example: `Switch(config)# aaa new-model`	Enables AAA.
Step 4	aaa authentication login {default \| `list-name`} `method1` [`method2...`] Example: `Switch(config)# aaa authentication login default tacacs+ local`	Creates a login authentication method list. To create a default list that is used when a named list is not specified in the login authentication command, use the default keyword followed by the methods that are to be used in default situations. The default method list is automatically applied to all ports. For `list-name` , specify a character string to name the list you are creating. For `method1...` , specify the actual method the authentication algorithm tries. The additional methods of authentication are used only if the previous method returns an error, not if it fails. Select one of these methods: `enable` —Use the enable password for authentication. Before you can use this authentication method, you must define an enable password by using the enable `password` global configuration command. `group tacacs+` —Uses TACACS+ authentication. Before you can use this authentication method, you must configure the TACACS+ server. `line` —Use the line password for authentication. Before you can use this authentication method, you must define a line password. Use the password `password` line configuration command. `local` —Use the local username database for authentication. You must enter username information in the database. Use the username `password` global configuration command. `local-case` —Use a case-sensitive local username database for authentication. You must enter username information in the database by using the username `name` password global configuration command. `none` —Do not use any authentication for login.
Step 5	line [console \| tty \| vty ] `line-number` [`ending-line-number`] Example: `Switch(config)# line 2 4`	Enters line configuration mode, and configures the lines to which you want to apply the authentication list.
Step 6	login authentication {default \| `list-name`} Example: `Switch(config-line)# login authentication default`	Applies the authentication list to a line or set of lines. If you specify default , use the default list created with the aaa authentication login command. For `list-name` , specify the list created with the aaa authentication login command.
Step 7	end Example: `Switch(config-line)# end`	Returns to privileged EXEC mode.
Step 8	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 9	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Configuring TACACS+ Authorization for Privileged EXEC Access and Network Services

You can use the aaa authorization global configuration command with the tacacs+ keyword to set parameters that restrict a user’s network access to privileged EXEC mode.

Note

Authorization is bypassed for authenticated users who log in through the CLI even if authorization has been configured.

Follow these steps to specify TACACS+ authorization for privileged EXEC access and network services:

SUMMARY STEPS

enable
configure terminal
aaa authorization network tacacs+
aaa authorization exec tacacs+
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	aaa authorization network tacacs+ Example: `Switch(config)# aaa authorization network tacacs+`	Configures the switch for user TACACS+ authorization for all network-related service requests.
Step 4	aaa authorization exec tacacs+ Example: `Switch(config)# aaa authorization exec tacacs+`	Configures the switch for user TACACS+ authorization if the user has privileged EXEC access. The exec keyword might return user profile information (such as autocommand information).
Step 5	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 6	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 7	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Starting TACACS+ Accounting

Follow these steps to start TACACS+ Accounting:

SUMMARY STEPS

enable
configure terminal
aaa accounting network start-stop tacacs+
aaa accounting exec start-stop tacacs+
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	aaa accounting network start-stop tacacs+ Example: `Switch(config)# aaa accounting network start-stop tacacs+`	Enables TACACS+ accounting for all network-related service requests.
Step 4	aaa accounting exec start-stop tacacs+ Example: `Switch(config)# aaa accounting exec start-stop tacacs+`	Enables TACACS+ accounting to send a start-record accounting notice at the beginning of a privileged EXEC process and a stop-record at the end.
Step 5	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 6	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 7	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

What to do next

To establish a session with a router if the AAA server is unreachable, use the aaa accounting system guarantee-first command. It guarantees system accounting as the first record, which is the default condition. In some situations, users might be prevented from starting a session on the console or terminal connection until after the system reloads, which can take more than 3 minutes.

To establish a console or Telnet session with the router if the AAA server is unreachable when the router reloads, use the no aaa accounting system guarantee-first command.

Establishing a Session with a Router if the AAA Server is Unreachable

To establishing a session with a router if the AAA server is unreachable, use the aaa accounting system guarantee-first command. It guarantees system accounting as the first record, which is the default condition. In some situations, users might be prevented from starting a session on the console or terminal connection until after the system reloads, which can take more than 3 minutes.

To establish a console or Telnet session with the router if the AAA server is unreachable when the router reloads, use the no aaa accounting system guarantee-first command.

Monitoring TACACS+

Table 3. Commands for Displaying TACACS+ Information
Command	Purpose
show tacacs	Displays TACACS+ server statistics.

Additional References

Related Topic	Document Title
“TACACS+ Over an IPv6 Transport” section of the “Implementing ADSL for IPv6” chapter	Cisco IOS XE IPv6 Configuration Guide, Release 2
Configuring TACACS+ over IPv6” section of the “Implementing ADSL for IPv6” chapter	Cisco IOS XE IPv6 Configuration Guide, Release 2
TACACS+ commands	Cisco IOS IPv6 Command Reference

MIBs


MIB	MIBs Link
	To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

Technical Assistance


Description	Link
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.	http://www.cisco.com/support

Feature Information for TACACS+


Release	Feature Information
Cisco IOS 12.2(58)SE	TACACS+ support for IPv6.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Controlling Switch Access with RADIUS

This section lists the prerequisites for controlling Switch access with RADIUS.

General:

RADIUS and AAA must be enabled to use any of the configuration commands in this chapter.
RADIUS is facilitated through AAA and can be enabled only through AAA commands.
At a minimum, you must identify the host or hosts that run the RADIUS server software and define the method lists for RADIUS authentication. You can optionally define method lists for RADIUS authorization and accounting.
You should have access to and should configure a RADIUS server before configuring RADIUS features on your Switch.
The RADIUS host is normally a multiuser system running RADIUS server software from Cisco (Cisco Secure Access Control Server Version 3.0), Livingston, Merit, Microsoft, or another software provider. For more information, see the RADIUS server documentation.
To use the Change-of-Authorization (CoA) interface, a session must already exist on the switch. CoA can be used to identify a session and enforce a disconnect request. The update affects only the specified session.
A redundant connection between a switch stack and the RADIUS server is recommended. This is to help ensure that the RADIUS server remains accessible in case one of the connected stack members is removed from the switch stack.

For RADIUS operation:

Users must first successfully complete RADIUS authentication before proceeding to RADIUS authorization, if it is enabled.

Restrictions for Controlling Switch Access with RADIUS

This topic covers restrictions for controlling Switch access with RADIUS.

General:

To prevent a lapse in security, you cannot configure RADIUS through a network management application.

RADIUS is not suitable in the following network security situations:

Multiprotocol access environments. RADIUS does not support AppleTalk Remote Access (ARA), NetBIOS Frame Control Protocol (NBFCP), NetWare Asynchronous Services Interface (NASI), or X.25 PAD connections.
Switch-to-switch or router-to-router situations. RADIUS does not provide two-way authentication. RADIUS can be used to authenticate from one device to a non-Cisco device if the non-Cisco device requires authentication.
Networks using a variety of services. RADIUS generally binds a user to one service model.

RADIUS and Switch Access

This section describes how to enable and configure RADIUS. RADIUS provides detailed accounting information and flexible administrative control over the authentication and authorization processes.

RADIUS Overview

RADIUS is a distributed client/server system that secures networks against unauthorized access. RADIUS clients run on supported Cisco routers and switches. Clients send authentication requests to a central RADIUS server, which contains all user authentication and network service access information.

Use RADIUS in these network environments that require access security:

Networks with multiple-vendor access servers, each supporting RADIUS. For example, access servers from several vendors use a single RADIUS server-based security database. In an IP-based network with multiple vendors’ access servers, dial-in users are authenticated through a RADIUS server that has been customized to work with the Kerberos security system.
Turnkey network security environments in which applications support the RADIUS protocol, such as in an access environment that uses a smart card access control system. In one case, RADIUS has been used with Enigma’s security cards to validates users and to grant access to network resources.
Networks already using RADIUS. You can add a Cisco Switch containing a RADIUS client to the network. This might be the first step when you make a transition to a TACACS+ server. See Figure 2: Transitioning from RADIUS to TACACS+ Services below.
Network in which the user must only access a single service. Using RADIUS, you can control user access to a single host, to a single utility such as Telnet, or to the network through a protocol such as IEEE 802.1x. For more information about this protocol, see Chapter 11, “Configuring IEEE 802.1x Port-Based Authentication.”
Networks that require resource accounting. You can use RADIUS accounting independently of RADIUS authentication or authorization. The RADIUS accounting functions allow data to be sent at the start and end of services, showing the amount of resources (such as time, packets, bytes, and so forth) used during the session. An Internet service provider might use a freeware-based version of RADIUS access control and accounting software to meet special security and billing needs.

Figure 2. Transitioning from RADIUS to TACACS+ Services

RADIUS Operation

When a user attempts to log in and authenticate to a Switch that is access controlled by a RADIUS server, these events occur:

The user is prompted to enter a username and password.
The username and encrypted password are sent over the network to the RADIUS server.
The user receives one of the following responses from the RADIUS server:
- ACCEPT—The user is authenticated.
- REJECT—The user is either not authenticated and is prompted to re-enter the username and password, or access is denied.
- CHALLENGE—A challenge requires additional data from the user.
- CHALLENGE PASSWORD—A response requests the user to select a new password.
The ACCEPT or REJECT response is bundled with additional data that is used for privileged EXEC or network authorization. The additional data included with the ACCEPT or REJECT packets includes these items:

Telnet, SSH, rlogin, or privileged EXEC services
Connection parameters, including the host or client IP address, access list, and user timeouts

RADIUS Change of Authorization

This section provides an overview of the RADIUS interface including available primitives and how they are used during a Change of Authorization (CoA).

Change-of-Authorization Requests
CoA Request Response Code
CoA Request Commands
Session Reauthentication
Stacking Guidelines for Session Termination

A standard RADIUS interface is typically used in a pulled model where the request originates from a network attached device and the response come from the queried servers. Catalyst switches support the RADIUS Change of Authorization (CoA) extensions defined in RFC 5176 that are typically used in a pushed model and allow for the dynamic reconfiguring of sessions from external authentication, authorization, and accounting (AAA) or policy servers.

The switch supports these per-session CoA requests:

Session reauthentication
Session termination
Session termination with port shutdown
Session termination with port bounce

This feature is integrated with Cisco Identity Services Engine, and Cisco Secure Access Control Server (ACS) 5.1.

The RADIUS interface is enabled by default on Catalyst switches. However, some basic configuration is required for the following attributes:

Security and Password—refer to the “Preventing Unauthorized Access to Your Switch” section in this guide.
Accounting—refer to the “Starting RADIUS Accounting” section in the Configuring Switch-Based Authentication chapter in this guide.

