Cisco ASA 5505 - Manual (Page 755)

37-15
Cisco ASA 5500 Series Configuration Guide using the CLI
Chapter 37 Configuring Management Access
Configuring AAA for System Administrators
• About Preserving User Credentials, page 37-15
• Security Contexts and Command Authorization, page 37-16
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 (see the
“Configuring Local Command Authorization” section on page 37-23 ). (See the command
reference for more information about the enable command.)
• 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.
About Preserving User Credentials
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 local server is configured to authenticate user access.
• Privilege level 15 command access is configured to require a password.
• The user account is configured for serial-only authorization (no access to console or ASDM).
• The user account is configured for privilege level 15 command access.
The following table shows how credentials are used in this case by the ASA.
Credentials required
Username and
Password
Authentication
Serial
Authorization
Privileged Mode
Command
Authorization Privileged
Mode Exit
Authorization
Username Yes No No Yes