Management Access

This chapter describes how to access the Cisco ASA for system management through Telnet, SSH, and HTTPS (using ASDM), how to authenticate and authorize users, and how to create login banners.

Configure Management Remote Access

This section describes how to configure ASA access for ASDM, Telnet, or SSH, and other management parameters such as a login banner.

Configure SSH Access

To identify the client IP addresses and define a user allowed to connect to the ASA using SSH, perform the following steps. See the following guidelines:

  • To access the ASA interface for SSH access, you do not also need an access rule allowing the host IP address. You only need to configure SSH access according to this section.

  • SSH access to an interface other than the one from which you entered the ASA is not supported. For example, if your SSH host is located on the outside interface, you can only initiate a management connection directly to the outside interface. The only exception to this rule is through a VPN connection. See Configure Management Access Over a VPN Tunnel.

  • The ASA allows a maximum of 5 concurrent SSH connections per context/single mode, with a maximum of 100 connections divided among all contexts. However, because configuration commands might obtain locks on resources being changed, you should make changes in one SSH session at a time to ensure all changes are applied correctly.

  • (8.4 and later) The SSH default username is no longer supported. You can no longer connect to the ASA using SSH with the pix or asa username and the login password. To use SSH, you must configure AAA authentication using the aaa authentication ssh console LOCAL command; then define a local user by entering the username command. If you want to use a AAA server for authentication instead of the local database, we recommend also configuring local authentication as a backup method.

Before you begin

  • In multiple context mode, complete this procedure in the context execution space. To change from the system to a context configuration, enter changeto context name .

Procedure

Step 1

Generate an RSA key pair, which is required for SSH (for physical ASAs only).

crypto key generate rsa modulussize

  • size —The size in bits is 512, 768, 1024, 2048, or 4096. We recommend a value of at least 2048. The larger the key size you specify, the longer it takes to generate a key pair.

For the ASAv, the key pairs are automatically created after deployment.

Example:


ciscoasa(config)# crypto key generate rsa modulus 4096
Step 2

Save the keys to persistent flash memory.

write memory

Example:


ciscoasa(config)# write memory
Step 3

Create a user in the local database that can be used for SSH access. You can alternatively use a AAA server for user access, but a local username is recommended.

username name [password password] privilege level

Example:


ciscoasa(config)# username admin password Far$cape1999 privilege 15

By default, the privilege level is 2; enter a level between 0 and 15, where 15 has all privileges. You might want to create a user without a password if you want to force the user to use public key authentication (ssh authentication ) instead of password authentication. If you configure public key authentication as well as a password in the username command, then the user can log in with either method. Note: Do not use the username command nopassword option; the nopassword option allows any password to be entered, not no password.

Step 4

(Optional) Allow public key authentication for a user instead of/as well as password authentication, and enter the public key on the ASA:

username name attributes

ssh authentication {pkf | publickey key}

Example:


ciscoasa(config)# username admin attributes
ciscoasa(config-username)# ssh authentication pkf

Enter an SSH public key formatted file.
End with the word "quit" on a line by itself:
---- BEGIN SSH2 PUBLIC KEY ----
Comment: "4096-bit RSA, converted by xxx@xxx from OpenSSH"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---- END SSH2 PUBLIC KEY ----
quit
INFO: Import of an SSH public key formatted file SUCCEEDED.

For a local username , you can enable public key authentication instead of/as well as password authentication. You can generate a public key/private key pair using any SSH key generation software (such as ssh keygen) that can generate ssh-rsa raw keys (with no certificates). Enter the public key on the ASA. The SSH client then uses the private key (and the passphrase you used to create the key pair) to connect to the ASA.

For a pkf key, you are prompted to paste in a PKF formatted key, up to 4096 bits. Use this format for keys that are too large to paste inline in Base64 format. For example, you can generate a 4096-bit key using ssh keygen, then convert it to PKF, and use the pkf keyword to be prompted for the key. Note: You can use the pkf option with failover, but the PKF key is not automatically replicated to the standby system. You must enter the write standby command to synchronize the PKF key.

For a publickey key , the key is a Base64-encoded public key. You can generate the key using any SSH key generation software (such as ssh keygen) that can generate ssh-rsa raw keys (with no certificates).

Step 5

Enable local authentication for SSH access:

aaa authentication ssh console LOCAL

Example:


ciscoasa(config)# aaa authentication ssh console LOCAL

You can alternatively configure authentication using a AAA server. However, for public key authentication, only the LOCAL database is supported.

Step 6

Identify the IP addresses from which the ASA accepts connections for each address or subnet, and the interface on which you can use SSH.

ssh source_IP_address mask source_interface

  • source_interface —Specify any named interface. For bridge groups, specify the bridge group member interface.

Unlike Telnet, you can SSH on the lowest security level interface.

Example:


ciscoasa(config)# ssh 192.168.3.0 255.255.255.0 inside
Step 7

(Optional) Set the duration for how long an SSH session can be idle before the ASA disconnects the session.

ssh timeout minutes

Example:


ciscoasa(config)# ssh timeout 30

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.

Step 8

(Optional) Limit access to SSH version 1 or 2. By default, SSH allows both versions 1 and 2.

ssh version version_number

Example:


ciscoasa(config)# ssh version 2
Step 9

(Optional) Configure SSH cipher encryption algorithms:

ssh cipher encryption {all | fips | high | low | medium | custom colon-delimited_list_of_encryption_ciphers}

Example:


ciscoasa(config)# ssh cipher encryption custom 3des-cbc:aes128-cbc:aes192-cbc

The default is medium . Ciphers are used in the order they are listed. For pre-defined lists, they are listed from lowest to highest security.

  • The all keyword specifies using all ciphers: 3des-cbc aes128-cbc aes192-cbc aes256-cbc aes128-ctr aes192-ctr aes256-ctr

  • The custom keyword specifies a custom cipher encryption configuration string, separated by colons.

  • The fips keyword specifies only FIPS-compliant ciphers: aes128-cbc aes256-cbc

  • The high keyword specifies only high-strength ciphers: aes256-cbc aes256-ctr

  • The low keyword specifies low, medium, and high strength ciphers: 3des-cbc aes128-cbc aes192-cbc aes256-cbc aes128-ctr aes192-ctr aes256-ctr

  • The medium keyword specifies the medium and high strength ciphers (the default): 3des-cbc aes128-cbc aes192-cbc aes256-cbc aes128-ctr aes192-ctr aes256-ctr

Step 10

(Optional) Configure SSH cipher integrity algorithms:

ssh cipher integrity {all | fips | high | low | medium | custom colon-delimited_list_of_integrity_ciphers}

Example:


ciscoasa(config)# ssh cipher integrity custom hmac-sha1-96:hmac-md5

The default is medium .