Change-of-Authorization Requests

Change of Authorization (CoA) requests, as described in RFC 5176, are used in a push model to allow for session identification, host reauthentication, and session termination. The model is comprised of one request (CoA-Request) and two possible response codes:

CoA acknowledgment (ACK) [CoA-ACK]
CoA non-acknowledgment (NAK) [CoA-NAK]

The request is initiated from a CoA client (typically a RADIUS or policy server) and directed to the switch that acts as a listener.

RFC 5176 Compliance

The Disconnect Request message, which is also referred to as Packet of Disconnect (POD), is supported by the switch for session termination.

This table shows the IETF attributes are supported for this feature.

Table 4. Supported IETF Attributes
Attribute Number	Attribute Name
24	State
31	Calling-Station-ID
44	Acct-Session-ID
80	Message-Authenticator
101	Error-Cause

This table shows the possible values for the Error-Cause attribute.

Table 5. Error-Cause Values
Value	Explanation
201	Residual Session Context Removed
202	Invalid EAP Packet (Ignored)
401	Unsupported Attribute
402	Missing Attribute
403	NAS Identification Mismatch
404	Invalid Request
405	Unsupported Service
406	Unsupported Extension
407	Invalid Attribute Value
501	Administratively Prohibited
502	Request Not Routable (Proxy)
503	Session Context Not Found
504	Session Context Not Removable
505	Other Proxy Processing Error
506	Resources Unavailable
507	Request Initiated
508	Multiple Session Selection Unsupported

CoA Request Response Code

The CoA Request response code can be used to convey a command to the switch.

Session Identification

For disconnect and CoA requests targeted at a particular session, the switch locates the session based on one or more of the following attributes:

Calling-Station-Id (IETF attribute #31 which contains the host MAC address)
Audit-Session-Id (Cisco VSA)
Acct-Session-Id (IETF attribute #44)

Unless all session identification attributes included in the CoA message match the session, the switch returns a Disconnect-NAK or CoA-NAK with the “Invalid Attribute Value” error-code attribute.

If more than one session identification attribute is included in the message, all the attributes must match the session or the switch returns a Disconnect- negative acknowledgment (NAK) or CoA-NAK with the error code “Invalid Attribute Value.”

The packet format for a CoA Request code as defined in RFC 5176 consists of the fields: Code, Identifier, Length, Authenticator, and Attributes in Type:Length:Value (TLV) format.



    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Code      |  Identifier   |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                         Authenticator                         |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Attributes ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-

The attributes field is used to carry Cisco vendor-specific attributes (VSAs).

CoA ACK Response Code

If the authorization state is changed successfully, a positive acknowledgment (ACK) is sent. The attributes returned within CoA ACK will vary based on the CoA Request and are discussed in individual CoA Commands.

CoA NAK Response Code

A negative acknowledgment (NAK) indicates a failure to change the authorization state and can include attributes that indicate the reason for the failure. Use show commands to verify a successful CoA.

CoA Request Commands

Table 6. CoA Commands Supported on the switch
Command ¹	Cisco VSA
Reauthenticate host	Cisco:Avpair=“subscriber:command=reauthenticate”
Terminate session	This is a standard disconnect request that does not require a VSA.
Bounce host port	Cisco:Avpair=“subscriber:command=bounce-host-port”
Disable host port	Cisco:Avpair=“subscriber:command=disable-host-port”

¹ All CoA commands must include the session identifier between the switch and the CoA client.

Session Reauthentication

The AAA server typically generates a session reauthentication request when a host with an unknown identity or posture joins the network and is associated with a restricted access authorization profile (such as a guest VLAN). A reauthentication request allows the host to be placed in the appropriate authorization group when its credentials are known.

To initiate session authentication, the AAA server sends a standard CoA-Request message which contains a Cisco VSA in this form: Cisco:Avpair=“subscriber:command=reauthenticate” and one or more session identification attributes.

The current session state determines the switch response to the message. If the session is currently authenticated by IEEE 802.1x, the switch responds by sending an EAPoL (Extensible Authentication Protocol over Lan) -RequestId message to the server.

If the session is currently authenticated by MAC authentication bypass (MAB), the switch sends an access-request to the server, passing the same identity attributes used for the initial successful authentication.

If session authentication is in progress when the switch receives the command, the switch terminates the process, and restarts the authentication sequence, starting with the method configured to be attempted first.

If the session is not yet authorized, or is authorized via guest VLAN, or critical VLAN, or similar policies, the reauthentication message restarts the access control methods, beginning with the method configured to be attempted first. The current authorization of the session is maintained until the reauthentication leads to a different authorization result.

Session Reauthentication in a Switch Stack

When a switch stack receives a session reauthentication message:

It checkpoints the need for a re-authentication before returning an acknowledgment (ACK).
It initiates reauthentication for the appropriate session.
If authentication completes with either success or failure, the signal that triggered the reauthentication is removed from the stack member.
If the stack master fails before authentication completes, reauthentication is initiated after stack master switch-over based on the original command (which is subsequently removed).
If the stack master fails before sending an ACK, the new stack master treats the re-transmitted command as a new command.

Session Termination

There are three types of CoA requests that can trigger session termination. A CoA Disconnect-Request terminates the session, without disabling the host port. This command causes re-initialization of the authenticator state machine for the specified host, but does not restrict that host’s access to the network.

To restrict a host’s access to the network, use a CoA Request with the Cisco:Avpair="subscriber:command=disable-host-port" VSA. This command is useful when a host is known to be causing problems on the network, and you need to immediately block network access for the host. When you want to restore network access on the port, re-enable it using a non-RADIUS mechanism.

When a device with no supplicant, such as a printer, needs to acquire a new IP address (for example, after a VLAN change), terminate the session on the host port with port-bounce (temporarily disable and then re-enable the port).

CoA Disconnect-Request

This command is a standard Disconnect-Request. If the session cannot be located, the switch returns a Disconnect-NAK message with the “Session Context Not Found” error-code attribute. If the session is located, the switch terminates the session. After the session has been completely removed, the switch returns a Disconnect-ACK.

If the switch fails-over to a standby switch before returning a Disconnect-ACK to the client, the process is repeated on the new active switch when the request is re-sent from the client. If the session is not found following re-sending, a Disconnect-ACK is sent with the “Session Context Not Found” error-code attribute.

CoA Request: Disable Host Port

This command is carried in a standard CoA-Request message that has this new VSA:

Cisco:Avpair="subscriber:command=disable-host-port"

If the session cannot be located, the switch returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the session is located, the switch disables the hosting port and returns a CoA-ACK message.

If the switch fails before returning a CoA-ACK to the client, the process is repeated on the new active switch when the request is re-sent from the client. If the switch fails after returning a CoA-ACK message to the client but before the operation has completed, the operation is restarted on the new active switch.

Note

A Disconnect-Request failure following command re-sending could be the result of either a successful session termination before change-over (if the Disconnect-ACK was not sent) or a session termination by other means (for example, a link failure) that occurred after the original command was issued and before the standby switch became active.

CoA Request: Bounce-Port

This command is carried in a standard CoA-Request message that contains the following VSA:

Cisco:Avpair="subscriber:command=bounce-host-port"

Because this command is session-oriented, it must be accompanied by one or more of the session identification attributes. If the session cannot be located, the switch returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the session is located, the switch disables the hosting port for a period of 10 seconds, re-enables it (port-bounce), and returns a CoA-ACK.

If the switch fails before returning a CoA-ACK to the client, the process is repeated on the new active switch when the request is re-sent from the client. If the switch fails after returning a CoA-ACK message to the client but before the operation has completed, the operation is re-started on the new active switch.

Stacking Guidelines for Session Termination

No special handling is required for CoA Disconnect-Request messages in a switch stack.

Stacking Guidelines for CoA-Request Bounce-Port

Because the bounce-port command is targeted at a session, not a port, if the session is not found, the command cannot be executed.

When the Auth Manager command handler on the stack master receives a valid bounce-port command, it checkpoints the following information before returning a CoA-ACK message:

the need for a port-bounce
the port-id (found in the local session context)

The switch initiates a port-bounce (disables the port for 10 seconds, then re-enables it).

If the port-bounce is successful, the signal that triggered the port-bounce is removed from the standby stack master.

If the stack master fails before the port-bounce completes, a port-bounce is initiated after stack master change-over based on the original command (which is subsequently removed).

If the stack master fails before sending a CoA-ACK message, the new stack master treats the re-sent command as a new command.

Stacking Guidelines for CoA-Request Disable-Port

Because the disable-port command is targeted at a session, not a port, if the session is not found, the command cannot be executed.

When the Auth Manager command handler on the stack master receives a valid disable-port command, it verifies this information before returning a CoA-ACK message:

the need for a port-disable
the port-id (found in the local session context)

The switch attempts to disable the port.

If the port-disable operation is successful, the signal that triggered the port-disable is removed from the standby stack master.

If the stack master fails before the port-disable operation completes, the port is disabled after stack master change-over based on the original command (which is subsequently removed).

If the stack master fails before sending a CoA-ACK message, the new stack master treats the re-sent command as a new command.

RADIUS Server Host

Switch-to-RADIUS-server communication involves several components:

Hostname or IP address
Authentication destination port
Accounting destination port
Key string
Timeout period
Retransmission value

You identify RADIUS security servers by their hostname or IP address, hostname and specific UDP port numbers, or their IP address and specific UDP port numbers. The combination of the IP address and the UDP port number creates a unique identifier, allowing different ports to be individually defined as RADIUS hosts providing a specific AAA service. This unique identifier enables RADIUS requests to be sent to multiple UDP ports on a server at the same IP address.

If two different host entries on the same RADIUS server are configured for the same service—for example, accounting—the second host entry configured acts as a fail-over backup to the first one. Using this example, if the first host entry fails to provide accounting services, the %RADIUS-4-RADIUS_DEAD message appears, and then the switch tries the second host entry configured on the same device for accounting services. (The RADIUS host entries are tried in the order that they are configured.)

A RADIUS server and the switch use a shared secret text string to encrypt passwords and exchange responses. To configure RADIUS to use the AAA security commands, you must specify the host running the RADIUS server daemon and a secret text (key) string that it shares with the switch.

The timeout, retransmission, and encryption key values can be configured globally for all RADIUS servers, on a per-server basis, or in some combination of global and per-server settings.

RADIUS Login Authentication

To configure AAA authentication, you define a named list of authentication methods and then apply that list to various ports. The method list defines the types of authentication to be performed and the sequence in which they are performed; it must be applied to a specific port before any of the defined authentication methods are performed. The only exception is the default method list. The default method list is automatically applied to all ports except those that have a named method list explicitly defined.

