AAA Authorization and Authentication Cache

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.

Prerequisites 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.

Information About Implementing Authorization and Authentication Profile Caching

Network Performance Optimization Using 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.

Authorization and Authentication Profile Caching as a Failover Mechanism

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.

Method Lists in Authorization and Authentication Profile Caching

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 database), none (do nothing), RADIUS server group, or TACACS+ server group. Typically, more than one method can be configured into a method list. Software uses the first listed method to authenticate users. If that method fails to respond, the 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.

Authorization and Authentication Profile Caching Guidelines

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.

General Configuration Procedure for Implementing Authorization and Authentication Profile 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.

  1. Update existing server groups to reference newly defined cache groups.

  2. Update authentication or authorization method lists to use the cached information to optimize network performance or provide a failover mechanism.

How to Implement Authorization and Authentication Profile Caching

Creating Cache Profile Groups and Defining Caching Rules

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.

SUMMARY STEPS

  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

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Router> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Router# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Router(config)# aaa new-model

Enables the AAA access control model.

Step 4

aaa cache profile group-name

Example:


Router(config)# aaa cache profile networkusers@companyname

Defines an authentication and authorization cache profile server group and enters profile map configuration mode.

Step 5

profile name [no-auth ]

Example:


Router(config-profile-map# profile networkuser1 no-auth

Creates an individual authentication and authorization cache profile based on a username match.

  • The name argument must be an exact match to a username being queried by an authentication or authorization service request.

  • Use the no-auth keyword to bypass authentication for this user.

Step 6

Repeat Step 5 for each username you want to add to the profile group in Step 4.

--

Step 7

regexp matchexpression {any | only } [no-auth ]

Example:


Router(config-profile-map)# regexp .*@example.com any no-auth

(Optional) Creates an entry in a cache profile group that matches based on a regular expression.

  • If you use the any keyword, all unique usernames matching the regular expression are saved.

  • If you use the only keyword, only one profile entry is cached for all usernames matching the regular expression.

  • Use the no-auth keyword to bypass authentication for this user or set of users.

  • Because the number of entries in a regular expression cache profile group could be in the thousands, and validating each request against a regular expression can be time consuming, we do not recommend using regular expression entries in cache profile groups.

Step 8

Repeat Step 7 for each regular expression you want to add to the cache profile group defined in Step 4.

--

Step 9

all [no-auth ]

Example:


Router(config-profile-map)# all no-auth

(Optional) Specifies that all authentication and authorization requests are cached.

  • Use the all command for specific service authorization requests, but it should be avoided when dealing with authentication requests.

Step 10

end

Example:


Router(config-profile-map)# end

Returns to privileged EXEC mode.

Step 11

show aaa cache group name

Example:


Router# show aaa cache group networkusers@companyname

(Optional) Displays all cache entries for a specified group.

Step 12

clear aaa cache group name {profile name | all }

Example:


Router# clear aaa cache group networkusers@companyname profile networkuser1

(Optional) Clears an individual entry or all entries in the cache.

Step 13

debug aaa cache group

Example:


Router# debug aaa cache group

(Optional) Displays debug information about cached entries.

Defining RADIUS and TACACS Server Groups That Use Cache Profile Group Information

Perform this task to define how RADIUS and TACACS+ server groups use the information stored in each cache profile group.

Before you begin

RADIUS and TACACS+ server groups must be created.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa new-model
  4. aaa group server radius group-name oraaa group server tacacs+ group-name
  5. cache authorization profile name
  6. cache authentication profile name
  7. cache expiry hours {enforce failover }
  8. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Router> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Router# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Router(config)# aaa new-model

Enables the AAA access control model.

Step 4

aaa group server radius group-name oraaa group server tacacs+ group-name

Example:


Router(config)# aaa group server radius networkusers@companyname

Enters RADIUS server group configuration mode.

  • To enter TACACS+ server group configuration mode, use the aaa group server tacacs+ group-name command.

Step 5

cache authorization profile name

Example:


Router(config-sg-radius)# cache authorization profile networkusers@companyname

Activates the authorization caching rules in the profile networkusers for this RADIUS or TACACS+ server group.

  • The name argument in this command is a AAA cache profile group name.

Step 6

cache authentication profile name

Example:


Router(config-sq-radius)# cache authentication profile networkusers@companyname

Activates the authentication caching rules in the profile networkusers for this RADIUS or TACACS+ server group.

Step 7

cache expiry hours {enforce failover }

Example:


Router(config-sq-radius)# cache expiry 240 failover

(Optional) Sets the amount of time before a cache profile entry expires (becomes stale).

  • Use the enforce keyword to specify that once a cache profile entry expires it is not used again.

  • Use the failover keyword to specify that an expired cache profile entry can be used if all other methods to authenticate and authorize the user fail.

Step 8

end

Example:


Router(config-sg-radius)# end

Returns to privileged EXEC mode.

Updating Authorization and Authentication Method Lists to Specify How Cache Information is Used

Perform this task to update authorization and authentication method lists to use the authorization and authentication cache information.

Before you begin

Method lists must already be defined.

SUMMARY STEPS

  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

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Router> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Router# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Router(config)# aaa new-model

Enables the AAA access control model.

Step 4

aaa authorization {network | exec | commands level | reverse-access | configuration } {default | list-name } [method1 [method2... ]]

Example:


Router(config)# aaa authorization network default cache networkusers@companyname group networkusers@companyname

Enables AAA authorization and creates method lists, which define the authorization methods used when a user accesses a specified function.

Step 5

aaa authentication ppp {default | list-name } method1 [method2... ]

Example:


Router(config)# aaa authentication ppp default cache networkusers@companyname group networkusers@companyname

Specifies one or more authentication methods for use on serial interfaces that are running PPP.

Step 6

aaa authentication login {default | list-name } method1 [method2... ]

Example:


Router(config)# aaa authentication login default cache adminusers group adminusers

Sets the authentication at login.

Step 7

end

Example:


Router(config)# end

Returns to privileged EXEC mode.

Configuration Examples for Implementing Authorization and Authentication Profile Caching

Implementing Authorization and Authentication Profile Caching for Network Optimization 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

Implementing Authorization and Authentication Profile Caching as a Failover Mechanism Example

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

Additional References for RADIUS Change of Authorization

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Command List, All Releases

Security commands

Configuring AAA

Authentication, Authorization, and Accounting Configuration Guide

Standards and RFCs

Standard/RFC

Title

RFC 2903

Generic AAA Architecture

RFC 5176

Dynamic Authorization Extensions to Remote Authentication Dial In User Service(RADIUS)

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for Implementing Authorization and Authentication Profile Caching

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1. Feature Information for Implementing Authentication and Authorization Profile Caching

Feature Name

Release

Feature Information

AAA Authorization and Authentication Cache

Cisco IOS XE Release 2.3

This feature optimizes network performance and provides a failover mechanism in the event a network RADIUS or TACACS+ server becomes unavailable for any reason.

In Cisco IOS XE Release 2.3, this feature was introduced on the Cisco ASR 1000 Series Aggregation Services Routers.

The following commands were introduced or modified: aaa authentication login , aaa authentication ppp , aaa authorization , aaa cache profile , all (profile map configuration) , cache authentication profile (server group configuration) , cache authorization profile (server group configuration) , cache expiry (server group configuration) , clear aaa cache group , debug aaa cache group , profile (profile map configuration) , regexp (profile map configuration) , show aaa cache group .