  • The all keyword specifies using all ciphers: hmac-sha1 hmac-sha1-96 hmac-md5 hmac-md5-96

  • The custom keyword specifies a custom cipher encryption configuration string, separated by colons.

  • The fips keyword specifies only FIPS-compliant ciphers: hmac-sha1

  • The high keyword specifies only high-strength ciphers: hmac-sha1

  • The low keyword specifies low, medium, and high strength ciphers: hmac-sha1 hmac-sha1-96 hmac-md5 hmac-md5-96

  • The medium keyword specifies the medium and high strength ciphers (the default): hmac-sha1 hmac-sha1-96

Step 11

(Optional) Set the Diffie-Hellman (DH) key exchange mode:

ssh key-exchange group {dh-group1-sha1 | dh-group14-sha1}

Example:


ciscoasa(config)# ssh key-exchange group dh-group14-sha1

The default is dh-group1-sha1

The 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. For more information about using DH key-exchange methods, see RFC 4253.

Examples

The following example shows how to authenticate using a PKF formatted key: 


ciscoasa(config)# crypto key generate rsa modulus 4096
ciscoasa(config)# write memory
ciscoasa(config)# username exampleuser1 password examplepassword1 privilege 15
ciscoasa(config)# username exampleuser1 attributes
ciscoasa(config-username)# ssh authentication pkf
Enter an SSH public key formatted file.
End with the word "quit" on a line by itself:
---- BEGIN SSH2 PUBLIC KEY ----
Comment: "4096-bit RSA, converted by xxx@xxx from OpenSSH"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---- END SSH2 PUBLIC KEY ----
quit
INFO: Import of an SSH public key formatted file SUCCEEDED.
ciscoasa(config-username)# aaa authentication ssh console LOCAL
ciscoasa(config)#

The following example generates a shared key for SSH on a Linux or Macintosh system, and imports it to the ASA:

  1. Generate the RSA public and private keys for 4096 bits on your computer: 

    
jcrichton-mac:~ john$ ssh-keygen -b 4096
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/john/.ssh/id_rsa):
/Users/john/.ssh/id_rsa already exists.
Overwrite (y/n)? y
Enter passphrase (empty for no passphrase): pa$$phrase
Enter same passphrase again: pa$$phrase
Your identification has been saved in /Users/john/.ssh/id_rsa.
Your public key has been saved in /Users/john/.ssh/id_rsa.pub.
The key fingerprint is:
c0:0a:a2:3c:99:fc:00:62:f1:ee:fa:f8:ef:70:c1:f9 john@jcrichton-mac
The key's randomart image is:
+--[ RSA 4096]----+
| .               |
|  o  .           |
|+...  o          |
|B.+.....         |
|.B ..+  S        |
|  =   o          |
|   + . E         |
|  o o            |
| ooooo           |
+-----------------+

  2. Convert the key to PKF format: 

    
jcrichton-mac:~ john$ cd .ssh
jcrichton-mac:.ssh john$ ssh-keygen -e -f id_rsa.pub
---- BEGIN SSH2 PUBLIC KEY ----
Comment: "4096-bit RSA, converted by john@jcrichton-mac from OpenSSH"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---- END SSH2 PUBLIC KEY ----
jcrichton-mac:.ssh john$

  3. Copy the key to your clipboard.

  4. In ASDM, choose Configuration > Device Management > Users/AAA > User Accounts, select the username and then click Edit. Click Public Key Using PKF and paste the key into the window:

  5. Verify the user can SSH to the ASA. For the password, enter the SSH key password you specified when you created the key pair. 

    
jcrichton-mac:.ssh john$ ssh test@10.86.118.5
The authenticity of host '10.86.118.5 (10.86.118.5)' can't be established.
RSA key fingerprint is 39:ca:ed:a8:75:5b:cc:8e:e2:1d:96:2b:93:b5:69:94.
Are you sure you want to continue connecting (yes/no)? yes

    The following dialog box appears for you to enter your passphrase:

    Meanwhile, in the terminal session: 

    
Warning: Permanently added '10.86.118.5' (RSA) to the list of known hosts.
Identity added: /Users/john/.ssh/id_rsa (/Users/john/.ssh/id_rsa)
Type help or '?' for a list of available commands.
asa>

Configure Telnet Access

To identify the client IP addresses allowed to connect to the ASA using Telnet, perform the following steps. See the following guidelines:

  • To access the ASA interface for Telnet access, you do not also need an access rule allowing the host IP address. You only need to configure Telnet access according to this section.

  • Telnet access to an interface other than the one from which you entered the ASA is not supported. For example, if your Telnet host is located on the outside interface, you can only initiate a Telnet connection directly to the outside interface. The only exception to this rule is through a VPN connection. See Configure Management Access Over a VPN Tunnel.

  • You cannot use Telnet to the lowest security interface unless you use Telnet inside a VPN tunnel.

  • The ASA allows a maximum of 5 concurrent Telnet connections per context/single mode, with a maximum of 100 connections divided among all contexts.

Before you begin

  • In multiple context mode, complete this procedure in the context execution space. To change from the system to a context configuration, enter changeto context name .

  • 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.

Procedure

Step 1

Identify the IP addresses from which the ASA accepts connections for each address or subnet on the specified interface.

telnet source_IP_address mask source_interface

  • source_interface —Specify any named interface. For bridge groups, specify the bridge group member interface.

If there is only one interface, you can configure Telnet to access that interface as long as the interface has a security level of 100.

Example:


ciscoasa(config)# telnet 192.168.1.2 255.255.255.255 inside
Step 2

Set the duration for how long a Telnet session can be idle before the ASA disconnects the session.

telnet timeout minutes

Example:


ciscoasa(config)#  telnet timeout 30

Set the timeout from 1 to 1440 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.