A method list describes the sequence and authentication methods to be queried to authenticate a user. You can designate one or more security protocols to be used for authentication, thus ensuring a backup system for authentication in case the initial method fails. The software uses the first method listed to authenticate users; if that method fails to respond, the software selects the next authentication method in the method list. This process continues until there is successful communication with a listed authentication method or until all defined methods are exhausted. If authentication fails at any point in this cycle—meaning that the security server or local username database responds by denying the user access—the authentication process stops, and no other authentication methods are attempted.

AAA Server Groups

You can configure the switch to use AAA server groups to group existing server hosts for authentication. You select a subset of the configured server hosts and use them for a particular service. The server group is used with a global server-host list, which lists the IP addresses of the selected server hosts.

Server groups also can include multiple host entries for the same server if each entry has a unique identifier (the combination of the IP address and UDP port number), allowing different ports to be individually defined as RADIUS hosts providing a specific AAA service. If you configure two different host entries on the same RADIUS server for the same service, (for example, accounting), the second configured host entry acts as a fail-over backup to the first one.

AAA Authorization

AAA authorization limits the services available to a user. When AAA authorization is enabled, the switch uses information retrieved from the user’s profile, which is in the local user database or on the security server, to configure the user’s session. The user is granted access to a requested service only if the information in the user profile allows it.

RADIUS Accounting

The AAA accounting feature tracks the services that users are using and the amount of network resources that they are consuming. When you enable AAA accounting, the switch reports user activity to the RADIUS security server in the form of accounting records. Each accounting record contains accounting attribute-value (AV) pairs and is stored on the security server. You can then analyze the data for network management, client billing, or auditing.

Vendor-Specific RADIUS Attributes

The Internet Engineering Task Force (IETF) draft standard specifies a method for communicating vendor-specific information between the switch and the RADIUS server by using the vendor-specific attribute (attribute 26). Vendor-specific attributes (VSAs) allow vendors to support their own extended attributes not suitable for general use. The Cisco RADIUS implementation supports one vendor-specific option by using the format recommended in the specification. Cisco’s vendor-ID is 9, and the supported option has vendor-type 1, which is named cisco-avpair. The value is a string with this format:


protocol : attribute sep value *

Protocol is a value of the Cisco protocol attribute for a particular type of authorization. Attribute and value are an appropriate attributevalue (AV) pair defined in the Cisco TACACS+ specification, and sep is = for mandatory attributes and is * for optional attributes. The full set of features available for TACACS+ authorization can then be used for RADIUS.

Other vendors have their own unique vendor-IDs, options, and associated VSAs. For more information about vendor-IDs and VSAs, see RFC 2138, “Remote Authentication Dial-In User Service (RADIUS).”

For a complete list of RADIUS attributes or more information about vendor-specific attribute 26, see the “RADIUS Attributes” appendix in the Cisco IOS Security Configuration Guide.

Vendor-Proprietary RADIUS Server Communication

Although an IETF draft standard for RADIUS specifies a method for communicating vendor-proprietary information between the switch and the RADIUS server, some vendors have extended the RADIUS attribute set in a unique way. Cisco IOS software supports a subset of vendor-proprietary RADIUS attributes.

As mentioned earlier, to configure RADIUS (whether vendor-proprietary or IETF draft-compliant), you must specify the host running the RADIUS server daemon and the secret text string it shares with the switch. You specify the RADIUS host and secret text string by using the radius-server global configuration commands.

Default RADIUS Configuration

RADIUS and AAA are disabled by default.

To prevent a lapse in security, you cannot configure RADIUS through a network management application. When enabled, RADIUS can authenticate users accessing the switch through the CLI.

Identifying the RADIUS Server Host

To apply these settings globally to all RADIUS servers communicating with the Switch, use the three unique global configuration commands: radius-server timeout , radius-server retransmit , and radius-server key . To apply these values on a specific RADIUS server, use the radius-server host global configuration command.

You can configure the Switch to use AAA server groups to group existing server hosts for authentication. For more information, see Related Topics below.

You also need to configure some settings on the RADIUS server. These settings include the IP address of the Switch and the key string to be shared by both the server and the Switch. For more information, see the RADIUS server documentation.

Follow these steps to configure per-server RADIUS server communication.

Before you begin

If you configure both global and per-server functions (timeout, retransmission, and key commands) on the switch, the per-server timer, retransmission, and key value commands override global timer, retransmission, and key value commands. For information on configuring these settings on all RADIUS servers, see Related Topics below.

SUMMARY STEPS

enable
configure terminal
radius-server host {hostname | ip-address} [auth-port port-number] [acct-port port-number] [timeout seconds] [retransmit retries] [key string]
end
show running-config
copy running-config startup-config

DETAILED STEPS

Command or Action Purpose

Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters the global configuration mode.

Step 3

radius-server host {hostname | ip-address} [auth-port port-number] [acct-port port-number] [timeout seconds] [retransmit retries] [key string]

Example:


Switch(config)# radius-server host 172.29.36.49 auth-port 1612 key rad1

Specifies the IP address or hostname of the remote RADIUS server host.

(Optional) For auth-port port-number , specify the UDP destination port for authentication requests.
(Optional) For acct-port port-number , specify the UDP destination port for accounting requests.
(Optional) For timeout seconds , specify the time interval that the Switch waits for the RADIUS server to reply before resending. The range is 1 to 1000. This setting overrides the radius-server timeout global configuration command setting. If no timeout is set with the radius-server host command, the setting of the radius-server timeout command is used.
(Optional) For retransmit retries , specify the number of times a RADIUS request is resent to a server if that server is not responding or responding slowly. The range is 1 to 1000. If no retransmit value is set with the radius-server host command, the setting of the radius-server retransmit global configuration command is used.
(Optional) For key string , specify the authentication and encryption key used between the Switch and the RADIUS daemon running on the RADIUS server.

Note

The key is a text string that must match the encryption key used on the RADIUS server. Always configure the key as the last item in the radius-server host command. Leading spaces are ignored, but spaces within and at the end of the key are used. If you use spaces in your key, do not enclose the key in quotation marks unless the quotation marks are part of the key.

To configure the Switch to recognize more than one host entry associated with a single IP address, enter this command as many times as necessary, making sure that each UDP port number is different. The Switch software searches for hosts in the order in which you specify them. Set the timeout, retransmit, and encryption key values to use with the specific RADIUS host.

Step 4

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 5

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 6

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring RADIUS Login Authentication

Follow these steps to configure RADIUS login authentication:

Before you begin

To secure the switch for HTTP access by using AAA methods, you must configure the switch with the ip http authentication aaa global configuration command. Configuring AAA authentication does not secure the switch for HTTP access by using AAA methods.

SUMMARY STEPS

enable
configure terminal
aaa new-model
aaa authentication login {default | list-name} method1 [method2...]
line [console | tty | vty ] line-number [ending-line-number]
login authentication {default | list-name}
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	aaa new-model Example: `Switch(config)# aaa new-model`	Enables AAA.
Step 4	aaa authentication login {default \| `list-name`} `method1` [`method2...`] Example: `Switch(config)# aaa authentication login default local`	Creates a login authentication method list. To create a default list that is used when a named list is not specified in the login authentication command, use the default keyword followed by the methods that are to be used in default situations. The default method list is automatically applied to all ports. For `list-name` , specify a character string to name the list you are creating. For `method1...` , specify the actual method the authentication algorithm tries. The additional methods of authentication are used only if the previous method returns an error, not if it fails. Select one of these methods: `enable` —Use the enable password for authentication. Before you can use this authentication method, you must define an enable password by using the enable `password` global configuration command. `group radius` —Use RADIUS authentication. Before you can use this authentication method, you must configure the RADIUS server. `line` —Use the line password for authentication. Before you can use this authentication method, you must define a line password. Use the password `password` line configuration command. `local` —Use the local username database for authentication. You must enter username information in the database. Use the username `name` password global configuration command. `local-case` —Use a case-sensitive local username database for authentication. You must enter username information in the database by using the username `password` global configuration command. `none` —Do not use any authentication for login.
Step 5	line [console \| tty \| vty ] `line-number` [`ending-line-number`] Example: `Switch(config)# line 1 4`	Enters line configuration mode, and configure the lines to which you want to apply the authentication list.
Step 6	login authentication {default \| `list-name`} Example: `Switch(config)# login authentication default`	Applies the authentication list to a line or set of lines. If you specify default , use the default list created with the aaa authentication login command. For `list-name` , specify the list created with the aaa authentication login command.
Step 7	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 8	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 9	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Defining AAA Server Groups

You use the server group server configuration command to associate a particular server with a defined group server. You can either identify the server by its IP address or identify multiple host instances or entries by using the optional auth-port and acct-port keywords.

Follow these steps to define AAA server groups:

SUMMARY STEPS

enable
configure terminal
radius-server host {hostname | ip-address} [auth-port port-number] [acct-port port-number] [timeout seconds] [retransmit retries] [key string]
aaa new-model
aaa group server radius group-name
server ip-address
end
show running-config
copy running-config startup-config

DETAILED STEPS

Command or Action Purpose

Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters the global configuration mode.

Step 3

radius-server host {hostname | ip-address} [auth-port port-number] [acct-port port-number] [timeout seconds] [retransmit retries] [key string]

Example:


Switch(config)# radius-server host 172.29.36.49 auth-port 1612 key rad1

Specifies the IP address or hostname of the remote RADIUS server host.

(Optional) For auth-port port-number , specify the UDP destination port for authentication requests.
(Optional) For acct-port port-number , specify the UDP destination port for accounting requests.
(Optional) For timeout seconds , specify the time interval that the switch waits for the RADIUS server to reply before resending. The range is 1 to 1000. This setting overrides the radius-server timeout global configuration command setting. If no timeout is set with the radius-server host command, the setting of the radius-server timeout command is used.
(Optional) For retransmit retries , specify the number of times a RADIUS request is resent to a server if that server is not responding or responding slowly. The range is 1 to 1000. If no retransmit value is set with the radius-server host command, the setting of the radius-server retransmit global configuration command is used.
(Optional) For key string , specify the authentication and encryption key used between the switch and the RADIUS daemon running on the RADIUS server.

Note

The key is a text string that must match the encryption key used on the RADIUS server. Always configure the key as the last item in the radius-server host command. Leading spaces are ignored, but spaces within and at the end of the key are used. If you use spaces in your key, do not enclose the key in quotation marks unless the quotation marks are part of the key.

To configure the switch to recognize more than one host entry associated with a single IP address, enter this command as many times as necessary, making sure that each UDP port number is different. The switch software searches for hosts in the order in which you specify them. Set the timeout, retransmit, and encryption key values to use with the specific RADIUS host.

Step 4

aaa new-model

Example:


Switch(config)# aaa new-model

Enables AAA.

Step 5

aaa group server radius group-name

Example:


Switch(config)# aaa group server radius group1

Defines the AAA server-group with a group name.

This command puts the switch in a server group configuration mode.

