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This chapter describes how to access the ASA for system management through Telnet, SSH, and HTTPS (using ASDM), how to authenticate and authorize users, and how to create login banners.
This chapter includes the following sections:
Note To access the ASA interface for management access, you do not also need an access rule allowing the host IP address. You only need to configure management access according to the sections in this chapter.
This section describes how to allow clients to access the ASA using ASDM, Telnet, or SSH and includes the following topics:
The following table shows the licensing requirements for this feature:
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This section includes the guidelines and limitations for this feature.
Supported in single and multiple context mode.
Supported in routed and transparent firewall mode.
For the ASASM, a session from the switch to the ASASM is a Telnet session, but Telnet access configuration according to this section is not required.
– A maximum of 5 concurrent Telnet connections per context, if available, with a maximum of 100 connections divided among all contexts.
– A maximum of 5 concurrent SSH connections per context, if available, with a maximum of 100 connections divided among all contexts.
– A maximum of 5 concurrent ASDM instances per context, if available, with a maximum of 32 ASDM instances among all contexts.
To identify the client IP addresses allowed to connect to the ASA using Telnet, perform the following steps.
The following example shows how to let a host on the inside interface with an address of 192.168.1.2 access the ASA:
The following example shows how to allow all users on the 192.168.3.0 network to access the ASA on the inside interface:
To gain access to the ASA CLI using Telnet, enter the login password set by the password command. You must manually set the password before using Telnet. See Configuring the Hostname, Domain Name, and Passwords.
If you configure Telnet authentication (see Configuring Authentication for CLI and ASDM Access), then enter the username and password defined by the AAA server or local database.
To identify the client IP addresses and define a user allowed to connect to the ASA using SSH, perform the following steps:
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Generates an RSA key pair, which is required for SSH (for physical ASAs only). Note For the ASAv, the RSA key pairs are automatically created after deployment. The modulus value (in bits) is 512, 768, 1024, or 2048. The larger the key modulus size you specify, the longer it takes to generate an RSA key pair. We recommend a value of 1024. |
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Enables local authentication for SSH access. You can alternatively configure authentication using a AAA server. See Configuring Authentication for CLI and ASDM Access for more information. |
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Creates a user in the local database that can be used for SSH access. |
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For each address or subnet, identifies the IP addresses from which the ASA accepts connections, and the interface on which you can SSH. Unlike Telnet, you can SSH on the lowest security level interface. |
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(Optional) Sets the duration for how long an SSH session can be idle before the ASA disconnects the session. Set the timeout from 1 to 60 minutes. The default is 5 minutes. The default duration is too short in most cases, and should be increased until all pre-production testing and troubleshooting have been completed. |
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(Optional) Limits access to SSH version 1 or 2. By default, SSH allows both versions 1 and 2. |
The following example shows how to generate RSA keys and let a host on the inside interface with an address of 192.168.1.2 access the ASA:
The following example shows how to allow all users on the 192.168.3.0/24 network to access the ASA on the inside interface:
In the SSH client on your management host, enter the username and password that you configured in the Configuring SSH Access. When starting an SSH session, a dot (.) displays on the ASA console before the following SSH user authentication prompt appears:
The display of the dot does not affect the functionality of SSH. The dot appears at the console when generating a server key or decrypting a message using private keys during SSH key exchange before user authentication occurs. These tasks can take up to two minutes or longer. The dot is a progress indicator that verifies that the ASA is busy and has not hung.
You can alternatively configure a public key instead of using a password. See Adding a User Account to the Local Database.
To use ASDM, you need to enable the HTTPS server, and allow HTTPS connections to the ASA. HTTPS access is enabled as part of the factory default configuration or when you use the setup command. This section describes how to manually configure ASDM access.
The following example shows how to enable the HTTPS server and let a host on the inside interface with an address of 192.168.1.2 access ASDM:
The following example shows how to allow all users on the 192.168.3.0/24 network to access ASDM on the inside interface:
This section includes the following topics:
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This section includes the guidelines and limitations for this feature.
