Cisco IOS Security Configuration Guide: Securing User Services, Release 12.4

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Book Title

Cisco IOS Security Configuration Guide: Securing User Services, Release 12.4

Chapter Title

Attribute Screening for Access Requests

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Updated:
December 28, 2007

Chapter: Attribute Screening for Access Requests


Attribute Screening for Access Requests

First Published: November 19, 2003
Last Updated: August 6, 2009

The Attribute Screening for Access Requests feature allows you to configure your network access server (NAS) to filter attributes in outbound Access Requests to the RADIUS server for purposes of authentication or authorization.

Finding Feature Information

Your software release may not support all the features documented in this module. 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 Attribute Screening for Access Requests" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://tools.cisco.com/ITDIT/CFN/jsp/index.jsp. An account on Cisco.com is not required.

Contents

•Prerequisites for Attribute Screening for Access Requests

•Restrictions for Attribute Screening for Access Requests

•Information About Attribute Screening for Access Requests

•How to Configure Attribute Screening for Access Requests

•Configuration Examples for Attribute Filtering for Access Requests

•Additional References

•Feature Information for Attribute Screening for Access Requests

Prerequisites for Attribute Screening for Access Requests

•You must be familiar with configuring attribute lists.

Restrictions for Attribute Screening for Access Requests

•Attributes 1 (Username), 2 (User-Password), and 3 (Chap-Password) cannot be filtered.

Information About Attribute Screening for Access Requests

To configure the Attribute Screening for Access Requests feature, you should understand the following concept:

•Configuring an NAS to Filter Attributes in Outbound Access Requests

Configuring an NAS to Filter Attributes in Outbound Access Requests

The Attribute Screening for Access Requests feature allows you to configure your NAS to filter attributes in outbound Access Requests to the RADIUS server for purposes of authentication or authorization. The filters can be configured on the NAS, or they can be downloaded via downloadable vendor-specific attributes (VSAs) from the authentication, authorization, and accounting (AAA) server.

The following are some examples of the downloadable VSAs: 

Cisco:Cisco-Avpair="ppp-authen-type=chap"

Cisco:Cisco-Avpair="ppp-authen-list=group 1"

Cisco:Cisco-Avpair="ppp-author-list=group 1"

Cisco:Cisco-Avpair="vpdn:tunnel-id=B53"

Cisco:Cisco-Avpair="vpdn:ip-addresses=10.0.58.35"

Note You must be aware of which attributes you want to filter. Filtering certain key attributes can result in authentication failure (for example, attribute 60 should not be filtered).

How to Configure Attribute Screening for Access Requests

This section contains the following procedures:

•Configuring Attribute Screening for Access Requests

•Configuring a Router to Support Downloadable Filters

•Monitoring and Maintaining Attribute Filtering for Access Requests

Configuring Attribute Screening for Access Requests

To configure the attribute screening for access requests, perform the following steps.

SUMMARY STEPS

1. enable

2. configure terminal

3. radius-server attribute list listname

4. attribute value1 [value2 [value3...]]

5. aaa group server radius group-name

6. authorization [request | reply] [accept | reject] listname

or

accounting [request | reply] [accept | reject] listname

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 

radius-server attribute list listname

Example:

Router (config)# radius-server attribute list attrlist

Defines an attribute list.

Step 4 

attribute value1 [value2[value3...]]

Example:

Router (config)# attribute 6-10, 12

Adds attributes to an accept or reject list.

Step 5 

aaa group server radius group-name

Example:

Router (config)# aaa group server radius rad1

Applies the attribute list to the AAA server group and enters server-group configuration mode.

Step 6 

authorization [request | reply][accept | reject] listname


or

accounting [request | reply] [accept | reject] listname

Example:

Router (config-sg-radius)# authorization request accept attrlist


or

Example:

Router (config-sg-radius)# accounting request accept attrlist

Filters attributes in outbound Access Requests to the RADIUS server for purposes of authentication or authorization.

•The request keyword defines filters for outgoing authorization Access Requests.

•The reply keyword defines filters for incoming authorization Accept and Reject packets and for outgoing accounting requests.

Configuring a Router to Support Downloadable Filters

Perform this task to configure your router to support downloadable filters.

SUMMARY STEPS

1. enable

2. configure terminal

3. aaa authorization template

4. aaa authorization network default group radius

5. radius-server attribute list list-name

6. attribute value1 [value2 [value3...]]

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 authorization template

Example:

Router (config)# aaa authorization template

Enables usage of a local or remote customer template on the basis of Virtual Private Network (VPN) routing and forwarding (VRF).

Step 4 

aaa authorization network default group radius

Example:

Router (config)# aaa authorization network default group radius

Sets parameters that restrict user access to a network.

Step 5 

radius-server attribute list list-name

Example:

Router (config)# radius-server attribute list attlist

Defines an accept or reject list name.