Examples

The following example shows how to let a host on the inside interface with an address of 192.168.1.2 access the ASA: 


ciscoasa(config)# telnet 192.168.1.2 255.255.255.255 inside

The following example shows how to allow all users on the 192.168.3.0 network to access the ASA on the inside interface: 


ciscoasa(config)# telnet 192.168.3.0. 255.255.255.255 inside

Configure HTTPS Access for ASDM, Other Clients

To use ASDM or other HTTPS clients such as CSM, 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. To configure HTTPS access, perform the following steps. See the following guidelines:

  • To access the ASA interface for HTTPS access, you do not also need an access rule allowing the host IP address. You only need to configure HTTPS access according to this section. If, however, you configure HTTP redirect to redirect HTTP connections to HTTPS automatically, you must enable an access rule to allow HTTP; otherwise, the interface cannot listen to the HTTP port.

  • Management access to an interface other than the one from which you entered the ASA is not supported. For example, if your management host is located on the outside interface, you can only initiate a management connection directly to the outside interface. The only exception to this rule is through a VPN connection. See Configure Management Access Over a VPN Tunnel.

  • In single context mode, you can have a maximum 30 ASDM concurrent sessions. In multiple context mode, you can have a maximum of 5 concurrent ASDM sessions per context, with a maximum of 32 ASDM instances among all contexts.

    ASDM sessions use two HTTPS connections: one for monitoring that is always present, and one for making configuration changes that is present only when you make changes. For example, the multiple-context mode system limit of 32 ASDM sessions represents a limit of 64 HTTPS sessions.

  • The ASA allows a maximum of 6 concurrent non-ASDM HTTPS sessions in single context mode or per context, if available, with a maximum or 100 HTTPS sessions among all contexts.

Before you begin

  • In multiple context mode, complete this procedure in the context execution space. To change from the system to a context configuration, enter changeto context name .

Procedure

Step 1

Identify the IP addresses from which the ASA accepts HTTPS connections for each address or subnet on the specified interface.

http source_IP_address mask source_interface

  • source_interface —Specify any named interface. For bridge groups, specify the bridge group member interface.

Example:


ciscoasa(config)# http 192.168.1.2 255.255.255.255 inside
Step 2

Enable the HTTPS server.

http server enable [port]

Example:


ciscoasa(config)# http server enable 444

By default, the port is 443. If you change the port number, be sure to include it in the ASDM access URL. For example, if you change the port number to 444, enter the following URL:

https://10.1.1.1:444

Step 3

(Optional) Set connection and session timeouts.

http server idle-timeoutminutes

http server session-timeoutminutes

  • http server idle-timeout minutes —Set the idle timeout for ASDM connections, from 1-1440 minutes. The default is 20 minutes. The ASA disconnects an ASDM connection that is idle for the set period of time.

  • http server session-timeout minutes —Set the session timeout for ASDM sessions, from 1-1440 minutes. This timeout is disabled by default. The ASA disconnects an ASDM session that exceeds the set period of time.

Example:


ciscoasa(config)# http server idle-timeout 30
ciscoasa(config)# http server session-timeout 120

Examples

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: 


ciscoasa(config)# http server enable
ciscoasa(config)# http 192.168.1.2 255.255.255.255 inside

The following example shows how to allow all users on the 192.168.3.0/24 network to access ASDM on the inside interface: 


ciscoasa(config)# http 192.168.3.0 255.255.255.0 inside

Configure HTTP Redirect for ASDM Access or Clientless SSL VPN

You must use HTTPS to connect to the ASA using ASDM or clientless SSL VPN. For your convenience, you can redirect HTTP management connections to HTTPS. For example, by redirecting HTTP, you can enter either http://10.1.8.4/admin/ or https://10.1.8.4/admin/ and still arrive at the ASDM launch page at the HTTPS address.

You can redirect both IPv4 and IPv6 traffic.

Before you begin

Normally, you do not need an access rule allowing the host IP address. However, for HTTP redirect, you must enable an access rule to allow HTTP; otherwise, the interface cannot listen to the HTTP port.

Procedure

Enable HTTP redirect:

http redirect interface_name [port]

Example:

ciscoasa(config)# http redirect outside 88

The port identifies the port from which the interface redirects HTTP connections. The default is 80.

Configure Management Access Over a VPN Tunnel

If your VPN tunnel terminates on one interface, but you want to manage the ASA by accessing a different interface, you must 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.


Note

For secure SNMP polling over a site-to-site VPN, include the IP address of the outside interface in the crypto map access-list as part of the VPN configuration.

VPN access to an interface other than the one from which you entered the ASA is not supported. For example, if your VPN access is located on the outside interface, you can only initiate a connection directly to the outside interface. You should enable VPN on the directly-accessible interface of the ASA and use name resolution so that you don’t have to remember multiple addresses.

Management access is available via the following VPN tunnel types: IPsec clients, IPsec Site-to-Site, Easy VPN, and the AnyConnect SSL VPN client.

Before you begin

Due to routing considerations with the separate management and data routing tables, the VPN termination interface and the management access interface need to be the same type: both need to be management-only interfaces or regular data interfaces.

Procedure

Specify the name of the management interface that you want to access when entering the ASA from another interface.

management-access management_interface

Bridge group interfaces are not supported.

Example:

ciscoasa(config)# management-access inside

Change the Console Timeout

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.

Procedure

Specify the idle time in minutes (0 through 60) after which the privileged session ends.

console timeout number

Example:

ciscoasa(config)# console timeout 0

The default timeout is 0, which means the session does not time out.

Customize a CLI Prompt

The ability to add information to a prompt allows you to see at-a-glance which ASA you are logged into when you have multiple modules. During a failover, this feature is useful when both ASAs have the same hostname.

In multiple context mode, you can view the extended prompt when you log in to the system execution space or the admin context. Within a non-admin context, you only see the default prompt, which is the hostname and the context name.

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:

cluster-unit

Displays the cluster unit name. Each unit in a cluster can have a unique name.

context

(Multiple mode only) Displays the name of the current context.

domain

Displays the domain name.

hostname

Displays the hostname.

priority

Displays the failover priority as pri (primary) or sec (secondary).

state

Displays the traffic-passing state or role of the unit.

For failover, the following values are displayed for the state keyword:

  • act—Failover is enabled, and the unit is actively passing traffic.

  • stby— Failover is enabled, and the unit is not passing traffic and is in a standby, failed, or other non-active state.

  • actNoFailover—Failover is not enabled, and the unit is actively passing traffic.

  • stbyNoFailover—Failover is not enabled, and the unit is not passing traffic. This might happen when there is an interface failure above the threshold on the standby unit.

For clustering, the values for control and data are shown.