You can configure a message to display when a user connects to the ASA, before a user logs in, or before a user enters privileged EXEC mode.
After a banner is added, Telnet or SSH sessions to ASA may close if:
The following example shows how to add a message-of-the-day banner:
The CLI Prompt pane lets you customize the prompt used during CLI sessions. By default, the prompt shows the hostname of the ASA. In multiple context mode, the prompt also displays the context name. You can display the following items in the CLI prompt:
To customize the CLI prompt, enter the following commands:
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prompt {[ hostname ] [ context ] [ domain ] [ slot ] [ state ] [ priority ] [ cluster-unit ]} |
The console timeout sets how long a connection can remain in privileged EXEC mode or configuration mode; when the timeout is reached, the session drops into user EXEC mode. By default, the session does not time out. This setting does not affect how long you can remain connected to the console port, which never times out.
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Specifies the idle time in minutes (0 through 60) after which the privileged session ends. The default timeout is 0, which means the session does not time out. |
By default, you can send ICMP packets to any ASA interface using either IPv4 or IPv6. This section tells how to limit ICMP management access to the ASA. You can protect the ASA from attacks by limiting the addresses of hosts and networks that are allowed to have ICMP access to the ASA.
Note For allowing ICMP traffic through the ASA, see the firewall configuration guide.
This section includes the following topics:
ICMP in IPv6 functions the same as ICMP in IPv4. ICMPv6 generates error messages, such as ICMP destination unreachable messages and informational messages like ICMP echo request and reply messages. Additionally ICMP packets in IPv6 are used in the IPv6 neighbor discovery process and path MTU discovery.
We recommend that you always grant permission for the ICMP unreachable message type (type 3). Denying ICMP unreachable messages disables ICMP path MTU discovery, which can halt IPsec and PPTP traffic. See RFC 1195 and RFC 1435 for details about path MTU discovery.
If you configure ICMP rules, then the ASA uses a first match to the ICMP traffic followed by an implicit deny all entry. That is, if the first matched entry is a permit entry, the ICMP packet continues to be processed. If the first matched entry is a deny entry or an entry is not matched, the ASA discards the ICMP packet and generates a syslog message. An exception is when an ICMP rule is not configured; in that case, a permit statement is assumed.
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This section includes the guidelines and limitations for this feature.
Supported in single and multiple context mode.
Supported in routed and transparent firewall mode.
By default, you can send ICMP packets to any ASA interface using either IPv4 or IPv6.
To configure ICMP access rules, enter one of the following commands:
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Creates an IPv4 ICMP access rule. If you do not specify an icmp_type, all types are identified. You can enter the number or the name. To control ping, specify echo-reply (0) (ASA-to-host) or echo (8) (host-to-ASA). See ICMP Types for a list of ICMP types. |
ciscoasa(config)# icmp permit host fe80::20d:88ff:feee:6a82 outside |
Creates an IPv6 ICMP access rule. If you do not specify an icmp_type, all types are identified. You can enter the number or the name. To control ping, specify echo-reply (0) (ASA-to-host) or echo (8) (host-to-ASA). SeeICMP Types for a list of ICMP types. |
The following example shows how to allow all hosts except the one at 10.1.1.15 to use ICMP to the inside interface:
The following example shows how to allow the host at 10.1.1.15 to use only ping to the inside interface, enter the following command:
The following example shows how to deny all ping requests and permit all packet-too-big messages (to support path MTU discovery) at the outside interface:
The following example shows how to permit host 2000:0:0:4::2 or hosts on prefix 2001::/64 to ping the outside interface:
If your VPN tunnel terminates on one interface, but you want to manage the ASA by accessing a different interface, you can identify that interface as a management-access interface. For example, if you enter the ASA from the outside interface, this feature lets you connect to the inside interface using ASDM, SSH, Telnet, or SNMP; or you can ping the inside interface when entering from the outside interface. Management access is available via the following VPN tunnel types: IPsec clients, IPsec site-to-site, and the AnyConnect SSL VPN client.
