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The AAA Authorization and Authentication Cache feature allows you to cache authorization and authentication responses for a configured set of users or service profiles, providing performance improvements and an additional level of network reliability because user and service profiles that are returned from authorization and authentication responses can be queried from multiple sources and need not depend solely on an offload server. This feature also provides a failover mechanism so that if a network RADIUS or TACACS+ server is unable to provide authorization and authentication responses network users and administrators can still access the network.
For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Implementing Authorization and Authentication Profile Caching" section.
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•Prerequisites for Implementing Authorization and Authentication Profile Caching
•Information About Implementing Authorization and Authentication Profile Caching
•How to Implement Authorization and Authentication Profile Caching
•Configuration Examples for Implementing Authorization and Authentication Profile Caching
•Feature Information for Implementing Authorization and Authentication Profile Caching
The following prerequisites apply to implementing authorization and authentication profile caching:
•Understand how you would want to implement profile caching, that is, are profiles being cached to improve network performance or as a failover mechanism if your network authentication and authorization (RADIUS and TACACS+) servers become unavailable.
•RADIUS and TACACS+ server groups must already be configured.
To implement authorization and authentication profile caching, you should understand the following concepts:
•Network Performance Optimization Using Authorization and Authentication Profile Caching
•Authorization and Authentication Profile Caching as a Failover Mechanism
•Method Lists in Authorization and Authentication Profile Caching
•Authorization and Authentication Profile Caching Guidelines
•General Configuration Procedure for Implementing Authorization and Authentication Profile Caching
RADIUS and TACACS+ clients run on Cisco routers and send authentication requests to a central RADIUS or TACACS+ server that contains all user authentication and network service access information. The router is required to communicate with an offload RADIUS or TACACS+ server to authenticate a given call and then apply a policy or service to that call. Unlike authentication, authorization, and accounting (AAA) accounting, AAA authentication and authorization is a blocking procedure, which means the call setup may not proceed while the call is being authenticated and authorized. Thus, the time required to process the call setup is directly impacted by the time required to process such an authentication or authorization request from the router to the offload RADIUS or TACACS+ server, and back again. Any communication problems in the transmission, offload server utilization, and numerous other factors cause significant degradation in a router's call setup performance due simply to the AAA authentication and authorization step. The problem is further highlighted when multiple AAA authentications and authorizations are needed for a single call or session.
A solution to this problem is to minimize the impact of such authentication requests by caching the authentication and authorization responses for given users on the router, thereby removing the need to send the requests to an offload server again and again. This profile caching adds significant performance improvements to call setup times. Profile caching also provides an additional level of network reliability because user and service profiles that are returned from authentication and authorization responses can be queried from multiple sources and need not depend solely on an offload server.
To take advantage of this performance optimization, you need to configure the authentication method list so that the AAA cache profile is queried first when a user attempts to authenticate to the router. See the "Method Lists in Authorization and Authentication Profile Caching" section for more information.
If, for whatever reason, RADIUS or TACACS+ servers are unable to provide authentication and authorization responses, network users and administrators can be locked out of the network. The profile caching feature allows usernames to be authorized without having to complete the authentication phase. For example, a user by the name of user100@example.com with a password secretpassword1 could be stored in a profile cache using the regular expression ".*@example.com". Another user by the name of user101@example.com with a password of secretpassword2 could also be stored using the same regular expression, and so on. Because the number of users in the ".*@example.com" profile could number in the thousands, it is not feasible to authenticate each user with their personal password. Therefore authentication is disabled and each user simply accesses authorization profiles from a common Access Response stored in cache.
The same reasoning applies in cases where higher end security mechanisms such as Challenge Handshake Authentication Protocol (CHAP), Microsoft Challenge Handshake Authentication Protocol (MS-CHAP), or Extensible Authentication Protocol (EAP), which all use an encrypted password between the client and AAA offload server, are used. To allow these unique, secure username and password profiles to retrieve their authorization profiles, authentication is bypassed.
To take advantage of this failover capability, you need to configure the authentication and authorization method list so that the cache server group is queried last when a user attempts to authenticate to the router. See the "Method Lists in Authorization and Authentication Profile Caching" section for more information.
A method list is a sequential list describing the authentication methods to be queried in order to authenticate a user. We support methods such as local (use the local Cisco IOS XE database), none (do nothing), RADIUS server group, or TACACS+ server group. Typically, more than one method can be configured into a method list. Cisco IOS XE software uses the first listed method to authenticate users. If that method fails to respond, the Cisco IOS XE software selects the next authentication method listed in the method list. This process continues until there is successful communication with a listed authentication method, or until all methods defined in the method list are exhausted.
To optimize network performance or provide failover capability using the profile caching feature you simply change the order of the authentication and authorization methods in the method list. To optimize network performance, make sure the cache server group appears first in the method list. For failover capability, the cache server group should appear last in the method list.
Because the number of usernames and profiles that can request to be authenticated or authorized at a given router on a given point of presence (POP) can be quite extensive, it would not be feasible to cache all of them. Therefore, only usernames and profiles that are commonly used or that share a common authentication and authorization response should be configured to use caching. Commonly used usernames such as aolip and aolnet, which are used for America Online (AOL) calls, or preauthentication dialed number identification service (DNIS) numbers used to connect Public Switched Telephone Network (PSTN) calls to a network attached storage device, along with domain-based service profiles, are all examples of usernames and profiles that can benefit from authentication and authorization caching.