Procedure

Customize the CLI prompt by entering the following command:

prompt {[hostname] [context] [domain] [slot] [state] [priority] [cluster-unit]}

Example:

ciscoasa(config)# prompt hostname context slot state priority
ciscoasa/admin/pri/act(config)#

The order in which you enter the keywords determines the order of the elements in the prompt, which are separated by a slash (/).

Configure a Login Banner

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.

Before you begin

  • From a security perspective, it is important that your banner discourage unauthorized access. Do not use the words “welcome” or “please,” as they appear to invite intruders in. The following banner sets the correct tone for unauthorized access: 

    
You have logged in to a secure device.
If you are not authorized to access this device,
log out immediately or risk possible criminal consequences.

  • After a banner has been added, Telnet or SSH sessions to the ASA may close if:

    • There is not enough system memory available to process the banner message(s).

    • A TCP write error occurs when trying to display banner message(s).

  • See RFC 2196 for guidelines about banner messages.

Procedure

Add a banner to display at one of three times: when a user first connects (message-of-the-day (motd)), when a user logs in (login), and when a user accesses privileged EXEC mode (exec).

banner {exec | login | motd} text

Example:

ciscoasa(config)# banner motd Only authorized access is allowed to $(hostname).

When a user connects to the ASA, the message-of-the-day banner appears first, followed by the login banner and prompts. After the user successfully logs in to the ASA, the exec banner appears.

To add more than one line, precede each line by the banner command.

For the banner text:

  • Spaces are allowed, but tabs cannot be entered using the CLI.

  • There are no limits for banner length other than those for RAM and flash memory.

  • You can dynamically add the hostname or domain name of the ASA by including the strings $(hostname) and $(domain).

  • If you configure a banner in the system configuration, you can use that banner text within a context by using the $(system) string in the context configuration.

Examples

The following examples show how to add a message-of-the-day banner: 

ciscoasa(config)# banner motd Only authorized access is allowed to $(hostname). 

ciscoasa(config)# banner motd Contact me at admin@example.com for any issues.

Set a Management Session Quota

You can establish a maximum number of simultaneous ASDM, SSH, and Telnet sessions that are allowed on the ASA. 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.

Before you begin

In multiple context mode, complete this procedure in the system execution space. To change from the context to the system configuration, enter the changeto system command.

Procedure

Step 1

Enter the following command:

quota management-session number

  • number —Sets the aggregate number of sessions between 0 (unlimited) and 10000.

Example:

Example:


ciscoasa(config)# quota management-session 1000
Step 2

View the current sessions in use.

show quota management-session

Example:


ciscoasa(config)# show quota management-session 

quota management-session limit 3
quota management-session warning level 2
quota management-session level 0
quota management-session high water 2
quota management-session errors 0
quota management-session warnings 0

Configure AAA for System Administrators

This section describes how to configure authentication, management authorization, and command authorization for system administrators.

Configure Management Authentication

Configure authentication for CLI and ASDM access.

About Management Authentication

How you log into the ASA depends on whether or not you enable authentication.

About SSH Authentication

See the following behavior for SSH access with and without authentication:

  • No Authentication—SSH is not available without authentication.

  • Authentication—When you enable SSH authentication, you enter the username and password as defined on the AAA server or local user database. For public key authentication, the ASA only supports the local database. When you configure local SSH authentication, then you also enable password authentication for local users; to prevent password usage, you can create a username without a password. You access user EXEC mode.

About Telnet Authentication

See the following behavior for Telnet access with and without authentication:

  • No Authentication—If you do not enable any authentication for Telnet, you do not enter a username; you enter the login password (set with the password command). There is no default password, so you must set one before you can Telnet to the ASA. You access user EXEC mode.

  • Authentication—If you enable Telnet authentication, you enter the username and password as defined on the AAA server or local user database. You access user EXEC mode.

About ASDM Authentication

See the following behavior for ASDM access with and without authentication. You can also configure certificate authentication, with or without AAA authentication.

  • No Authentication—By default, you can log into ASDM with a blank username and the enable password set by the enable password command, which is blank by default. We suggest that you change the enable password as soon as possible so that it does not remain blank; see Set the Hostname, Domain Name, and the Enable and Telnet Passwords. 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.

  • Certificate Authentication—(Single, routed mode only) You can require that the user have a valid certificate. Enter the certificate username and password, and the ASA validates the certificate against the PKI trustpoint.

  • AAA Authentication—When you enable ASDM (HTTPS) authentication, you enter the username and password as defined on the AAA server or local user database. You can no longer use ASDM with a blank username and the enable password.

  • AAA Authentication plus Certificate Authentication—(Single, routed mode only) When you enable ASDM (HTTPS) authentication, you enter the username and password as defined on the AAA server or local user database. If the username and password are different for the certificate authentication, you are prompted to enter them as well. You can opt to pre-fill the username derived from your certificate.

About Serial Authentication

See the following behavior for access to the serial console port with and without authentication:

  • No Authentication—If you do not enable any authentication for serial access, you do not enter a username or password. You access user EXEC mode.

  • Authentication—If you enable authentication for serial access, you enter the username and password as defined on the AAA server or local user database. You access user EXEC mode.

About Enable Authentication

To enter privileged EXEC mode after logging in, enter the enable command. How this command works depends on whether or not you enable authentication:

  • No Authentication—If you do not configure enable authentication, enter the system enable password when you enter the enable command (set by the enable password command), which is blank by default. However, if you do not use enable authentication, after you enter the enable command, you are no longer logged in as a particular user, which can affect user-based features such as command authorization. To maintain your username, use enable authentication.

  • Authentication—If you configure enable authentication, the ASA prompts you for your username and password as defined on the AAA server or local user database. This feature is particularly useful when you perform command authorization, in which usernames are important in determining the commands that a user can enter.

For enable authentication using the local database, you can use the login command instead of the enable command. The login command maintains the username, but requires no configuration to turn on authentication.


Caution

If you add users to the local database who can gain access to the CLI and whom you do not want to enter privileged EXEC mode, you should configure command authorization. Without command authorization, users can access privileged EXEC mode (and all commands) at the CLI using their own password if their privilege level is 2 or greater (2 is the default). Alternatively, you can discourage the login command by using a AAA server for authentication instead of the local database, or you can set all local users to level 1 so you can control who can use the system enable password to access privileged EXEC mode.

Sessions from the Host Operating System to the ASA

Some platforms support running the ASA as a separate application: for example, the ASASM on the Catalyst 6500, or the ASA on the Firepower 4100/9300. For sessions from the host operating system to the ASA, you can configure serial and Telnet authentication, depending on the type of connection.