Step 6

server ip-address

Example:


Switch(config-sg-radius)# server 172.20.0.1 auth-port 1000 acct-port 1001

Associates a particular RADIUS server with the defined server group. Repeat this step for each RADIUS server in the AAA server group.

Each server in the group must be previously defined in Step 2.

Step 7

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 8

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 9

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring RADIUS Authorization for User Privileged Access and Network Services

Note

Authorization is bypassed for authenticated users who log in through the CLI even if authorization has been configured.

Follow these steps to configure RADIUS authorization for user priviledged access and network services:

SUMMARY STEPS

enable
configure terminal
aaa authorization network radius
aaa authorization exec radius
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	aaa authorization network radius Example: `Switch(config)# aaa authorization network radius`	Configures the switch for user RADIUS authorization for all network-related service requests.
Step 4	aaa authorization exec radius Example: `Switch(config)# aaa authorization exec radius`	Configures the switch for user RADIUS authorization if the user has privileged EXEC access. The exec keyword might return user profile information (such as autocommand information).
Step 5	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 6	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 7	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

What to do next

You can use the aaa authorization global configuration command with the radius keyword to set parameters that restrict a user’s network access to privileged EXEC mode.

The aaa authorization exec radius local command sets these authorization parameters:

Use RADIUS for privileged EXEC access authorization if authentication was performed by using RADIUS.
Use the local database if authentication was not performed by using RADIUS.

Starting RADIUS Accounting

Follow these steps to start RADIUS accounting:

SUMMARY STEPS

enable
configure terminal
aaa accounting network start-stop radius
aaa accounting exec start-stop radius
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	aaa accounting network start-stop radius Example: `Switch(config)# aaa accounting network start-stop radius`	Enables RADIUS accounting for all network-related service requests.
Step 4	aaa accounting exec start-stop radius Example: `Switch(config)# aaa accounting exec start-stop radius`	Enables RADIUS accounting to send a start-record accounting notice at the beginning of a privileged EXEC process and a stop-record at the end.
Step 5	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 6	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 7	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

What to do next

To establishing a session with a router if the AAA server is unreachable, use the aaa accounting system guarantee-first command. This command guarantees system accounting as the first record, which is the default condition. In some situations, users might be prevented from starting a session on the console or terminal connection until after the system reloads, which can take more than 3 minutes.

To establish a console or Telnet session with the router if the AAA server is unreachable when the router reloads, use the no aaa accounting system guarantee-first command.

Configuring Settings for All RADIUS Servers

Beginning in privileged EXEC mode, follow these steps to configure settings for all RADIUS servers:

SUMMARY STEPS

configure terminal
radius-server key string
radius-server retransmit retries
radius-server timeout seconds
radius-server deadtime minutes
end
show running-config
copy running-config startup-config

DETAILED STEPS

Command or Action Purpose

Step 1

configure terminal

Example:


Switch# configure terminal

Enters the global configuration mode.

Step 2

radius-server key string

Example:


Switch(config)# radius-server key your_server_key

Specifies the shared secret text string used between the switch and all RADIUS servers.

Note

The key is a text string that must match the encryption key used on the RADIUS server. Leading spaces are ignored, but spaces within and at the end of the key are used. If you use spaces in your key, do not enclose the key in quotation marks unless the quotation marks are part of the key.

Step 3

radius-server retransmit retries

Example:


Switch(config)# radius-server retransmit 5

Specifies the number of times the switch sends each RADIUS request to the server before giving up. The default is 3; the range 1 to 1000.

Step 4

radius-server timeout seconds

Example:


Switch(config)# radius-server timeout 3

Specifies the number of seconds a switch waits for a reply to a RADIUS request before resending the request. The default is 5 seconds; the range is 1 to 1000.

Step 5

radius-server deadtime minutes

Example:


Switch(config)# radius-server deadtime 0

When a RADIUS server is not responding to authentication requests, this command specifies a time to stop the request on that server. This avoids the wait for the request to timeout before trying the next configured server. The default is 0; the range is 1 to 1440 minutes.

Step 6

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 7

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 8

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring the Switch to Use Vendor-Specific RADIUS Attributes

Follow these steps to configure the switch to use vendor-specific RADIUS attributes:

SUMMARY STEPS

enable
configure terminal
radius-server vsa send [accounting | authentication ]
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	radius-server vsa send [accounting \| authentication ] Example: `Switch(config)# radius-server vsa send`	Enables the switch to recognize and use VSAs as defined by RADIUS IETF attribute 26. (Optional) Use the accounting keyword to limit the set of recognized vendor-specific attributes to only accounting attributes. (Optional) Use the authentication keyword to limit the set of recognized vendor-specific attributes to only authentication attributes. If you enter this command without keywords, both accounting and authentication vendor-specific attributes are used.
Step 4	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 5	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 6	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Configuring the Switch for Vendor-Proprietary RADIUS Server Communication

Follow these steps to configure the switch to use vendor-proprietary RADIUS server communication:

SUMMARY STEPS

enable
configure terminal
radius-server host {hostname | ip-address} non-standard
radius-server key string
end
show running-config
copy running-config startup-config

DETAILED STEPS

Command or Action Purpose

Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters the global configuration mode.

Step 3

radius-server host {hostname | ip-address} non-standard

Example:


Switch(config)# radius-server host 172.20.30.15 nonstandard

Specifies the IP address or hostname of the remote RADIUS server host and identifies that it is using a vendor-proprietary implementation of RADIUS.

Step 4

radius-server key string

Example:


Switch(config)# radius-server key rad124

Specifies the shared secret text string used between the switch and the vendor-proprietary RADIUS server. The switch and the RADIUS server use this text string to encrypt passwords and exchange responses.

Note

The key is a text string that must match the encryption key used on the RADIUS server. Leading spaces are ignored, but spaces within and at the end of the key are used. If you use spaces in your key, do not enclose the key in quotation marks unless the quotation marks are part of the key.

Step 5

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

What to do next

This feature allows access and authentication requests to be evenly across all RADIUS servers in a server group. For more information, see the “RADIUS Server Load Balancing” chapter of the Cisco IOS Security Configuration Guide, Release 12.4.

Configuring CoA on the Switch

Follow these steps to configure CoA on a switch. This procedure is required.

SUMMARY STEPS

enable
configure terminal
aaa new-model
aaa server radius dynamic-author
client {ip-address | name} [vrf vrfname] [server-key string]
server-key [0 | 7 ] string
port port-number
auth-type {any | all | session-key }
ignore session-key
ignore server-key
authentication command bounce-port ignore
authentication command disable-port ignore
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	aaa new-model Example: `Switch(config)# aaa new-model`	Enables AAA.
Step 4	aaa server radius dynamic-author Example: `Switch(config)# aaa server radius dynamic-author`	Configures the switch as an authentication, authorization, and accounting (AAA) server to facilitate interaction with an external policy server.
Step 5	client {`ip-address` \| `name`} [vrf `vrfname`] [server-key `string`]	Enters dynamic authorization local server configuration mode and specifies a RADIUS client from which a device will accept CoA and disconnect requests.
Step 6	server-key [0 \| 7 ] `string` Example: `Switch(config-sg-radius)# server-key your_server_key`	Configures the RADIUS key to be shared between a device and RADIUS clients.
Step 7	port `port-number` Example: `Switch(config-sg-radius)# port 25`	Specifies the port on which a device listens for RADIUS requests from configured RADIUS clients.
Step 8	auth-type {any \| all \| session-key } Example: `Switch(config-sg-radius)# auth-type any`	Specifies the type of authorization the switch uses for RADIUS clients. The client must match all the configured attributes for authorization.
Step 9	ignore session-key	(Optional) Configures the switch to ignore the session-key. For more information about the ignore command, see the Cisco IOS Intelligent Services Gateway Command Reference on Cisco.com.
Step 10	ignore server-key Example: `Switch(config-sg-radius)# ignore server-key`	(Optional) Configures the switch to ignore the server-key. For more information about the ignore command, see the Cisco IOS Intelligent Services Gateway Command Reference on Cisco.com.
Step 11	authentication command bounce-port ignore Example: `Switch(config-sg-radius)# authentication command bounce-port ignore`	(Optional) Configures the switch to ignore a CoA request to temporarily disable the port hosting a session. The purpose of temporarily disabling the port is to trigger a DHCP renegotiation from the host when a VLAN change occurs and there is no supplicant on the endpoint to detect the change.
Step 12	authentication command disable-port ignore Example: `Switch(config-sg-radius)# authentication command disable-port ignore`	(Optional) Configures the switch to ignore a nonstandard command requesting that the port hosting a session be administratively shut down. Shutting down the port results in termination of the session. Use standard CLI or SNMP commands to re-enable the port.
Step 13	end Example: `Switch(config-sg-radius)# end`	Returns to privileged EXEC mode.
Step 14	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 15	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Monitoring CoA Functionality

Table 7. Privileged EXEC show Commands
Command	Purpose
show aaa attributes protocol radius	Displays AAA attributes of RADIUS commands.

Table 8. Global Troubleshooting Commands
Command	Purpose
debug radius	Displays information for troubleshooting RADIUS.
debug aaa coa	Displays information for troubleshooting CoA processing.
debug aaa pod	Displays information for troubleshooting POD packets.
debug aaa subsys	Displays information for troubleshooting POD packets.
debug cmdhd [detail \| error \| events ]	Displays information for troubleshooting command headers.

For detailed information about the fields in these displays, see the command reference for this release.

Configuration Examples for Controlling Switch Access with RADIUS

Examples: Identifying the RADIUS Server Host

This example shows how to configure one RADIUS server to be used for authentication and another to be used for accounting:


Switch(config)# radius-server host 172.29.36.49 auth-port 1612 key rad1
Switch(config)# radius-server host 172.20.36.50 acct-port 1618 key rad2

This example shows how to configure host1 as the RADIUS server and to use the default ports for both authentication and accounting:


Switch(config)# radius-server host host1

Example: Using Two Different RADIUS Group Servers

In this example, the switch is configured to recognize two different RADIUS group servers (group1 and group2). Group1 has two different host entries on the same RADIUS server configured for the same services. The second host entry acts as a fail-over backup to the first entry.


