Configuring AAA
This chapter describes how to configure authentication, authorization, and accounting (AAA) and includes the following sections:
•
Information About AAA
•
Prerequisites for AAA
•
AAA Guidelines and Limitations
•
Configuring AAA
•
Additional References
•
Feature History for AAA
Information About AAA
This section includes the following topics:
•
AAA Security Services
•
AAA Server Groups
AAA Security Services
Based on a user ID and password combination, AAA is used to authenticate and authorize users. A key secures communication with AAA servers.
In many circumstances, AAA uses protocols such as RADIUS or TACACS+, to administer its security functions. If your router or access server is acting as a network access server, AAA is the means through which you establish communication between your network access server and your RADIUS or TACACS+, security server.
Although AAA is the primary (and recommended) method for access control, additional features for simple access control are available outside the scope of AAA, such as local username authentication, line password authentication, and enable password authentication. However, these features do not provide the same degree of access control that is possible by using AAA.
Separate AAA configurations are made for the following services:
•
User Telnet or Secure Shell (SSH) login authentication
•
Console login authentication
•
User management session accounting
Table 4-1 shows the related CLI command for configuring an AAA service.
.
Table 4-1 AAA Service Configuration Commands
AAA Service Configuration Option
|
|
Telnet or SSH login |
aaa authentication login default |
Console login |
aaa authentication login console |
AAA secures the following:
•
Authentication
•
Authorization
•
Accounting
Authentication
Authentication identifies users with a login and password, messaging, and encryption.
Authentication is accomplished as follows:
|
|
Local database |
Authenticates the following with a local lookup database of user names or passwords. • Console login authentication • User login authentication • User management session accounting |
Remote RADIUS or TACACS+ server |
Authenticates the following using a remote server lookup database of user names and passwords. • Console login authentication • User login authentication • User management session accounting |
None |
Authenticates the following with only a username. • Console login authentication • User login authentication • User management session accounting |
Figure 4-1 Authenticating User Log In
Authorization
Authorization restricts the actions that a user is allowed to perform.
Accounting
Accounting tracks and maintains a log of every SVS management session. You can use this information to generate reports for troubleshooting and auditing purposes. You can store accounting logs locally or send them to remote AAA servers.
AAA Server Groups
Remote AAA server groups can provide fail-over in case one remote AAA server fails to respond. If the first server in the group fails, the next server in the group is tried until a server responds. Multiple server groups can provide fail-over for each other in this same way.
If all remote server groups fail, the local database is used for authentication.
Prerequisites for AAA
Authentication using remote AAA servers requires that the following be in place:
•
At least one TACACS+ server is IP reachable
See the "Configuring a TACACS+ Server Host" section on page 6-11.
•
The SVS is configured as an AAA server client.
•
A shared secret key is configured on the SVS and the remote AAA server.
See the "Configuring Shared Keys" procedure on page 6-9.
AAA Guidelines and Limitations
The Cisco Nexus 1000Vdoes not support user names made up of all numeric characters and does not create local user names made up of all numeric characters. If a username made up of all numeric characters exists on an AAA server and is entered during login, the SVS does authenticate the user.
Configuring AAA
This section includes the following topics:
•
Configuring a Login Authentication Method
•
Enabling Login Authentication Failure Messages
•
Verifying AAA Configuration
•
Verifying AAA Configuration
•
Example AAA Configuration
•
Default Settings
Use the following flow chart to configure AAA.
Flow Chart: Configuring AAA
Configuring a Login Authentication Method
Use this procedure to configure the login authentication method.
BEFORE YOU BEGIN
Before beginning this procedure, you must know or do the following:
•
You are logged in to the CLI in EXEC mode.
•
If authentication is to be done with TACACS+ server group(s), you have already added the group(s). For more information, see Configuring a TACACS+ Server Group, page 6-12.