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 these sessions. The admin context AAA server or local user database is used in this instance.

Configure Authentication for CLI and ASDM Access

Before you begin

  • Configure Telnet, SSH, or HTTP access.

  • For external authentication, configure a AAA server group. For local authentication, add users to the local database.

  • HTTP management authentication does not support the SDI protocol for a AAA server group.

Procedure

Authenticate users for management access.

aaa authentication {telnet | ssh | http | serial} console {LOCAL | server_group [LOCAL]}

Example:
ciscoasa(config)# aaa authentication ssh console radius_1 LOCAL
ciscoasa(config)# aaa authentication http console radius_1 LOCAL
ciscoasa(config)# aaa authentication serial console LOCAL

The telnet keyword controls Telnet access. For the ASASM, this keyword also affects the session from the switch using the session command. The ssh keyword controls SSH access. The http keyword controls ASDM access. The serial keyword controls console port access. For the ASASM, for example, this keyword affects the virtual console accessed from the switch using the service-module session command.

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 (which 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.

Configure Enable Authentication (Privileged EXEC Mode)

You can authentication users when they enter the enable command.

Before you begin

See About Enable Authentication.

Procedure

Choose one of the following options for authenticating users:

  • To authenticate users with a AAA server or the local database, enter the following command:

    aaa authentication enable console {LOCAL | server_group [LOCAL]}

    Example: 

    
ciscoasa(config)# aaa authentication enable console LOCAL

    The user is prompted for the username and password.

    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 (which 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 of 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.

  • To log in as a user from the local database, enter the following command:

    login

    Example: 

    
ciscoasa# login

    The ASA prompts for your username and password. After you enter your password, the ASA places you in the privilege level that the local database specifies.

    Users can 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.

Configure ASDM Certificate Authentication

You can require certificate authentication, with or without AAA authentication. The ASA validates the certificate against the PKI trustpoint.

Before you begin

This feature is supported in single, routed mode only.

Procedure
Step 1

Enable certificate authentication:

http authentication-certificate interface_name [match certificate_map_name]

Example:

ciscoasa(config)# crypto ca certificate map map1 10
ciscoasa(config-ca-cert-map)# subject-name eq www.example.com
ciscoasa(config)# http authentication-certificate outside match map1

You configure certificate authentication for each interface, so that connections on a trusted/inside interface do not have to provide a certificate. You can use the command multiple times to enable certificate authentication on multiple interfaces.

To require the certificate to match a certificate map, specify the match keyword and the map name. Configure the map using the crypto ca certificate map command.

Step 2

(Optional) Set the attribute used by ASDM to derive the username from the certificate:

http username-from-certificate{primary-attr [secondary-attr] | use-entire-name | use-script} [pre-fill-username]

Example:
ciscoasa(config)# http username-from-certificate CN pre-fill-username

By default, ASDM uses CN OU attributes.

  • The primary-attr argument specifies the attribute to be used to derive the username. The secondary-attr argument specifies an additional attribute to use with the primary attribute to derive the username. You can use the following attributes:

    • C—Country

    • CN—Common Name

    • DNQ—DN qualifier

    • EA—Email Address

    • GENQ—Generational qualifier

    • GN—Given Name

    • I—Initials

    • L—Locality

    • N—Name

    • O—Organization

    • OU—Organizational Unit

    • SER—Serial Number

    • SN—Surname

    • SP—State/Province

    • T—Title

    • UID User ID

    • UPN—User Principal Name

  • The use-entire-name keyword uses the entire DN name.

  • The use-script keyword uses a Lua script generated by ASDM.

  • The pre-fill-username keyword pre-fills the username when prompted for authentication. If the username is different from the one you initially typed in, a new dialog box appears with the username pre-filled. You can then enter the password for authentication.

Control CLI and ASDM Access with Management Authorization

The ASA lets you distinguish between administrative and remote-access users when they authenticate. User role differentiation can prevent remote access VPN and network access users from establishing an administrative connection to the ASA.

Before you begin

RADIUS or LDAP (mapped) users

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.

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.

TACACS+ users

Authorization is requested with “service=shell,” and the server responds with PASS or FAIL.

Local users

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.

Management Authorization Attributes

See the following table for AAA server types and valid values for management authorization. The ASA uses these values to determine the level of management access.

Management Level

RADIUS/LDAP (Mapped) Attributes

TACACS+ Attributes

Local Database Attributes

Full Access—Allows full access to any services specified by the aaa authentication console commands

Service-Type 6 (Administrative), Privilege-Level 1

PASS, privilege level 1

admin

Partial Access—Allows access to the CLI or ASDM when you configure the aaa authentication console commands. However, if you configure enable authentication with the aaa authentication enable console command, then the CLI user cannot access privileged EXEC mode using the enable command.

Service-Type 7 (NAS prompt), Privilege-Level 2 and higher

The Framed (2) and Login (1) service types are treated the same way.

PASS, privilege level 2 and higher

nas-prompt

No Access—Denies management access. The user cannot use any services specified by the aaa authentication console commands(excluding the serial keyword; serial access is allowed). Remote access (IPsec and SSL) users can still authenticate and terminate their remote access sessions. All other service types (Voice, FAX, and so on) are treated the same way.

Service-Type 5 (Outbound)

FAIL

remote-access

Additional Guidelines

  • Serial console access is not included in management authorization.

  • You must also configure AAA authentication for management access to use this feature. See Configure Authentication for CLI and ASDM Access.

  • If you use external authentication, you must pre-configure a AAA server group before you enable this feature.

  • HTTP authorization is supported in single, routed mode only.

Procedure

Step 1

Enable management authorization for Telnet and SSH:

aaa authorization exec {authentication-server | LOCAL} [auto-enable]

The auto-enable keyword lets administrators who have sufficient authorization privileges enter privileged EXEC mode automatically when they log in.

Example:


ciscoasa(config)# aaa authentication ssh console RADIUS
ciscoasa(config)# aaa authorization exec authentication-server auto-enable
Step 2

Enable management authorization for HTTPS (ASDM):

aaa authorization http console {authentication-server | LOCAL}

Example:


ciscoasa(config)# aaa authentication http console RADIUS
ciscoasa(config)# aaa authorization http console authentication-server
Step 3

Examples

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

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

Configure Command Authorization

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:

  • Local privilege levels

  • TACACS+ server privilege levels

About Command Authorization

You can enable command authorization so only authorized users can enter commands.