Switch(config)# radius-server host 172.20.0.1 auth-port 1000 acct-port 1001
Switch(config)# radius-server host 172.10.0.1 auth-port 1645 acct-port 1646
Switch(config)# aaa new-model
Switch(config)# aaa group server radius group1
Switch(config-sg-radius)# server 172.20.0.1 auth-port 1000 acct-port 1001
Switch(config-sg-radius)# exit
Switch(config)# aaa group server radius group2
Switch(config-sg-radius)# server 172.20.0.1 auth-port 2000 acct-port 2001
Switch(config-sg-radius)# exit

Examples: Configuring the Switch to Use Vendor-Specific RADIUS Attributes

For example, this AV pair activates Cisco’s multiple named ip address pools feature during IP authorization (during PPP IPCP address assignment):


cisco-avpair= ”ip:addr-pool=first“

This example shows how to provide a user logging in from a switch with immediate access to privileged EXEC commands:


cisco-avpair= ”shell:priv-lvl=15“

This example shows how to specify an authorized VLAN in the RADIUS server database:


cisco-avpair= ”tunnel-type(#64)=VLAN(13)”
cisco-avpair= ”tunnel-medium-type(#65)=802 media(6)”
cisco-avpair= ”tunnel-private-group-id(#81)=vlanid”

This example shows how to apply an input ACL in ASCII format to an interface for the duration of this connection:


cisco-avpair= “ip:inacl#1=deny ip 10.10.10.10 0.0.255.255 20.20.20.20 255.255.0.0”
cisco-avpair= “ip:inacl#2=deny ip 10.10.10.10 0.0.255.255 any”
cisco-avpair= “mac:inacl#3=deny any any decnet-iv”

This example shows how to apply an output ACL in ASCII format to an interface for the duration of this connection:


cisco-avpair= “ip:outacl#2=deny ip 10.10.10.10 0.0.255.255 any”

Example: Configuring the Switch for Vendor-Proprietary RADIUS Server Communication

This example shows how to specify a vendor-proprietary RADIUS host and to use a secret key of rad124 between the switch and the server:


Switch(config)# radius-server host 172.20.30.15 nonstandard
Switch(config)# radius-server key rad124

Unsupported Commands: RADIUS

Unsupported Global Configuration Commands

aaa nas port extended
aaa authentication [feature] default enable
aaa authentication [feature] default line
radius-server attribute nas-port
radius-server configure
radius-server extended-portnames

Additional References

Related Topic	Document Title
“RADIUS Over IPv6” section of the “Implementing ADSL for IPv6” chapter	Cisco IOS XE IPv6 Configuration Guide, Release 2
“Configuring the NAS” section in the “Implementing ADSL for IPv6” chapter	Cisco IOS XE IPv6 Configuration Guide, Release 2
IPv6 commands	Cisco IOS IPv6 Command Reference
Commands used in the section	Cisco IOS Security Command Reference, Release 12.4

Standards and RFCs


Standard/RFC	Title
RFC 5176	RADIUS Change of Authorization (CoA) extensions

Error Message Decoder


Description	Link
To help you research and resolve system error messages in this release, use the Error Message Decoder tool.	https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi

MIBs


MIB	MIBs Link
All supported MIBs for this release.	To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

Technical Assistance


Description	Link
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.	http://www.cisco.com/support

Feature Information for RADIUS


Release	Feature Information
	This feature was introduced.
Cisco IOS 12.2(52)SE	Introduced support for per-session CoA requests.
Cisco IOS 12.2(52)SE	Introduced support for the following CoA Request commands: Reauthenticate host Terminate session Bounce host port Disable host port

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Controlling Switch Access with Kerberos

The following are the prerequisites for controlling switch access with Kerberos.

So that remote users can authenticate to network services, you must configure the hosts and the KDC in the Kerberos realm to communicate and mutually authenticate users and network services. To do this, you must identify them to each other. You add entries for the hosts to the Kerberos database on the KDC and add KEYTAB files generated by the KDC to all hosts in the Kerberos realm. You also create entries for the users in the KDC database.
A Kerberos server can be a switch that is configured as a network security server and that can authenticate users by using the Kerberos protocol.

When you add or create entries for the hosts and users, follow these guidelines:

The Kerberos principal name must be in all lowercase characters.
The Kerberos instance name must be in all lowercase characters.
The Kerberos realm name must be in all uppercase characters.

Restrictions for Controlling Switch Access with Kerberos

The following lists any restrictions for controlling switch access with Kerberos.

Kerberos and Switch Access

This section describes how to enable and configure the Kerberos security system, which authenticates requests for network resources by using a trusted third party.

Note

In the Kerberos configuration examples and in the Cisco IOS Security Command Reference, Release 12.4, the trusted third party can be a Catalyst 3750-E or 3560-E switch that supports Kerberos, that is configured as a network security server, and that can authenticate users by using the Kerberos protocol.

Kerberos Overview

Kerberos is a secret-key network authentication protocol, which was developed at the Massachusetts Institute of Technology (MIT). It uses the Data Encryption Standard (DES) cryptographic algorithm for encryption and authentication and authenticates requests for network resources. Kerberos uses the concept of a trusted third party to perform secure verification of users and services. This trusted third party is called the key distribution center (KDC).

Kerberos verifies that users are who they claim to be and the network services that they use are what the services claim to be. To do this, a KDC or trusted Kerberos server issues tickets to users. These tickets, which have a limited life span, are stored in user credential caches. The Kerberos server uses the tickets instead of user names and passwords to authenticate users and network services.

Note

A Kerberos server can be a Catalyst 3750-E or 3560-E Catalyst 3750-X or 3560-X switch that is configured as a network security server and that can authenticate users by using the Kerberos protocol.

The Kerberos credential scheme uses a process called single logon. This process authenticates a user once and then allows secure authentication (without encrypting another password) wherever that user credential is accepted.

This software release supports Kerberos 5, which allows organizations that are already using Kerberos 5 to use the same Kerberos authentication database on the KDC that they are already using on their other network hosts (such as UNIX servers and PCs).

Kerberos supports these network services:

Telnet
rlogin
rsh

This table lists the common Kerberos-related terms and definitions.

Table 9. Kerberos Terms

Term

Definition

Authentication

A process by which a user or service identifies itself to another service. For example, a client can authenticate to a switch or a switch can authenticate to another switch.

Authorization

A means by which the switch identifies what privileges the user has in a network or on the switch and what actions the user can perform.

Credential

A general term that refers to authentication tickets, such as TGTs² and service credentials. Kerberos credentials verify the identity of a user or service. If a network service decides to trust the Kerberos server that issued a ticket, it can be used in place of re-entering a username and password. Credentials have a default life span of eight hours.

Instance

An authorization level label for Kerberos principals. Most Kerberos principals are of the form user@REALM (for example, smith@EXAMPLE.COM). A Kerberos principal with a Kerberos instance has the form user/instance@REALM (for example, smith/admin@EXAMPLE.COM). The Kerberos instance can be used to specify the authorization level for the user if authentication is successful. The server of each network service might implement and enforce the authorization mappings of Kerberos instances but is not required to do so.

Note

The Kerberos principal and instance names must be in all lowercase characters.

Note

The Kerberos realm name must be in all uppercase characters.

KDC³

Key distribution center that consists of a Kerberos server and database program that is running on a network host.

Kerberized

A term that describes applications and services that have been modified to support the Kerberos credential infrastructure.

Kerberos realm

A domain consisting of users, hosts, and network services that are registered to a Kerberos server. The Kerberos server is trusted to verify the identity of a user or network service to another user or network service.

Note

The Kerberos realm name must be in all uppercase characters.

Kerberos server

A daemon that is running on a network host. Users and network services register their identity with the Kerberos server. Network services query the Kerberos server to authenticate to other network services.

KEYTAB⁴

A password that a network service shares with the KDC. In Kerberos 5 and later Kerberos versions, the network service authenticates an encrypted service credential by using the KEYTAB to decrypt it. In Kerberos versions earlier than Kerberos 5, KEYTAB is referred to as SRVTAB⁵.

Principal

Also known as a Kerberos identity, this is who you are or what a service is according to the Kerberos server.

Note

The Kerberos principal name must be in all lowercase characters.

Service credential

A credential for a network service. When issued from the KDC, this credential is encrypted with the password shared by the network service and the KDC. The password is also shared with the user TGT.

SRVTAB

A password that a network service shares with the KDC. In Kerberos 5 or later Kerberos versions, SRVTAB is referred to as KEYTAB.

TGT

Ticket granting ticket that is a credential that the KDC issues to authenticated users. When users receive a TGT, they can authenticate to network services within the Kerberos realm represented by the KDC.

² ticket granting ticket

³ key distribution center

⁴ key table

⁵ server table

Kerberos Operation

A Kerberos server can be a Catalyst 3750-E or 3560-E Catalyst 3750-X or 3560-X switch that is configured as a network security server and that can authenticate remote users by using the Kerberos protocol. Although you can customize Kerberos in a number of ways, remote users attempting to access network services must pass through three layers of security before they can access network services.

To authenticate to network services by using a Catalyst 3750-E or 3560-E Catalyst 3750-X or 3560-X switch as a Kerberos server, remote users must follow these steps:

Authenticating to a Boundary Switch
Obtaining a TGT from a KDC
Authenticating to Network Services

Authenticating to a Boundary Switch

This section describes the first layer of security through which a remote user must pass. The user must first authenticate to the boundary switch. This process then occurs:

The user opens an un-Kerberized Telnet connection to the boundary switch.
The switch prompts the user for a username and password.
The switch requests a TGT from the KDC for this user.
The KDC sends an encrypted TGT that includes the user identity to the switch.
The switch attempts to decrypt the TGT by using the password that the user entered.
- If the decryption is successful, the user is authenticated to the switch.
- If the decryption is not successful, the user repeats Step 2 either by re-entering the username and password (noting if Caps Lock or Num Lock is on or off) or by entering a different username and password.

A remote user who initiates a un-Kerberized Telnet session and authenticates to a boundary switch is inside the firewall, but the user must still authenticate directly to the KDC before getting access to the network services. The user must authenticate to the KDC because the TGT that the KDC issues is stored on the switch and cannot be used for additional authentication until the user logs on to the switch.

Obtaining a TGT from a KDC

This section describes the second layer of security through which a remote user must pass. The user must now authenticate to a KDC and obtain a TGT from the KDC to access network services.

For instructions about how to authenticate to a KDC, see the “Obtaining a TGT from a KDC” section in the “Security Server Protocols” chapter of the Cisco IOS Security Configuration Guide, Release 12.4.

Authenticating to Network Services

This section describes the third layer of security through which a remote user must pass. The user with a TGT must now authenticate to the network services in a Kerberos realm.

For instructions about how to authenticate to a network service, see the “Authenticating to Network Services” section in the “Security Server Protocols” chapter of the Cisco IOS Security Configuration Guide, Release 12.4.

How to Configure Kerberos

To set up a Kerberos-authenticated server-client system, follow these steps:

Configure the KDC by using Kerberos commands.
Configure the switch to use the Kerberos protocol.

For instructions, see the “Kerberos Configuration Task List” section in the “Security Server Protocols” chapter of the Cisco IOS Security Configuration Guide, Release 12.4.

Monitoring the Kerberos Configuration

To display the Kerberos configuration, use the show running-config privileged EXEC command.