This section includes the following topics:
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This section includes the guidelines and limitations for this feature.
You can define only one management access interface.
Note For the configurations that follow, 192.168.10.0/24 is the VPN pool for AnyConnect or IPsec VPN clients. Each configuration allows VPN client users to connect to ASDM or SSH to the ASA using the management interface IP address.
To allow only VPN client users access to ASDM or HTTP (and deny access to all other users), enter the following commands:
To allow only VPN client users access to the ASA using SSH (and deny access to all other users), enter the following command:
To configure the management interface, perform the following steps.
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management-access management_interface |
The management_interface specifies the name of the management interface that you want to access when entering the ASA from another interface. |
This section describes how to enable authentication and command authorization for system administrators.
This section describes AAA for system administrators and includes the following topics:
This section describes authentication for management access and includes the following topics:
How you log into the ASA depends on whether or not you enable authentication:
To enter privileged EXEC mode after logging in, enter the enable command. How enable works depends on whether you enable authentication:
For enable authentication using the local database, you can use the login command instead of the enable command. login maintains the username but requires no configuration to turn on authentication. See Authenticating Users with the login Command for more information.
By default, you can log into ASDM with a blank username and the enable password set by the enable password command. Note that if you enter a username and password at the login screen (instead of leaving the username blank), ASDM checks the local database for a match.
If you configure HTTP authentication, you can no longer use ASDM with a blank username and the enable password.
For sessions from the switch to the ASASM (using the session command), you can configure Telnet authentication. For virtual console connections from the switch to the ASASM (using the service-module session command), you can configure serial port authentication.
In multiple context mode, you cannot configure any AAA commands in the system configuration. However, if you configure Telnet or serial authentication in the admin context, then authentication also applies to sessions from the switch to the ASASM. The admin context AAA server or local user database is used in this instance.
This section describes command authorization and includes the following topics:
You can use one of two command authorization methods:
Note You can use local command authorization without any users in the local database and without CLI or enable authentication. Instead, when you enter the enable command, you enter the system enable password, and the ASA places you in level 15. You can then create enable passwords for every level, so that when you enter enable n (2 to 15), the ASA places you in level n. These levels are not used unless you enable local command authorization (see Configuring Local Command Authorization). (See the command reference for more information about the enable command.)
When a user logs into the ASA, that user is required to provide a username and password for authentication. The ASA retains these session credentials in case further authentication is needed later in the session.
When the following configurations are in place, a user needs only to authenticate with the local server for login. Subsequent serial authorization uses the saved credentials. The user is also prompted for the privilege level 15 password. When exiting privileged mode, the user is authenticated again. User credentials are not retained in privileged mode.
The following table shows how credentials are used in this case by the ASA.
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The following are important points to consider when implementing command authorization with multiple security contexts:
When configuring command authorization, you must configure each security context separately. This configuration provides you the opportunity to enforce different command authorizations for different security contexts.
When switching between security contexts, administrators should be aware that the commands permitted for the username specified when they login may be different in the new context session or that command authorization may not be configured at all in the new context. Failure to understand that command authorizations may differ between security contexts could confuse an administrator. This behavior is further complicated by the next point.
This behavior also affects command accounting, which is useful only if you can accurately associate each command that is issued with a particular administrator. Because all administrators with permission to use the changeto command can use the enable_15 username in other contexts, command accounting records may not readily identify who was logged in as the enable_15 username. If you use different accounting servers for each context, tracking who was using the enable_15 username requires correlating the data from several servers.
When configuring command authorization, consider the following:
When switching between security contexts, administrators can exit privileged EXEC mode and enter the enable command again to use the username that they need.
Note The system execution space does not support AAA commands; therefore, command authorization is not available in the system execution space.