Supported Command Authorization Methods

You can use one of two command authorization methods:

  • Local privilege levels—Configure the command privilege levels on the ASA. When a local, RADIUS, or LDAP (if you map LDAP attributes to RADIUS attributes) user authenticates for CLI access, the ASA places that user in the privilege level that is defined by the local database, RADIUS, or LDAP server. The user can access commands at the assigned privilege level and below. Note that all users access user EXEC mode when they first log in (commands at level 0 or 1). The user needs to authenticate again with the enable command to access privileged EXEC mode (commands at level 2 or higher), or they can log in with the login command (local database only).


    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.

  • TACACS+ server privilege levels—On the TACACS+ server, configure the commands that a user or group can use after authenticating for CLI access. Every command that a user enters at the CLI is validated with the TACACS+ server.

Security Contexts and Command Authorization

AAA settings are discrete per context, not shared among 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.


Note

The system execution space does not support AAA commands; therefore, command authorization is not available in the system execution space.

Command Privilege Levels

By default, the following commands are assigned to privilege level 0. All other commands are assigned to privilege level 15.

  • show checksum

  • show curpriv

  • enable

  • help

  • show history

  • login

  • logout

  • pager

  • show pager

  • clear pager

  • quit

  • show version

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 cannot enter configuration mode.

Configure Local 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).

Procedure
Step 1

Assign a command to a privilege level.

privilege [show | clear | cmd] level level [mode {enable | cmd}] command command

Example:

ciscoasa(config)# privilege show level 5 command filter

Repeat this command for each command that you want to reassign.

The options in this command are the following:

  • show | clear | cmd —These optional keywords let you set the privilege only for the show, clear, or configure form of the command. The configure form of the command is typically the form that causes a configuration change, either as the unmodified command (without the show or clear prefix) or as the no form. If you do not use one of these keywords, all forms of the command are affected.

  • level level —A level between 0 and 15.

  • mode {enable | configure }—If a command can be entered in user EXEC or privileged EXEC mode as well as configuration mode, and the command performs different actions in each mode, you can set the privilege level for these modes separately:

    • enable —Specifies both user EXEC mode and privileged EXEC mode.

    • configure —Specifies configuration mode, accessed using the configure terminal command.

  • command command —The command you are configuring. You can only configure the privilege level of the main command. For example, you can configure the level of all aaa commands, but not the level of the aaa authentication command and the aaa authorization command separately.

Step 2

(Optional) Enable AAA users for command authorization. Without this command, the ASA only supports privilege levels for local database users and defaults all other types of users to level 15.

aaa authorization exec authentication-server [auto-enable]

Example:

ciscoasa(config)# aaa authorization exec authentication-server

This command also enables management authorization. See Control CLI and ASDM Access with Management Authorization.

Step 3

Enable the use of local command privilege levels:

aaa authorization command LOCAL

Example:

ciscoasa(config)# aaa authorization command LOCAL

When you set command privilege levels, command authorization does not occur unless you configure command authorization with this command.

Examples

The filter command has the following forms:

  • filter (represented by the configure option)

  • show running-config filter

  • clear configure filter

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: 


ciscoasa(config)# privilege show level 5 command filter
ciscoasa(config)# privilege clear level 10 command filter
ciscoasa(config)# privilege cmd level 10 command filter

Alternatively, the following example shows how to set all filter commands to the same level: 


ciscoasa(config)# privilege level 5 command filter

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: 


ciscoasa(config)# privilege cmd level 0 mode enable command enable 
ciscoasa(config)# privilege cmd level 15 mode cmd command enable
ciscoasa(config)# privilege show level 15 mode cmd command enable

The following example shows an additional command, the configure command, which uses the mode keyword: 


ciscoasa(config)# privilege show level 5 mode cmd command configure
ciscoasa(config)# privilege clear level 15 mode cmd command configure 
ciscoasa(config)# privilege cmd level 15 mode cmd command configure
ciscoasa(config)# privilege cmd level 15 mode enable command configure

Note

This last line is for the configure terminal command.

Configure Commands on the TACACS+ Server

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:

  • The ASA sends the commands to be authorized as shell commands, so configure the commands on the TACACS+ server as shell commands.


    Note

    Cisco Secure ACS might include a command type called “pix-shell.” Do not use this type for ASA command authorization.

  • The first word of the command is considered to be the main command. All additional words are considered to be arguments, which need to be preceded by permit or deny.

    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.

  • You can permit all arguments of a command that you do not explicitly deny by checking the Permit Unmatched Args check box.

    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 (see the following figure).

    Figure 1. Permitting All Related Commands

  • For commands that are a single word, you must permit unmatched arguments, even if there are no arguments for the command, for example enable or help (see the following figure).

    Figure 2. Permitting Single Word Commands

  • To disallow some arguments, enter the arguments preceded by deny.

    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 (see the following figure).

    Figure 3. Disallowing Arguments

  • When you abbreviate a command at the command line, the ASA expands the prefix and main command to the full text, but it sends additional arguments to the TACACS+ server as you enter them.

    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 (see the following figure).

    Figure 4. Specifying Abbreviations

  • We recommend that you allow the following basic commands for all users:

    • show checksum

    • show curpriv

    • enable

    • help

    • show history

    • login

    • logout

    • pager

    • show pager

    • clear pager

    • quit

    • show version

Configure TACACS+ Command Authorization

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.

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.

To configure command authorization using a TACACS+ server, perform the following steps:

Procedure

Enter the following command:

aaa authorization command tacacs+_server_group [LOCAL]

Example:

ciscoasa(config)# aaa authorization command tacacs+_server_group [LOCAL]

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 of which method is being used. Be sure to configure users in the local database and command privilege levels.

Configure a Password Policy for Local Database Users

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.

Before you begin

  • Configure AAA authentication for CLI or ASDM access using the local database.

  • Specify usernames in the local database.

Procedure

Step 1

(Optional) Set the interval in days after which passwords expire for remote users.

password-policy lifetime days

Example:


ciscoasa(config)# password-policy lifetime 180
Note 

Users at the console port are never locked out because of password expiration.

Valid values are between 0 and 65536 days. The default value is 0 days, a value indicating that passwords will never expire.

Seven days before the password expires, a warning message appears. After the password expires, system access is denied to remote users. To gain access after expiration, do one of the following:

  • Have another administrator change your password with the username command.

  • Log in to the physical console port to change your password.