To implement authorization and authentication profile caching, you would complete the following procedure:
1. Create cache profile groups and define the rules for what information is cached in each group.
Entries that match based on exact username, regular expressions, or specify that all authentication and authorization requests can be cached.
2. Update existing server groups to reference newly defined cache groups.
3. Update authentication or authorization method lists to use the cached information to optimize network performance or provide a failover mechanism.
This section contains the following tasks:
•Creating Cache Profile Groups and Defining Caching Rules (required)
•Defining RADIUS and TACACS+ Server Groups That Use Cache Profile Group Information (required)
•Updating Authorization and Authentication Method Lists to Specify How Cache Information is Used (required)
Perform this task to create a cache profile group, define the rules for what information is cached in that group, and verify and manage cache profile entries.
1. enable
2. configure terminal
3. aaa new-model
4. aaa cache profile group-name
5. profile name [no-auth]
6. Repeat Step 5 for each username you want to add to the profile group in Step 4.
7. regexp matchexpression {any | only} [no-auth]
8. Repeat Step 7 for each regular expression you want to add to the cache profile group defined in
Step 4.
9. all [no-auth]
10. end
11. show aaa cache group name
12. clear aaa cache group name {profile name | all}
13. debug aaa cache group
Perform this task to define how RADIUS and TACACS+ server groups use the information stored in each cache profile group.
RADIUS and TACACS+ server groups must be created.
1. enable
2. configure terminal
3. aaa new-model
4. aaa group server radius group-name
or
aaa group server tacacs+ group-name
5. cache authorization profile name
6. cache authentication profile name
7. cache expiry hours [enforce | failover]
8. end
Perform this task to update authorization and authentication method lists to use the authorization and authentication cache information.
Method lists must already be defined.
1. enable
2. configure terminal
3. aaa new-model
4. aaa authorization {network | exec | commands level | reverse-access | configuration} {default | list-name} [method1 [method2...]]
5. aaa authentication ppp {default | list-name} method1 [method2...]
6. aaa authentication login {default | list-name} method1 [method2...]
7. end
This section contains the following examples:
•Implementing Authorization and Authentication Profile Caching for Network Optimization: Example
•Implementing Authorization and Authentication Profile Caching as a Failover Mechanism: Example
The following configuration example shows how to:
•Define a cache profile group adminusers that contains all administrator names on the network and sets it as the default list that is used for all login and exec sessions.
•Activate the new caching rules for a RADIUS server group.
•Add the new cache profile group in the authentication and authorization method list and change the method order so that the cache profile group is queried first.
configure terminal
aaa new-model
! Define aaa cache profile groups and the rules for what information is saved to cache.
aaa cache profile admin_users
profile adminuser1
profile adminuser2
profile adminuser3
profile adminuser4
profile adminuser5
exit
! Define server groups that use the cache information in each profile group.
aaa group server radius admins@companyname.com
cache authorization profile admin_users
cache authentication profile admin_users
! Update authentication and authorization method lists to specify how profile groups and server groups are used.
aaa authentication login default cache admins@companyname.com group admins@companyname.com
aaa authorization exec default cache admins@companyname.com group admins@companyname.com
end
The following configuration example shows how to:
•Create a cache profile group admin_users that contains all of the administrators on the network so that if the RADIUS or TACACS+ server should become unavailable the administrators can still access the network.
•Create a cache profile group abc_users that contains all of the ABC company users on the network so that if the RADIUS or TACACS+ server should become unavailable these users will be authorized to use the network.
•Activate the new caching rules for each profile group on a RADIUS server.
•Add the new cache profile group in the authentication and authorization method list and change the method order so that the cache profile group is queried last.
configure terminal
aaa new-model
! Define aaa cache profile groups and the rules for what information is saved to cache.
aaa cache profile admin_users
profile admin1
profile admin2
profile admin3
exit
aaa cache profile abcusers
profile .*@example.com only no-auth
exit
! Define server groups that use the cache information in each cache profile group.
aaa group server tacacs+ admins@companyname.com
server 10.1.1.1
server 10.20.1.1
cache authentication profile admin_users
cache authorization profile admin_users
exit
aaa group server radius abcusers@example.com
server 172.16.1.1
server 172.20.1.1
cache authentication profile abcusers
cache authorization profile abcusers
exit
! Update authentication and authorization method lists to specify how cache is used.
aaa authentication login default cache admins@companyname.com group admins@companyname.com
aaa authorization exec default cache admins@companyname.com group admins@companyname.com
aaa authentication ppp default group abcusers@example.com cache abcusers@example.com
aaa authorization network default group abcusers@example.com cache abcusers@example.com
end
The following sections provide references related to implementing authentication and authorization profile caching.
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Authentication configuring tasks |
"Configuring Authentication" chapter in the Cisco IOS XE Security Configuration Guide: Securing User Services, Release 2 |
Authorization configuration tasks |
"Configuring Authorization" chapter in the Cisco IOS XE Security Configuration Guide: Securing User Services, Release 2 |
RADIUS configuration tasks |
"Configuring RADIUS" chapter in the Cisco IOS XE Security Configuration Guide: Securing User Services, Release 2 |
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No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
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No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
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Table 1 lists the release history for this feature.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://tools.cisco.com/ITDIT/CFN/jsp/index.jsp. An account on Cisco.com is not required.
Note Table 1 lists only the Cisco IOS XE software release that introduced support for a given feature in a given Cisco IOS XE software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.