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Prerequisites for the AAA Server or Local Database
You must configure users in a AAA server or the local database. For a AAA server, you then need to configure the ASA to communicate with it. See the following chapters:
Prerequisites for Management Authentication
Before the ASA can authenticate a Telnet, SSH, or HTTP user, you must identify the IP addresses that are allowed to communicate with the ASA. For the ASASM, the exception is for access to the system in multiple context mode; a session from the switch to the ASASM is a Telnet session, but Telnet access configuration is not required. For more information, see Configuring ASA Access for ASDM, Telnet, or SSH.
Prerequisites for Local Command Authorization
enable authentication is essential for maintaining the username after the user accesses the enable command.
Alternatively, you can use the login command (which is the same as the enable command with authentication; for the local database only), which requires no configuration. We do not recommend this option because it is not as secure as enable authentication.
You can also use CLI authentication, but it is not required.
– Local database users—Configure each user in the local database at a privilege level from 0 to 15.
– RADIUS users—Configure the user with Cisco VSA CVPN3000-Privilege-Level with a value between 0 and 15.
– LDAP users—Configure the user with a privilege level between 0 and 15, and then map the LDAP attribute to Cisco VSA CVPN3000-Privilege-Level according to the Configuring LDAP Attribute Maps.
Prerequisites for TACACS+ Command Authorization
Prerequisites for Management Accounting
This section includes the guidelines and limitations for this feature.
Supported in single and multiple context mode.
Default Command Privilege Levels
By default, the following commands are assigned to privilege level 0. All other commands are assigned to privilege level 15.
If you move any configure mode commands to a lower level than 15, be sure to move the configure command to that level as well, otherwise, the user will not be able to enter configuration mode.
To view all privilege levels, see Viewing Local Command Privilege Levels.
You can require authentication for CLI, ASDM, and enable command access.
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aaa authentication { telnet | ssh | http | serial } console { LOCAL | server_group [ LOCAL ]} ciscoasa(config)# aaa authentication ssh console radius_1 LOCAL ciscoasa(config)# aaa authentication http console radius_1 LOCAL |
Authenticates users for management access. The telnet keyword controls Telnet access. For the ASASM, this keyword also affects the session from the switch using the session command. For multiple mode access, see Authenticating Sessions from the Switch to the ASA Services Module. The ssh keyword controls SSH access. The http keyword controls ASDM access. The serial keyword controls console port access. For the ASASM, this keyword affects the virtual console accessed from the switch using the service-module session command. For multiple mode access, see Authenticating Sessions from the Switch to the ASA Services Module. HTTP management authentication does not support the SDI protocol for a AAA server group. If you use a AAA server group for authentication, you can configure the ASA to use the local database as a fallback method if the AAA server is unavailable. Specify the server group name followed by LOCAL (LOCAL is case sensitive). We recommend that you use the same username and password in the local database as the AAA server, because the ASA prompt does not give any indication which method is being used. You can alternatively use the local database as your primary method of authentication (with no fallback) by entering LOCAL alone. |
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http authentication-certificate interface |
Requires a certificate from ASDM clients connecting over HTTP on the specified interface. This command can be used in addition to the aaa authentication command for ASDM. This command is only for ASDM access, use the command ssl certificate-authentication to require a certificate for all other SSL traffic, for example, cut-through proxy. |
You can configure the ASA to authenticate users with a AAA server or the local database when they enter the enable command. Alternatively, users are automatically authenticated with the local database when they enter the login command, which also accesses privileged EXEC mode depending on the user level in the local database.
You can configure the ASA to authenticate users when they enter the enable command. See Comparing CLI Access with and without Authentication for more information.
To authenticate users who enter the enable command, enter the following command.
From user EXEC mode, you can log in as any username in the local database using the login command.
This feature allows users to log in with their own username and password to access privileged EXEC mode, so you do not have to provide the system enable password to everyone. To allow users to access privileged EXEC mode (and all commands) when they log in, set the user privilege level to 2 (the default) through 15. If you configure local command authorization, then the user can only enter commands assigned to that privilege level or lower. See Configuring Local Command Authorization for more information.