Step 2

(Optional) Set the minimum number of characters that you must change between new and old passwords.

password-policy minimum-changes value

Example:


ciscoasa(config)# password-policy minimum-changes 2

Valid values are between 0 and 64 characters. The default value is 0.

Character matching is position independent, meaning that new password characters are considered changed only if they do not appear anywhere in the current password.

Step 3

(Optional) Set the minimum length of passwords.

password-policy minimum-length value

Example:


ciscoasa(config)# password-policy minimum-length 8

Valid values are between 3 and 64 characters. We recommend a minimum password length of 8 characters.

Step 4

(Optional) Set the minimum number of upper case characters that passwords must have.

password-policy minimum-uppercase value

Example:


ciscoasa(config)# password-policy  minimum-uppercase 3

Valid values are between 0 and 64 characters. The default value is 0, which means there is no minimum.

Step 5

(Optional) Set the minimum number of lower case characters that passwords must have.

password-policy minimum-lowercase value

Example:


ciscoasa(config)# password-policy minimum-lowercase 6

Valid values are between 0 and 64 characters. The default value is 0, which means there is no minimum.

Step 6

(Optional) Set the minimum number of numeric characters that passwords must have.

password-policy minimum-numeric value

Example:


ciscoasa(config)# password-policy minimum-numeric 1

Valid values are between 0 and 64 characters. The default value is 0, which means there is no minimum.

Step 7

(Optional) Set the minimum number of special characters that passwords must have.

password-policy minimum-special value

Example:


ciscoasa(config)# password-policy minimum-special 2

Valid values are between 0 and 64 characters. Special characters include the following: !, @, #, $, %, ^, &, *, ‘(‘ and ‘)’. The default value is 0, which means there is no minimum.

Step 8

(Optional) Set whether users must change their password using the change-password command, instead of letting users change their password with the username command.

password-policy authenticate enable

Example:


ciscoasa(config)# password-policy authenticate enable

The default setting is disabled: a user can use either method to change their password.

If you enable this feature and try to change your password with the username command, the following error message appears: 


ERROR: Changing your own password is prohibited

You also cannot delete your own account with the clear configure username command. If you try, the following error message appears: 


ERROR: You cannot delete all usernames because you are not allowed to delete yourself

Change Your Password

If you configure a password lifetime in the password policy, you need to change your password to a new one when the old password expires. This password change method is required if you enable password policy authentication. If password policy authentication is not enabled, then you can use this method, or you can change your user account directly.

To change your username password, perform the following steps:

Procedure

Enter the following command:

change-password [old-password old_password [new-password new_password]]

Example:

ciscoasa# change-password old-password j0hncr1chton new-password a3rynsun

If you do not enter the old and new passwords in the command, the ASA prompts you for input.

Configure Management Access Accounting

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:

Procedure

Step 1

Enter the following command:

aaa accounting {serial | telnet | ssh | enable} console server-tag

Example:


ciscoasa(config)# aaa accounting telnet console group_1

Valid server group protocols are RADIUS and TACACS+.

Step 2

Enable command accounting. Only TACACS+ servers support command accounting.

aaa accounting command [privilege level] server-tag

Example:


ciscoasa(config)# aaa accounting command privilege 15 group_1

The privilege level keyword-argument pair is the minimum privilege level and the server-tag argument is the name of the TACACS+ server group to which the ASA should send command accounting messages.

Recover from a Lockout

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.

The following table lists the common lockout conditions and how you might recover from them.

Table 1. CLI Authentication and Command Authorization Lockout Scenarios

Feature

Lockout Condition

Description

Workaround: Single Mode

Workaround: Multiple Mode

Local CLI authentication

No users have been configured in the local database.

If you have no users in the local database, you cannot log in, and you cannot add any users.

Log in and reset the passwords and aaa commands.

Session into the ASA from the switch. From the system execution space, you can change to the context and add a user.

TACACS+ command authorization

TACACS+ CLI authentication

RADIUS CLI authentication

The server is down or unreachable and you do not have the fallback method configured.

If the server is unreachable, then you cannot log in or enter any commands.

  1. Log in and reset the passwords and AAA commands.

  2. Configure the local database as a fallback method so you do not get locked out when the server is down.

  1. If the server is unreachable because the network configuration is incorrect on the ASA, session into the ASA from the switch. From the system execution space, you can change to the context and reconfigure your network settings.

  2. Configure the local database as a fallback method so that you do not get locked out when the server is down.

TACACS+ command authorization

You are logged in as a user without enough privileges or as a user that does not exist.

You enable command authorization, but then find that the user cannot enter any more commands.

Fix the TACACS+ server user account.

If you do not have access to the TACACS+ server and you need to configure the ASA immediately, then log into the maintenance partition and reset the passwords and aaa commands.

Session into the ASA from the switch. From the system execution space, you can change to the context and complete the configuration changes. You can also disable command authorization until you fix the TACACS+ configuration.

Local command authorization

You are logged in as a user without enough privileges.

You enable command authorization, but then find that the user cannot enter any more commands.

Log in and reset the passwords and aaa commands.

Session into the ASA from the switch. From the system execution space, you can change to the context and change the user level.

Monitoring Device Access

See the following commands for monitoring device access:

  • show running-config all privilege all

    This command shows privilege levels for all commands.

    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: 

    
ciscoasa(config)# show running-config all  privilege all
privilege show level 15 command aaa
privilege clear level 15 command aaa
privilege configure level 15 command aaa
privilege show level 15 command aaa-server
privilege clear level 15 command aaa-server
privilege configure level 15 command aaa-server
privilege show level 15 command access-group
privilege clear level 15 command access-group
privilege configure level 15 command access-group
privilege show level 15 command access-list
privilege clear level 15 command access-list
privilege configure level 15 command access-list
privilege show level 15 command activation-key
privilege configure level 15 command activation-key
...

  • show running-config privilege level level

    This command shows commands for a specific privilege level. The level argument is an integer between 0 and 15.

    The following example shows the command assignments for privilege level 10: 

    
ciscoasa(config)# show running-config all privilege level 10 
privilege show level 10 command aaa

  • show running-config privilege command command

    This command shows the privilege level of a specific command.

    The following example shows the command assignments for the access-list command: 

    
ciscoasa(config)# show running-config all privilege command access-list
privilege show level 15 command access-list
privilege clear level 15 command access-list
privilege configure level 15 command access-list

  • show curpriv

    This command shows the currently logged-in user.