Additional References

Error Message Decoder


Description	Link
To help you research and resolve system error messages in this release, use the Error Message Decoder tool.	https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi

MIBs


MIB	MIBs Link
All supported MIBs for this release.	To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

Technical Assistance


Description	Link
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.	http://www.cisco.com/support

Feature Information for Kerberos


Release	Feature Information
	This feature was introduced.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Configuring the Switch for Local Authentication and Authorization

You can configure AAA to operate without a server by setting the switch to implement AAA in local mode. The switch then handles authentication and authorization. No accounting is available in this configuration.

Note

To secure the switch for HTTP access by using AAA methods, you must configure the switch with the ip http authentication aaa global configuration command. Configuring AAA authentication does not secure the switch for HTTP access by using AAA methods.

Follow these steps to configure AAA to operate without a server by setting the switch to implement AAA in local mode:

SUMMARY STEPS

enable
configure terminal
aaa new-model
aaa authentication login default local
aaa authorization exec local
aaa authorization network local
username name [privilege level] {password encryption-type password}
end
show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	aaa new-model Example: `Switch(config)# aaa new-model`	Enables AAA.
Step 4	aaa authentication login default local Example: `Switch(config)# aaa authentication login default local`	Sets the login authentication to use the local username database. The default keyword applies the local user database authentication to all ports.
Step 5	aaa authorization exec local Example: `Switch(config)# aaa authorization exec local`	Configures user AAA authorization, check the local database, and allow the user to run an EXEC shell.
Step 6	aaa authorization network local Example: `Switch(config)# aaa authorization network local`	Configures user AAA authorization for all network-related service requests.
Step 7	username `name` [privilege `level`] {password `encryption-type` `password`} Example: `Switch(config)# username your_user_name privilege 1 password 7 secret567`	Enters the local database, and establishes a username-based authentication system. Repeat this command for each user. For `name` , specify the user ID as one word. Spaces and quotation marks are not allowed. (Optional) For `level` , specify the privilege level the user has after gaining access. The range is 0 to 15. Level 15 gives privileged EXEC mode access. Level 0 gives user EXEC mode access. For `encryption-type` , enter 0 to specify that an unencrypted password follows. Enter 7 to specify that a hidden password follows. For `password` , specify the password the user must enter to gain access to the switch. The password must be from 1 to 25 characters, can contain embedded spaces, and must be the last option specified in the username command.
Step 8	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 9	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 10	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Monitoring Local Authentication and Authorization

To display Local Authentication and Authorization configuration, use the show running-config privileged EXEC command.

Additional References

Error Message Decoder


Description	Link
To help you research and resolve system error messages in this release, use the Error Message Decoder tool.	https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi

MIBs


MIB	MIBs Link
All supported MIBs for this release.	To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

Technical Assistance


Description	Link
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.	http://www.cisco.com/support

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Configuring the Switch for Secure Shell (SSH) and Secure Copy Protocol (SCP)

The following are the prerequisites for configuring the switch for secure shell (SSH):

For SSH to work, the switch needs an RSA public/private key pair. This is the same with Secure Copy Protocol (SCP), which relies on SSH for its secure transport.
Before enabling SCP, you must correctly configure SSH, authentication, and authorization on the switch.
Because SCP relies on SSH for its secure transport, the router must have an Rivest, Shamir, and Adelman (RSA) key pair.
SCP relies on SSH for security.
SCP requires that authentication, authorization, and accounting (AAA) authorization be configured so the router can determine whether the user has the correct privilege level.
A user must have appropriate authorization to use SCP.
A user who has appropriate authorization can use SCP to copy any file in the Cisco IOS File System (IFS) to and from a switch by using the copy command. An authorized administrator can also do this from a workstation.

Restrictions for Configuring the Switch for SSH

The following are restrictions for configuring the Switch for secure shell.

The switch supports Rivest, Shamir, and Adelman (RSA) authentication.
SSH supports only the execution-shell application.
The SSH server and the SSH client are supported only on DES (56-bit) and 3DES (168-bit) data encryption software.
The Switch supports the Advanced Encryption Standard (AES) encryption algorithm with a 128-bit key, 192-bit key, or 256-bit key. However, symmetric cipher AES to encrypt the keys is not supported.
This software release does not support IP Security (IPSec).
When using SCP, you cannot enter the password into the copy command. You must enter the password when prompted.

SSH and Switch Access

Secure Shell (SSH) is a protocol that provides a secure, remote connection to a device. SSH provides more security for remote connections than Telnet does by providing strong encryption when a device is authenticated. This software release supports SSH Version 1 (SSHv1) and SSH Version 2 (SSHv2).

SSH functions the same in IPv6 as in IPv4. For IPv6, SSH supports IPv6 addresses and enables secure, encrypted connections with remote IPv6 nodes over an IPv6 transport.

SSH Servers, Integrated Clients, and Supported Versions

The SSH feature has an SSH server and an SSH integrated client, which are applications that run on the switch. You can use an SSH client to connect to a switch running the SSH server. The SSH server works with the SSH client supported in this release and with non-Cisco SSH clients. The SSH client also works with the SSH server supported in this release and with non-Cisco SSH servers.

The switch supports an SSHv1 or an SSHv2 server.

The switch supports an SSHv1 client.

SSH supports the Data Encryption Standard (DES) encryption algorithm, the Triple DES (3DES) encryption algorithm, and password-based user authentication.

SSH also supports these user authentication methods:

TACACS+
RADIUS
Local authentication and authorization

SSH Configuration Guidelines

Follow these guidelines when configuring the switch as an SSH server or SSH client:

An RSA key pair generated by a SSHv1 server can be used by an SSHv2 server, and the reverse.
If the SSH server is running on a stack master and the stack master fails, the new stack master uses the RSA key pair generated by the previous stack master.
If you get CLI error messages after entering the crypto key generate rsa global configuration command, an RSA key pair has not been generated. Reconfigure the hostname and domain, and then enter the crypto key generate rsa command. For more information, see Related Topics below.
When generating the RSA key pair, the message No host name specified might appear. If it does, you must configure a hostname by using the hostname global configuration command.
When generating the RSA key pair, the message No domain specified might appear. If it does, you must configure an IP domain name by using the ip domain-name global configuration command.
When configuring the local authentication and authorization authentication method, make sure that AAA is disabled on the console.

Secure Copy Protocol Overview

The Secure Copy Protocol (SCP) feature provides a secure and authenticated method for copying switch configurations or switch image files. SCP relies on Secure Shell (SSH), an application and a protocol that provides a secure replacement for the Berkeley r-tools.

For SSH to work, the switch needs an RSA public/private key pair. This is the same with SCP, which relies on SSH for its secure transport.

Because SSH also relies on AAA authentication, and SCP relies further on AAA authorization, correct configuration is necessary.

Before enabling SCP, you must correctly configure SSH, authentication, and authorization on the switch.
Because SCP relies on SSH for its secure transport, the router must have an Rivest, Shamir, and Adelman (RSA) key pair.

Note

When using SCP, you cannot enter the password into the copy command. You must enter the password when prompted.

Secure Copy Protocol

The Secure Copy Protocol (SCP) feature provides a secure and authenticated method for copying switch configurations or switch image files. The behavior of SCP is similar to that of remote copy (rcp), which comes from the Berkeley r-tools suite, except that SCP relies on SSH for security. SCP also requires that authentication, authorization, and accounting (AAA) authorization be configured so the switch can determine whether the user has the correct privilege level. To configure the Secure Copy feature, you should understand the SCP concepts.

Information about SSH

Secure Shell (SSH) is a protocol that provides a secure, remote connection to a device. SSH provides more security for remote connections than Telnet does by providing strong encryption when a device is authenticated. This software release supports SSH Version 1 (SSHv1) and SSH Version 2 (SSHv2).

Setting Up the Switch to Run SSH

Follow these steps to set up your Switch to run SSH:

Before you begin

Configure user authentication for local or remote access. This step is required. For more information, see Related Topics below.

SUMMARY STEPS

enable
configure terminal
hostname hostname
ip domain-name domain_name
crypto key generate rsa
end
Use one of the following ommands:

show ip ssh
show ssh

show running-config
copy running-config startup-config

DETAILED STEPS

Command or Action Purpose

Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters the global configuration mode.

Step 3

hostname hostname

Example:


Switch(config)# hostname your_hostname

Configures a hostname and IP domain name for your Switch.

Note

Follow this procedure only if you are configuring the Switch as an SSH server.

Step 4

ip domain-name domain_name

Example:


Switch(config)# ip domain-name your_domain

Configures a host domain for your Switch.

Step 5

crypto key generate rsa

Example:


Switch(config)# crypto key generate rsa

Enables the SSH server for local and remote authentication on the Switch and generates an RSA key pair. Generating an RSA key pair for the Switch automatically enables SSH.

We recommend that a minimum modulus size of 1024 bits.

When you generate RSA keys, you are prompted to enter a modulus length. A longer modulus length might be more secure, but it takes longer to generate and to use.

Note

Follow this procedure only if you are configuring the Switch as an SSH server.

Step 6

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 7

Use one of the following ommands:

show ip ssh
show ssh

Example:

Switch# show ip ssh

or

Switch# show ssh

Shows the version and configuration information for your SSH server.
Shows the status of the SSH server on the Switch.

Step 8

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 9

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring the SSH Server

Follow these steps to configure the SSH server:

Note

This procedure is only required if you are configuring the Switch as an SSH server.

SUMMARY STEPS

enable
configure terminal
ip ssh version [1 | 2 ]
ip ssh {timeout seconds | authentication-retries number}
Use one or both of the following:

line vty line_number [ending_line_number]
transport input ssh

end
Use one of the following:

show ip ssh
show ssh

show running-config
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	ip ssh version [1 \| 2 ] Example: `Switch(config)# ip ssh version 1`	(Optional) Configures the Switch to run SSH Version 1 or SSH Version 2. 1 —Configure the Switch to run SSH Version 1. 2 —Configure the Switch to run SSH Version 2. If you do not enter this command or do not specify a keyword, the SSH server selects the latest SSH version supported by the SSH client. For example, if the SSH client supports SSHv1 and SSHv2, the SSH server selects SSHv2.
Step 4	ip ssh {timeout `seconds` \| authentication-retries `number`} Example: `Switch(config)# ip ssh timeout 90 authentication-retries 2`	Configures the SSH control parameters: Specify the time-out value in seconds; the default is 120 seconds. The range is 0 to 120 seconds. This parameter applies to the SSH negotiation phase. After the connection is established, the Switch uses the default time-out values of the CLI-based sessions. By default, up to five simultaneous, encrypted SSH connections for multiple CLI-based sessions over the network are available (session 0 to session 4). After the execution shell starts, the CLI-based session time-out value returns to the default of 10 minutes. Specify the number of times that a client can re-authenticate to the server. The default is 3; the range is 0 to 5. Repeat this step when configuring both parameters.
Step 5	Use one or both of the following: line vty `line_number` `[ending_line_number]` transport input ssh Example: `Switch(config)# line vty 1 10` or `Switch(config-line)# transport input ssh`	(Optional) Configures the virtual terminal line settings. Enters line configuration mode to configure the virtual terminal line settings. For `line_number` and `ending_line_number` , specify a pair of lines. The range is 0 to 15. Specifies that the Switch prevent non-SSH Telnet connections. This limits the router to only SSH connections.
Step 6	end Example: `Switch(config-line)# end`	Returns to privileged EXEC mode.
Step 7	Use one of the following: show ip ssh show ssh Example: `Switch# show ip ssh` or `Switch# show ssh`	Shows the version and configuration information for your SSH server. Shows the status of the SSH server connections on the Switch.
Step 8	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 9	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Monitoring the SSH Configuration and Status

This table displays the SSH server configuration and status.