To log in as a user from the local database, enter the following command:
The ASA enables you to distinguish between administrative and remote-access users when they authenticate using RADIUS, LDAP, TACACS+, or the local user database. User role differentiation can prevent remote access VPN and network access users from establishing an administrative connection to the ASA.
Note Serial access is not included in management authorization, so if you configure the aaa authentication serial consolecommand, then any user who authenticates can access the console port.
Step 1 To enable management authorization for local, RADIUS, LDAP (mapped), and TACACS+ users, enter the following command:
ciscoasa(config)# aaa authorization exec { authentication-server | LOCAL } [ auto-enable ]
When the LOCAL option is configured, the local user database is the source for the username entered and the Service-Type and Privilege-Level attributes assigned.
This option also enables support of administrative user privilege levels from RADIUS, which can be used in conjunction with local command privilege levels for command authorization. See Configuring Local Command Authorization for more information.
When the authentication-server option is configured, the same server is used for both authentication and authorization.
The auto-enable option allows users with sufficient privileges from the login authentication server to be placed directly in privileged EXEC mode. Otherwise, users are placed in user EXEC mode. These privileges are determined by the Service-Type and Privilege-Level attributes that are required to enter each EXEC mode. To enter privileged EXEC mode, users must have a Service-Type attribute of Administrative and a Privilege Level attribute of greater than 1 assigned to them.
This option is not supported in the system context. However, if you configure Telnet or serial authentication in the admin context, then authentication also applies to sessions from the switch to the ASASM.
There is no effect if you enter the aaa authorization exec command alone.
The auto-enable option is not included when you use serial authentication in management authorization.
The aaa authentication http command is not affected by the auto-enable option.
Before you configure the auto-enable option, we recommend that you configure both protocol login and enable authentication, and that all authentication requests go to the same AAA server group, as shown in the following example:
We do not recommend that you use other types of configurations.
Step 2 To configure the user for management authorization, see the following requirements for each AAA server type or local user:
When users are authenticated through LDAP, the native LDAP attributes and their values can be mapped to Cisco ASA attributes to provide specific authorization features. Configure Cisco VSA CVPN3000-Privilege-Level with a value between 0 and 15. and then map the LDAP attributes to Cisco VAS CVPN3000-Privilege-Level using the ldap map-attributes command. For more information, see Configuring LDAP Attribute Maps.
The RADIUS IETF service-type attribute, when sent in an access-accept message as the result of a RADIUS authentication and authorization request, is used to designate which type of service is granted to the authenticated user:
The RADIUS Cisco VSA privilege-level attribute (Vendor ID 3076, sub-ID 220), when sent in an access-accept message, is used to designate the level of privilege for the user.
When an authenticated user tries administrative access to the ASA through ASDM, SSH, or Telnet, but does not have the appropriate privilege level to do so, the ASA generates syslog message 113021. This message informs the user that the attempted login failed because of inappropriate administrative privileges.
The following example shows how to define an LDAP attribute map. In this example, the security policy specifies that users being authenticated through LDAP map the user record fields or parameters title and company to the IETF-RADIUS service-type and privilege-level, respectively.
ciscoasa(config)#
ldap attribute-map admin-control
ciscoasa(config-ldap-attribute-map)#
map-name title IETF-RADIUS-Service-Type
ciscoasa(config-ldap-attribute-map)#
map-name company Privilege-Level
The following example applies an LDAP attribute map to an LDAP AAA server:
ciscoasa(config)#
aaa-server ldap-server (dmz1) host 10.20.30.1
ciscoasa(config-aaa-server-host)#
ldap-attribute-map admin-control
Authorization is requested with “service=shell,” and the server responds with PASS or FAIL.
Set the service-type command for a given username. By default, the service-type is admin, which allows full access to any services specified by the aaa authentication console command. For more information, see Adding a User Account to the Local Database.