    The following is sample output from the show curpriv command: 

    
ciscoasa# show curpriv
Username: admin
Current privilege level: 15
Current Mode/s: P_PRIV

    The following table describes the show curpriv command output.

    Table 2. show curpriv Command Output Description

    Field

    Description

    Username

    Username. If you are logged in as the default user, the name is enable_1 (user EXEC) or enable_15 (privileged EXEC).

    Current privilege level

    Levels range from 0 to 15. Unless you configure local command authorization and assign commands to intermediate privilege levels, levels 0 and 15 are the only levels that are used.

    Current Modes

    The available access modes are the following:

    • P_UNPR—User EXEC mode (levels 0 and 1)

    • P_PRIV—Privileged EXEC mode (levels 2 to 15)

    • P_CONF—Configuration mode

  • show quota management-session

    This command shows the current sessions in use.

    The following is sample output from the show quota management-session command: 

    
ciscoasa(config)# show quota management-session 

quota management-session limit 3
quota management-session warning level 2
quota management-session level 0
quota management-session high water 2
quota management-session errors 0
quota management-session warnings 0

History for Management Access

Table 3. History for Management Access

Feature Name

Platform Releases

Description

ASA SSL Server mode matching for ASDM

9.6(2)

For an ASDM user who authenticates with a certificate, you can now require the certificate to match a certificate map.

We modified the following command: http authentication-certificate match

SSH public key authentication improvements

9.6(2)

In earlier releases, you could enable SSH public key authentication (ssh authentication ) without also enabling AAA SSH authentication with the Local user database (aaa authentication ssh console LOCAL ). The configuration is now fixed so that you must explicitly enable AAA SSH authentication. To disallow users from using a password instead of the private key, you can now create a username without any password defined.

We modified the following commands: ssh authentication, username

ASDM management authorization

9.4(1)

You can now configure management authorization separately for HTTP access vs. Telnet and SSH access.

We introduced the following command: aaa authorization http console

ASDM username from certificate configuration

9.4(1)

When you enable ASDM certificate authentication (http authentication-certificate), you can configure how ASDM extracts the username from the certificate; you can also enable pre-filling the username at the login prompt.

We introduced the following command: http username-from-certificate

Improved one-time password authentication

9.2(1)

Administrators who have sufficient authorization privileges may enter privileged EXEC mode by entering their authentication credentials once. The auto-enable option was added to the aaa authorization exec command.

We modified the following command: aaa authorization exec.

HTTP redirect support for IPV6

9.1(7)/9.6(1)

When you enable HTTP redirect to HTTPS for ASDM access or clientless SSL VPN, you can now redirect traffic sent an to IPv6 address.

We added functionality to the following command: http redirect

Configurable SSH encryption and integrity ciphers

9.1(7)/9.4(3)/9.5(3)/9.6(1)

Users can select cipher modes when doing SSH encryption management and can configure HMAC and encryption for varying key exchange algorithms. You might want to change the ciphers to be more or less strict, depending on your application. Note that the performance of secure copy depends partly on the encryption cipher used. By default, the ASA negotiates one of the following algorithms in order: 3des-cbc aes128-cbc aes192-cbc aes256-cbc aes128-ctr aes192-ctr aes256-ctr. If the first algorithm proposed (3des-cbc) is chosen, then the performance is much slower than a more efficient algorithm such as aes128-cbc. To change the proposed ciphers, use ssh cipher encryption custom aes128-cbc , for example.

We introduced the following commands: ssh cipher encryption, ssh cipher integrity.

AES-CTR encryption for SSH

9.1(2)

The SSH server implementation in the ASA now supports AES-CTR mode encryption.

Improved SSH rekey interval

9.1(2)

An SSH connection is rekeyed after 60 minutes of connection time or 1 GB of data traffic.

We introduced the following command: show ssh sessions detail.

For the ASASM in multiple context mode, support for Telnet and virtual console authentication from the switch.

8.5(1)

Although connecting to the ASASM from the switch in multiple context mode connects to the system execution space, you can configure authentication in the admin context to govern those connections.

Support for administrator password policy when using the local database

8.4(4.1), 9.1(2)

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.

We introduced the following commands: change-password, password-policy lifetime, password-policy minimum changes, password-policy minimum-length, password-policy minimum-lowercase, password-policy minimum-uppercase, password-policy minimum-numeric, password-policy minimum-special, password-policy authenticate enable, clear configure password-policy, show running-config password-policy.

Support for SSH public key authentication

8.4(4.1), 9.1(2)

You can enable public key authentication for SSH connections to the ASA on a per-user basis. You can specify a public key file (PKF) formatted key or a Base64 key. The PKF key can be up to 4096 bits. Use PKF format for keys that are too large to for the ASA support of the Base64 format (up to 2048 bits).

We introduced the following commands: ssh authentication.

PKF key format support is only in 9.1(2) and later.

Support for Diffie-Hellman Group 14 for the SSH Key Exchange

8.4(4.1), 9.1(2)

Support for Diffie-Hellman Group 14 for SSH Key Exchange was added. Formerly, only Group 1 was supported.

We introduced the following command: ssh key-exchange.

Support for a maximum number of management sessions

8.4(4.1), 9.1(2)

You can set the maximum number of simultaneous ASDM, SSH, and Telnet sessions.

We introduced the following commands: quota management-session, show running-config quota management-session, show quota management-session.

Increased SSH security; the SSH default username is no longer supported.

8.4(2)

Starting in 8.4(2), you can no longer connect to the ASA using SSH with the pix or asa username and the login password. To use SSH, you must configure AAA authentication using the aaa authentication ssh console LOCAL command (CLI) or Configuration > Device Management > Users/AAA > AAA Access > Authentication (ASDM); then define a local user by entering the username command (CLI) or choosing Configuration > Device Management > Users/AAA > User Accounts (ASDM). If you want to use a AAA server for authentication instead of the local database, we recommend also configuring local authentication as a backup method.

Management Access

7.0(1)

We introduced this feature.

We introduced the following commands:

show running-config all privilege all, show running-config privilege level, show running-config privilege command, telnet, telnet timeout, ssh, ssh timeout, http, http server enable, asdm image disk, banner, console timeout, icmp, ipv6 icmp, management access, aaa authentication console, aaa authentication enable console, aaa authentication telnet | ssh console, service-type, login, privilege, aaa authentication exec authentication-server, aaa authentication command LOCAL, aaa accounting serial | telnet | ssh | enable console, show curpriv, aaa accounting command privilege.