Step 6 

attribute value1 [value2 [value3...]]

Example:

Router (config)# attribute 10-14, 24

Adds attributes to an accept or reject list.

Troubleshooting Tips

If attribute filtering is not working, ensure that the attribute list is properly defined.

Monitoring and Maintaining Attribute Filtering for Access Requests

To monitor and maintain attribute filtering, you can use the debug radius command.

SUMMARY STEPS

1. enable

2. debug radius

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

debug radius

Example:

Router# debug radius

Displays information associated with RADIUS, including filtering information.

Configuration Examples for Attribute Filtering for
Access Requests

This section provides the following configuration examples:

•Attribute Filtering for Access Requests: Example

•Attribute Filtering User Profile: Example

•debug radius Command: Example

Attribute Filtering for Access Requests: Example

The following example shows that the attributes 30-31 that are defined in "all-attr" will be rejected in all outbound Access Request messages: 

aaa group server radius ras

 server 172.19.192.238 auth-port 1745 acct-port 1746

 authorization request reject all-attr

!

.

.

.

radius-server attribute list all-attr

 attribute 30-31

!

.

.

.

Attribute Filtering User Profile: Example

The following is a sample user profile after attribute filtering has been configured for Access Requests: 

cisco.com Password = "cisco"

Service-Type = Framed,

Framed-Protocol = PPP,

Cisco:Cisco-Avpair = :1:"rad-serv=172.19.192.87 key rad123",

Cisco:Cisco-Avpair = :1:"rad-serv-filter=authorization request reject range1",

Cisco:Cisco-Avpair = :1:"rad-serv-filter=accounting request reject range1",

Cisco:Cisco-Avpair = "ppp-authen-type=chap"

Cisco:Cisco-Avpair = "ppp-authen-list=group 1",

Cisco:Cisco-Avpair = "ppp-author-list=group 1",

Cisco:Cisco-Avpair = "ppp-acct-list=start-stop group 1",

Cisco:Cisco-Avpair = "vpdn:tunnel-id=B53",

Cisco:Cisco-Avpair = "vpdn:tunnel-type=l2tp",

Cisco:Cisco-Avpair = "vpdn:ip-addresses=10.0.58.35",

Cisco:Cisco-Avpair = "vpdn:l2tp-tunnel-password=cisco"



user2@cisco.com

Service-Type = Outbound,

Cisco:Cisco-Avpair = "vpdn:tunnel-id=B53",

Cisco:Cisco-Avpair = "vpdn:tunnel-type=l2tp",

Cisco:Cisco-Avpair = "vpdn:ip-addresses=10.0.58.35",

Cisco:Cisco-Avpair = "vpdn:l2tp-tunnel-password=cisco"

When a session for user2@cisco.com "comes up" at the Layer 2 Tunneling Protocol (L2TP) Network Server (LNS)—as is shown above—because the aaa authorization template command has been configured, a RADIUS request is sent to the server for Cisco.com. The server then sends an Access Accept message if authentication is successful, along with the VSAs that are configured as part of the Cisco.com profile. If filters are configured as part of the Cisco.com profile, these filters will be parsed and applied to the RADIUS requests for user2@cisco.com.

In the above profile example, filter range1 has been applied to the authorization and accounting requests.

debug radius Command: Example

If the attribute you are trying to filter is rejected, you will see an debug radius output statement similar to the following: 

RADIUS: attribute 31 rejected

If you try to filter an attribute that cannot be filtered, you will see an output statement similar to the following: 

RADIUS: attribute 1 cannot be rejected

Additional References

The following sections provide references related to Attribute Filtering for Access Requests.

Related Documents

Related Topic
Document Title

Configuring RADIUS

"Configuring RADIUS" feature document.

Security commands

Cisco IOS Security Command Reference

RADIUS attribute lists

"RADIUS Attribute Screening" feature document.


Standards

Standards
Title

None

—


MIBs

MIBs
MIBs Link

None

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFCs
Title

None

—


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport


Feature Information for Attribute Screening for Access Requests

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS 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 software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.

Table 1 Feature Information for Attribute Screening for Access Requests 

Feature Name
Releases
Feature Information

Attribute Screening for Access Requests

12.3(3)B
12.3(7)T
12.2(28)SB
12.2(33)SRC

The Attribute Screening for Access Requests feature allows a network access server (NAS) to be configured to filter attributes in outbound Access Requests to the RADIUS server for purposes of authentication or authorization.

In 12.3(3)B, this feature was introduced.

This feature was integrated into Cisco IOS Release 12.3(7)T

This feature was integrated into Cisco IOS Release 12.2(28)SB.

This feature was integrated into Cisco IOS Release 12.2(33)SRC.

The following commands were introduced or modified by this feature: authorization (server-group).


Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

© 2003-2009 Cisco Systems, Inc. All rights reserved.

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