When you configure authentication for CLI or ASDM access using the local database, you can configure a password policy that requires a user to change their password after a specified amount of time and also requires password standards such as a minimum length and the minimum number of changed characters.
The password policy only applies to administrative users using the local database, and not to other types of traffic that can use the local database, such as VPN or AAA for network access, and not to users authenticated by a AAA server.
After you configure the password policy, when you change a password (either your own or another user’s), the password policy applies to the new password. Any existing passwords are grandfathered in. The new policy applies to changing the password with the username command as well as the change-password command.
If you configure a password lifetime in the password policy, you need to change your username password to a new one when the old password expires. This password change method is required if you enable password policy authentication (the password-policy authenticate enable command). If password policy authentication is not enabled, then you can use this method, or you can change your user account directly with the username command.
If you want to control access to commands, the ASA lets you configure command authorization, where you can determine which commands that are available to a user. By default when you log in, you can access user EXEC mode, which offers only minimal commands. When you enter the enable command (or the login command when you use the local database), you can access privileged EXEC mode and advanced commands, including configuration commands.
You can use one of two command authorization methods:
For more information about command authorization, see Information About Command Authorization.
Local command authorization lets you assign commands to one of 16 privilege levels (0 to 15). By default, each command is assigned either to privilege level 0 or 15. You can define each user to be at a specific privilege level, and each user can enter any command at the assigned privilege level or below. The ASA supports user privilege levels defined in the local database, a RADIUS server, or an LDAP server (if you map LDAP attributes to RADIUS attributes). See the following sections for more information:
To configure local command authorization, perform the following steps:
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Assigns a command to a privilege level. Repeat this command for each command that you want to reassign. The options in this command are the following:
– enable —Specifies both user EXEC mode and privileged EXEC mode. – configure —Specifies configuration mode, accessed using the configure terminal command. |
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aaa authorization exec authentication-server ciscoasa(config)# aaa authorization exec authentication-server |
Supports administrative user privilege levels from RADIUS. Enforces user-specific access levels for users who authenticate for management access (see the aaa authentication console LOCAL command). Without this command, the ASA only supports privilege levels for local database users and defaults all other types of users to level 15. This command also enables management authorization for local, RADIUS, LDAP (mapped), and TACACS+ users. Use the aaa authorization exec LOCAL command to enable attributes to be taken from the local database. See Limiting User CLI and ASDM Access with Management Authorization for information about configuring a user on a AAA server to accommodate management authorization. |
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aaa authorization command LOCAL |
Enables the use of local command privilege levels, which can be checked with the privilege level of users in the local database, RADIUS server, or LDAP server (with mapped attributes). When you set command privilege levels, command authorization does not occur unless you configure command authorization with this command. |
The filter command has the following forms:
You can set the privilege level separately for each form, or set the same privilege level for all forms by omitting this option. The following example shows how to set each form separately:
Alternatively, the following example shows how to set all filter commands to the same level:
The show privilege command separates the forms in the display.
The following example shows the use of the mode keyword. The enable command must be entered from user EXEC mode, while the enable password command, which is accessible in configuration mode, requires the highest privilege level:
The following example shows an additional command, the configure command, which uses the mode keyword:
Note This last line is for the configure terminal command.
The following commandslet you view privilege levels for commands.
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Shows commands for a specific level. The level is an integer between 0 and 15. |
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For the show running-config all privilege all command, the ASA displays the current assignment of each CLI command to a privilege level. The following is sample output from this command:
The following example shows the command assignments for privilege level 10:
The following example shows the command assignments for the access-list command:
You can configure commands on a Cisco Secure Access Control Server (ACS) TACACS+ server as a shared profile component, for a group, or for individual users. For third-party TACACS+ servers, see your server documentation for more information about command authorization support.