Table 10. Commands for Displaying the SSH Server Configuration and Status
Command	Purpose
show ip ssh	Shows the version and configuration information for the SSH server.
show ssh	Shows the status of the SSH server.

Additional References

Technical Assistance


Description	Link
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.	http://www.cisco.com/support

Feature Information for SSH


Release	Feature Information
	This feature was introduced.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

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Secure HTTP Servers and Clients Overview

On a secure HTTP connection, data to and from an HTTP server is encrypted before being sent over the Internet. HTTP with SSL encryption provides a secure connection to allow such functions as configuring a switch from a Web browser. Cisco's implementation of the secure HTTP server and secure HTTP client uses an implementation of SSL Version 3.0 with application-layer encryption. HTTP over SSL is abbreviated as HTTPS; the URL of a secure connection begins with https:// instead of http://.

Note

SSL evolved into Transport Layer Security (TLS) in 1999, but is still used in this particular context.

The primary role of the HTTP secure server (the switch) is to listen for HTTPS requests on a designated port (the default HTTPS port is 443) and pass the request to the HTTP 1.1 Web server. The HTTP 1.1 server processes requests and passes responses (pages) back to the HTTP secure server, which, in turn, responds to the original request.

The primary role of the HTTP secure client (the web browser) is to respond to Cisco IOS application requests for HTTPS User Agent services, perform HTTPS User Agent services for the application, and pass the response back to the application.

Certificate Authority Trustpoints

Certificate authorities (CAs) manage certificate requests and issue certificates to participating network devices. These services provide centralized security key and certificate management for the participating devices. Specific CA servers are referred to as trustpoints.

When a connection attempt is made, the HTTPS server provides a secure connection by issuing a certified X.509v3 certificate, obtained from a specified CA trustpoint, to the client. The client (usually a Web browser), in turn, has a public key that allows it to authenticate the certificate.

For secure HTTP connections, we highly recommend that you configure a CA trustpoint. If a CA trustpoint is not configured for the device running the HTTPS server, the server certifies itself and generates the needed RSA key pair. Because a self-certified (self-signed) certificate does not provide adequate security, the connecting client generates a notification that the certificate is self-certified, and the user has the opportunity to accept or reject the connection. This option is useful for internal network topologies (such as testing).

If you do not configure a CA trustpoint, when you enable a secure HTTP connection, either a temporary or a persistent self-signed certificate for the secure HTTP server (or client) is automatically generated.

If the switch is not configured with a hostname and a domain name, a temporary self-signed certificate is generated. If the switch reboots, any temporary self-signed certificate is lost, and a new temporary new self-signed certificate is assigned.
If the switch has been configured with a host and domain name, a persistent self-signed certificate is generated. This certificate remains active if you reboot the switch or if you disable the secure HTTP server so that it will be there the next time you re-enable a secure HTTP connection.

Note

The certificate authorities and trustpoints must be configured on each device individually. Copying them from other devices makes them invalid on the switch.

If a self-signed certificate has been generated, this information is included in the output of the show running-config privileged EXEC command. This is a partial sample output from that command displaying a self-signed certificate.


Switch# show running-config
Building configuration...

<output truncated>

crypto pki trustpoint TP-self-signed-3080755072
 enrollment selfsigned
 subject-name cn=IOS-Self-Signed-Certificate-3080755072
 revocation-check none
 rsakeypair TP-self-signed-3080755072
!
!
crypto ca certificate chain TP-self-signed-3080755072
 certificate self-signed 01
  3082029F 30820208 A0030201 02020101 300D0609 2A864886 F70D0101 04050030
  59312F30 2D060355 04031326 494F532D 53656C66 2D536967 6E65642D 43657274
  69666963 6174652D 33303830 37353530 37323126 30240609 2A864886 F70D0109
  02161743 45322D33 3535302D 31332E73 756D6D30 342D3335 3530301E 170D3933
  30333031 30303030 35395A17 0D323030 31303130 30303030 305A3059 312F302D

<output truncated>

You can remove this self-signed certificate by disabling the secure HTTP server and entering the no crypto pki trustpoint TP-self-signed-30890755072 global configuration command. If you later re-enable a secure HTTP server, a new self-signed certificate is generated.

Note

The values that follow TP self-signed depend on the serial number of the device.

You can use an optional command (ip http secure-client-auth ) to allow the HTTPS server to request an X.509v3 certificate from the client. Authenticating the client provides more security than server authentication by itself.

For additional information on Certificate Authorities, see the “Configuring Certification Authority Interoperability” chapter in the Cisco IOS Security Configuration Guide, Release 12.4.

CipherSuites

A CipherSuite specifies the encryption algorithm and the digest algorithm to use on a SSL connection. When connecting to the HTTPS server, the client Web browser offers a list of supported CipherSuites, and the client and server negotiate the best encryption algorithm to use from those on the list that are supported by both. For example, Netscape Communicator 4.76 supports U.S. security with RSA Public Key Cryptography, MD2, MD5, RC2-CBC, RC4, DES-CBC, and DES-EDE3-CBC.

For the best possible encryption, you should use a client browser that supports 128-bit encryption, such as Microsoft Internet Explorer Version 5.5 (or later) or Netscape Communicator Version 4.76 (or later). The SSL_RSA_WITH_DES_CBC_SHA CipherSuite provides less security than the other CipherSuites, as it does not offer 128-bit encryption.

The more secure and more complex CipherSuites require slightly more processing time. This list defines the CipherSuites supported by the switch and ranks them from fastest to slowest in terms of router processing load (speed):

SSL_RSA_WITH_DES_CBC_SHA—RSA key exchange (RSA Public Key Cryptography) with DES-CBC for message encryption and SHA for message digest
SSL_RSA_WITH_NULL_SHA key exchange with NULL for message encryption and SHA for message digest (only for SSL 3.0).
SSL_RSA_WITH_NULL_MD5 key exchange with NULL for message encryption and MD5 for message digest (only for SSL 3.0).
SSL_RSA_WITH_RC4_128_MD5—RSA key exchange with RC4 128-bit encryption and MD5 for message digest
SSL_RSA_WITH_RC4_128_SHA—RSA key exchange with RC4 128-bit encryption and SHA for message digest
SSL_RSA_WITH_3DES_EDE_CBC_SHA—RSA key exchange with 3DES and DES-EDE3-CBC for message encryption and SHA for message digest
SSL_RSA_WITH_AES_128_CBC_SHA—RSA key exchange with AES 128-bit encryption and SHA for message digest (only for SSL 3.0).
SSL_RSA_WITH_AES_256_CBC_SHA—RSA key exchange with AES 256-bit encryption and SHA for message digest (only for SSL 3.0).
SSL_RSA_WITH_DHE_AES_128_CBC_SHA—RSA key exchange with AES 128-bit encryption and SHA for message digest (only for SSL 3.0).
SSL_RSA_WITH_DHE_AES_256_CBC_SHA—RSA key exchange with AES 256-bit encryption and SHA for message digest (only for SSL 3.0).

Note

The latest versions of Chrome do not support the four original cipher suites, thus disallowing access to both web GUI and guest portals.

RSA (in conjunction with the specified encryption and digest algorithm combinations) is used for both key generation and authentication on SSL connections. This usage is independent of whether or not a CA trustpoint is configured.

Default SSL Configuration

The standard HTTP server is enabled.

SSL is enabled.

No CA trustpoints are configured.

No self-signed certificates are generated.

SSL Configuration Guidelines

When SSL is used in a switch cluster, the SSL session terminates at the cluster commander. Cluster member switches must run standard HTTP.

Before you configure a CA trustpoint, you should ensure that the system clock is set. If the clock is not set, the certificate is rejected due to an incorrect date.

In a switch stack, the SSL session terminates at the stack master.

Configuring a CA Trustpoint

For secure HTTP connections, we recommend that you configure an official CA trustpoint. A CA trustpoint is more secure than a self-signed certificate.

Beginning in privileged EXEC mode, follow these steps to configure a CA Trustpoint:

SUMMARY STEPS

configure terminal
hostname hostname
ip domain-name domain-name
crypto key generate rsa
crypto ca trustpoint name
enrollment url url
enrollment http-proxy host-name port-number
crl query url
primary name
exit
crypto ca authentication name
crypto ca enroll name
end
show crypto ca trustpoints
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 2	hostname `hostname` Example: `Switch(config)# hostname your_hostname`	Specifies the hostname of the switch (required only if you have not previously configured a hostname). The hostname is required for security keys and certificates.
Step 3	ip domain-name `domain-name` Example: `Switch(config)# ip domain-name your_domain`	Specifies the IP domain name of the switch (required only if you have not previously configured an IP domain name). The domain name is required for security keys and certificates.
Step 4	crypto key generate rsa Example: `Switch(config)# crypto key generate rsa`	(Optional) Generates an RSA key pair. RSA key pairs are required before you can obtain a certificate for the switch. RSA key pairs are generated automatically. You can use this command to regenerate the keys, if needed.
Step 5	crypto ca trustpoint `name` Example: `Switch(config)# crypto ca trustpoint your_trustpoint`	Specifies a local configuration name for the CA trustpoint and enter CA trustpoint configuration mode.
Step 6	enrollment url `url` Example: `Switch(ca-trustpoint)# enrollment url http://your_server:80`	Specifies the URL to which the switch should send certificate requests.
Step 7	enrollment http-proxy `host-name` `port-number` Example: `Switch(ca-trustpoint)# enrollment http-proxy your_host 49`	(Optional) Configures the switch to obtain certificates from the CA through an HTTP proxy server. For `host-name` , specify the proxy server used to get the CA. For `port-number`, specify the port number used to access the CA.
Step 8	crl query `url` Example: `Switch(ca-trustpoint)# crl query ldap://your_host:49`	Configures the switch to request a certificate revocation list (CRL) to ensure that the certificate of the peer has not been revoked.
Step 9	primary `name` Example: `Switch(ca-trustpoint)# primary your_trustpoint`	(Optional) Specifies that the trustpoint should be used as the primary (default) trustpoint for CA requests. For `name`, specify the trustpoint that you just configured.
Step 10	exit Example: `Switch(ca-trustpoint)# exit`	Exits CA trustpoint configuration mode and return to global configuration mode.
Step 11	crypto ca authentication `name` Example: `Switch(config)# crypto ca authentication your_trustpoint`	Authenticates the CA by getting the public key of the CA. Use the same name used in Step 5.
Step 12	crypto ca enroll `name` Example: `Switch(config)# crypto ca enroll your_trustpoint`	Obtains the certificate from the specified CA trustpoint. This command requests a signed certificate for each RSA key pair.
Step 13	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 14	show crypto ca trustpoints Example: `Switch# show crypto ca trustpoints`	Verifies the configuration.
Step 15	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Configuring the Secure HTTP Server

Beginning in privileged EXEC mode, follow these steps to configure a secure HTTP server:

Before you begin

If you are using a certificate authority for certification, you should use the previous procedure to configure the CA trustpoint on the switch before enabling the HTTP server. If you have not configured a CA trustpoint, a self-signed certificate is generated the first time that you enable the secure HTTP server. After you have configured the server, you can configure options (path, access list to apply, maximum number of connections, or timeout policy) that apply to both standard and secure HTTP servers.