SUMMARY STEPS
1.
config t
2.
aaa authentication login {console | default} {group group-list [none] | local | none}
3.
exit
4.
show aaa authentication
5.
copy running-config start-config
DETAILED STEPS
|
|
|
Step 1 |
config t
Example: n1000v# config t n1000v(config)# |
Places you into the CLI Global Configuration mode. |
Step 2 |
aaa authentication login {console | default} {group group-list [none]| local | none}
Example: n1000v(config)# aaa authentication login console group tacgroup |
Configures the console or default login authentication method. • group: Authentication is done by server group(s). – group-list: List server group names separated by spaces; or none for no authentication. • local: The local database is used for authentication. Note Local is the default and is used when no methods are configured or when all the configured methods fail to respond. • none: Authentication is done by username. |
Step 3 |
exit
Example: n1000v(config)# exit n1000v# |
Exits the CLI Global Configuration mode and returns you to EXEC mode. |
Step 4 |
show aaa authentication
Example: n1000v# show aaa authentication default: group tacgroup console: group tacgroup n1000v# |
(Optional) Displays the configured login authentication method. |
Step 5 |
copy running-config startup-config
Example: n1000v# copy running-config startup-config |
(Optional) Copies the running configuration to the startup configuration. |
Enabling Login Authentication Failure Messages
Use this procedure to enable the login authentication failure message to displays if the remote AAA servers do not respond.
BEFORE YOU BEGIN
Before beginning this procedure, you must know or do the following:
•
You are logged in to the CLI in EXEC mode.
•
The following is the Login Authentication Failure message:
Remote AAA servers unreachable; local authentication done.
Remote AAA servers unreachable; local authentication failed.
SUMMARY STEPS
1.
config t
2.
aaa authentication login error-enable
3.
exit
4.
show aaa authentication login error-enable
5.
copy running-config start-config
DETAILED STEPS
|
|
|
Step 1 |
config t
Example: n1000v# config t n1000v(config)# |
Places you in CLI Global Configuration mode. |
Step 2 |
aaa authentication login error-enable
Example: n1000v(config)# aaa authentication login error-enable n1000v(config)# |
Enables login authentication failure messages. The default is disabled. |
Step 3 |
exit
Example: n1000v(config)# exit n1000v# |
Exits CLI Global Configuration mode and returns you to EXEC mode. |
Step 4 |
show aaa authentication login error-enable
Example:
n1000v# show aaa authentication login error-enable enabled n1000v# |
(Optional) Displays the login failure message configuration. |
Step 5 |
copy running-config startup-config
Example: n1000v# copy running-config startup-config |
(Optional) Copies the running configuration to the startup configuration. |
Verifying AAA Configuration
To display AAA configuration information, perform one of the following tasks:
|
|
show aaa authentication [login {error-enable | mschap}] |
Displays AAA authentication information. See Example 4-1 |
show aaa groups |
Displays the AAA server group configuration. |
show running-config aaa [all] |
Displays the AAA configuration in the running configuration. See Example 4-2 |
show startup-config aaa |
Displays the AAA configuration in the startup configuration. See Example 4-3 |
Example 4-1 show aaa authentication
n1000v# show aaa authentication login error-enable
Example 4-2 show running config aaa
n1000v# show running-config aaa all
aaa authentication login default local
aaa accounting default local
no aaa authentication login error-enable
no aaa authentication login mschap enable
no radius-server directed-request
no snmp-server enable traps aaa server-state-change
no tacacs-server directed-request
Example 4-3 show startup-config aaa
n1000v# show startup-config aaa
Example AAA Configuration
The following is an AAA configuration example:
aaa authentication login default group tacacs
aaa authentication login console group tacacs
Default Settings
The following table lists the AAA defaults.
|
|
Console authentication method |
local |
Default authentication method |
local |
Login authentication failure messages |
Disabled |
Additional References
For additional information related to implementing AAA, see the following sections:
•
Related Documents
•
Standards
Related Documents
|
|
System Management |
Cisco Nexus 1000V System Management Configuration Guide, Release 4.0(4)SV1(2) |
CLI |
Cisco Nexus 1000V Getting Started Guide, Release 4.0(4)SV1(2) |
TACACS+ Security protocol |
Chapter 6, "Configuring TACACS+" |
Standards
|
|
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
— |
Feature History for AAA
This section provides the AAA release history.
|
|
|
AAA |
4.0 |
This feature was introduced. |