See the following guidelines for configuring commands in Cisco Secure ACS Version 3.1; many of these guidelines also apply to third-party servers:
Note Cisco Secure ACS might include a command type called “pix-shell.” Do not use this type for ASA command authorization.
For example, to allow the show running-configuration aaa-server command, add show running-configuration to the command field, and type permit aaa-server in the arguments field.
For example, you can configure just the show command, then all the show commands are allowed. We recommend using this method so that you do not have to anticipate every variant of a command, including abbreviations and a question mark, which shows CLI usage.
For example, to allow enable, but not enable password, enter enable in the commands field, and deny password in the arguments field. Be sure to check the Permit Unmatched Args check box so that enable alone is still allowed.
For example, if you enter sh log, then the ASA sends the entire command to the TACACS+ server, show logging. However, if you enter sh log mess, then the ASA sends show logging mess to the TACACS+ server, and not the expanded command show logging message. You can configure multiple spellings of the same argument to anticipate abbreviations.
If you enable TACACS+ command authorization, and a user enters a command at the CLI, the ASA sends the command and username to the TACACS+ server to determine if the command is authorized.
Before you enable TACACS+ command authorization, be sure that you are logged into the ASA as a user that is defined on the TACACS+ server, and that you have the necessary command authorization to continue configuring the ASA. For example, you should log in as an admin user with all commands authorized. Otherwise, you could become unintentionally locked out.
Do not save your configuration until you are sure that it works the way you want. If you get locked out because of a mistake, you can usually recover access by restarting the ASA. If you still get locked out, see Recovering from a Lockout.
Be sure that your TACACS+ system is completely stable and reliable. The necessary level of reliability typically requires that you have a fully redundant TACACS+ server system and fully redundant connectivity to the ASA. For example, in your TACACS+ server pool, include one server connected to interface 1, and another to interface 2. You can also configure local command authorization as a fallback method if the TACACS+ server is unavailable. In this case, you need to configure local users and command privilege levels according to procedures listed in the Configuring Command Authorization.
To configure TACACS+ command authorization, enter the following command:
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aaa authorization command tacacs+_server_group [ LOCAL ] |
Performs command authorization using a TACACS+ server. You can configure the ASA to use the local database as a fallback method if the TACACS+ server is unavailable. To enable fallback, specify the server group name followed by LOCAL (LOCAL is case sensitive). We recommend that you use the same username and password in the local database as the TACACS+ server because the ASA prompt does not give any indication which method is being used. Be sure to configure users in the local database (see “Adding a User Account to the Local Database”) and command privilege levels (see Configuring Local Command Authorization). |
You can send accounting messages to the TACACS+ accounting server when you enter any command other than show commands at the CLI. You can configure accounting when users log in, when they enter the enable command, or when they issue commands.
For command accounting, you can only use TACACS+ servers.
To configure management access and enable command accounting, perform the following steps:
To view the current logged-in user, enter the following command:
The following is sample output from the show curpriv command:
Table 43-1 describes the show curpriv command output.
You can establish a maximum number of simultaneous management sessions. If the maximum is reached, no additional sessions are allowed and a syslog message is generated. To prevent a system lockout, the management session quota mechanism cannot block a console session.
To set a management session quota, enter the following command:
The Diffie-Hellman (DH) key exchange provides a shared secret that cannot be determined by either party alone. The key exchange is combined with a signature and the host key to provide host authentication. This key-exchange method provides explicit server authentication.
Both the DH Group 1 and Group 14 key-exchange methods for key exchange are supported on the ASA. If no DH group key-exchange method is specified, the DH group 1 key-exchange method is used. For more information about using DH key-exchange methods, see RFC 4253.
To exchange keys in an SSH session, enter the following command:
In some circumstances, when you turn on command authorization or CLI authentication, you can be locked out of the ASA CLI. You can usually recover access by restarting the ASA. However, if you already saved your configuration, you might be locked out. Table 43-2 lists the common lockout conditions and how you might recover from them.
Table 43-3 lists each feature change and the platform release in which it was implemented.