To verify the secure HTTP connection by using a Web browser, enter https://URL, where the URL is the IP address or hostname of the server switch. If you configure a port other than the default port, you must also specify the port number after the URL. For example:


https://209.165.129:1026

or


https://host.domain.com:1026

SUMMARY STEPS

show ip http server status
configure terminal
ip http secure-server
ip http secure-port port-number
ip http secure-ciphersuite {[3des-ede-cbc-sha ] [rc4-128-md5 ] [rc4-128-sha ] [des-cbc-sha ]}
ip http secure-client-auth
ip http secure-trustpoint name
ip http path path-name
ip http access-class access-list-number
ip http max-connections value
ip http timeout-policy idle seconds life seconds requests value
end
show ip http server secure status
copy running-config startup-config

DETAILED STEPS

Command or Action Purpose

Step 1

show ip http server status

Example:


Switch# show ip http server status

(Optional) Displays the status of the HTTP server to determine if the secure HTTP server feature is supported in the software. You should see one of these lines in the output:


HTTP secure server capability: Present

or


HTTP secure server capability: Not present

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

ip http secure-server

Example:


Switch(config)# ip http secure-server

Enables the HTTPS server if it has been disabled. The HTTPS server is enabled by default.

Step 4

ip http secure-port port-number

Example:


Switch(config)# ip http secure-port 443

(Optional) Specifies the port number to be used for the HTTPS server. The default port number is 443. Valid options are 443 or any number in the range 1025 to 65535.

Step 5

ip http secure-ciphersuite {[3des-ede-cbc-sha ] [rc4-128-md5 ] [rc4-128-sha ] [des-cbc-sha ]}

Example:


Switch(config)# ip http secure-ciphersuite rc4-128-md5

(Optional) Specifies the CipherSuites (encryption algorithms) to be used for encryption over the HTTPS connection. If you do not have a reason to specify a particularly CipherSuite, you should allow the server and client to negotiate a CipherSuite that they both support. This is the default.

Step 6

ip http secure-client-auth

Example:


Switch(config)# ip http secure-client-auth

(Optional) Configures the HTTP server to request an X.509v3 certificate from the client for authentication during the connection process. The default is for the client to request a certificate from the server, but the server does not attempt to authenticate the client.

Step 7

ip http secure-trustpoint name

Example:


Switch(config)# ip http secure-trustpoint your_trustpoint

Specifies the CA trustpoint to use to get an X.509v3 security certificate and to authenticate the client certificate connection.

Note

Use of this command assumes you have already configured a CA trustpoint according to the previous procedure.

Step 8

ip http path path-name

Example:


Switch(config)# ip http path /your_server:80

(Optional) Sets a base HTTP path for HTML files. The path specifies the location of the HTTP server files on the local system (usually located in system flash memory).

Step 9

ip http access-class access-list-number

Example:


Switch(config)# ip http access-class 2

(Optional) Specifies an access list to use to allow access to the HTTP server.

Step 10

ip http max-connections value

Example:


Switch(config)# ip http max-connections 4

(Optional) Sets the maximum number of concurrent connections that are allowed to the HTTP server. We recommend that the value be at least 10 and not less. This is required for the UI to function as expected.

Step 11

ip http timeout-policy idle seconds life seconds requests value

Example:


Switch(config)# ip http timeout-policy idle 120 life 240 requests 1

(Optional) Specifies how long a connection to the HTTP server can remain open under the defined circumstances:

idle —the maximum time period when no data is received or response data cannot be sent. The range is 1 to 600 seconds. The default is 180 seconds (3 minutes).
life —the maximum time period from the time that the connection is established. The range is 1 to 86400 seconds (24 hours). The default is 180 seconds.
requests —the maximum number of requests processed on a persistent connection. The maximum value is 86400. The default is 1.

Step 12

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 13

show ip http server secure status

Example:


Switch# show ip http server secure status

Displays the status of the HTTP secure server to verify the configuration.

Step 14

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring the Secure HTTP Client

Beginning in privileged EXEC mode, follow these steps to configure a secure HTTP client:

Before you begin

The standard HTTP client and secure HTTP client are always enabled. A certificate authority is required for secure HTTP client certification. This procedure assumes that you have previously configured a CA trustpoint on the switch. If a CA trustpoint is not configured and the remote HTTPS server requires client authentication, connections to the secure HTTP client fail.

SUMMARY STEPS

configure terminal
ip http client secure-trustpoint name
ip http client secure-ciphersuite {[3des-ede-cbc-sha ] [rc4-128-md5 ] [rc4-128-sha ] [des-cbc-sha ]}
end
show ip http client secure status
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 2	ip http client secure-trustpoint `name` Example: `Switch(config)# ip http client secure-trustpoint your_trustpoint`	(Optional) Specifies the CA trustpoint to be used if the remote HTTP server requests client authentication. Using this command assumes that you have already configured a CA trustpoint by using the previous procedure. The command is optional if client authentication is not needed or if a primary trustpoint has been configured.
Step 3	ip http client secure-ciphersuite {[3des-ede-cbc-sha ] [rc4-128-md5 ] [rc4-128-sha ] [des-cbc-sha ]} Example: `Switch(config)# ip http client secure-ciphersuite rc4-128-md5`	(Optional) Specifies the CipherSuites (encryption algorithms) to be used for encryption over the HTTPS connection. If you do not have a reason to specify a particular CipherSuite, you should allow the server and client to negotiate a CipherSuite that they both support. This is the default.
Step 4	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 5	show ip http client secure status Example: `Switch# show ip http client secure status`	Displays the status of the HTTP secure server to verify the configuration.
Step 6	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Monitoring Secure HTTP Server and Client Status

To monitor the SSL secure server and client status, use the privileged EXEC commands in the following table.

Table 11. Commands for Displaying the SSL Secure Server and Client Status
Command	Purpose
show ip http client secure status	Shows the HTTP secure client configuration.
show ip http server secure status	Shows the HTTP secure server configuration.
show running-config	Shows the generated self-signed certificate for secure HTTP connections.

Additional References

Error Message Decoder


Description	Link
To help you research and resolve system error messages in this release, use the Error Message Decoder tool.	https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi

Standards and RFCs


Standard/RFC	Title

MIBs


MIB	MIBs Link
All supported MIBs for this release.	To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

Technical Assistance


Description	Link
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.	http://www.cisco.com/support

Feature Information for SSL HTTP


Release	Feature Information
	This feature was introduced.

Related Topic	Document Title
Configuring Identity Control policies and Identity Service templates for Session Aware networking.	Session Aware Networking Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches) http://www.cisco.com/en/US/docs/ios-xml/ios/san/configuration/xe-3se/3850/san-xe-3se-3850-book.html
Configuring RADIUS, TACACS+, Secure Shell, 802.1X and AAA	Securing User Services Configuration Guide Library, Cisco IOS XE Release 3SE (Catalyst 3850 Switches) http://www.cisco.com/en/US/docs/ios-xml/ios/security/config_library/xe-3se/3850/secuser-xe-3se-3850-library.html
Kerberos Commands	Cisco IOS Security Command Reference, Release 12.4
Kerberos Configuration Examples	Cisco IOS Security Configuration Guide, Release 12.4.

Related Topic	Document Title
Configuring Identity Control policies and Identity Service templates for Session Aware networking.	Session Aware Networking Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches) http://www.cisco.com/en/US/docs/ios-xml/ios/san/configuration/xe-3se/3850/san-xe-3se-3850-book.html
Configuring RADIUS, TACACS+, Secure Shell, 802.1X and AAA.	Securing User Services Configuration Guide Library, Cisco IOS XE Release 3SE (Catalyst 3850 Switches) http://www.cisco.com/en/US/docs/ios-xml/ios/security/config_library/xe-3se/3850/secuser-xe-3se-3850-library.html

Related Topic	Document Title
Configuring Secure Shell” section in the “Other Security Features” chapter Secure Copy Protocol	Cisco IOS Security Configuration Guide Release 12.4
Secure Shell Commands	Cisco IOS Security Command Reference
For complete syntax and usage information for the commands	Cisco IOS IPv6 Command Reference

Bias-Free Language

Results

Chapter: Configuring Switch-Based Authentication

Configuring Switch-Based Authentication

Finding Feature Information

Preventing Unauthorized Access

Finding Feature Information

Restrictions for Controlling Switch Access with Passwords and Privileges

Default Password and Privilege Level Configuration

Additional Password Security

Password Recovery

Terminal Line Telnet Configuration

Username and Password Pairs

Privilege Levels

Privilege Levels on Lines

Command Privilege Levels

Setting or Changing a Static Enable Password

SUMMARY STEPS

DETAILED STEPS

Example:

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Protecting Enable and Enable Secret Passwords with Encryption

SUMMARY STEPS

DETAILED STEPS

Example:

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Disabling Password Recovery

Before you begin

SUMMARY STEPS

DETAILED STEPS

Example:

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What to do next

Setting a Telnet Password for a Terminal Line

Before you begin

SUMMARY STEPS

DETAILED STEPS

Example:

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Example:

Configuring Username and Password Pairs

SUMMARY STEPS

DETAILED STEPS

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Setting the Privilege Level for a Command

SUMMARY STEPS

DETAILED STEPS

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Changing the Default Privilege Level for Lines

SUMMARY STEPS

DETAILED STEPS

Example: