Encrypted Vendor-Specific Attributes
First Published: February 25, 2002
Last Updated: July 7, 2009
The Encrypted Vendor-Specific Attributes feature provides users with a way to centrally manage filters at a RADIUS server and supports the following types of string vendor-specific attributes (VSAs):
•Tagged String VSA (similar to Cisco VSA type 1 (Cisco:AVPair (1)) except that this new VSA is tagged)
•Encrypted String VSA (similar to Cisco VSA type 1 except that this new VSA is encrypted)
•Tagged and Encrypted String VSA (similar to Cisco VSA type 1 except that this new VSA is tagged and encrypted)
Cisco:AVPairs specify additional authentication and authorization information in the form an Attribute-Value Pair (AVPair) string. When Internet Engineering Task Force (IETF) RADIUS attribute 26 (Vendor-Specific) is transmitted with a vendor-Id number of "9" and a vendor-type value of "1" (which means that it is a Cisco AVPair), the RADIUS user profile format for a Cisco AVPair looks as follows: Cisco:AVPair = "protocol:attribute=value".
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 Encrypted Vendor-Specific Attributes" 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.
•Prerequisites for Encrypted Vendor-Specific Attributes
•Information About Encrypted Vendor-Specific Attributes
•How to Verify Encrypted Vendor-Specific Attributes
•Configuration Examples for Encrypted Vendor-Specific Attributes
•Feature Information for Encrypted Vendor-Specific Attributes
Prerequisites for Encrypted Vendor-Specific Attributes
Before the RADIUS server can accept tagged and encrypted VSAs, you must configure your server for AAA authentication and authorization and to accept PPP calls.
For information on performing these tasks, refer to the chapter "PPP Configuration" in the Cisco IOS Dial Technologies Configuration Guide, Release 12.4 and the chapters "Configuring Authentication" and "Configuring Authorization" in the Cisco IOS Security Configuration Guide, Release 12.4.
Information About Encrypted Vendor-Specific Attributes
The following sections describe packet encryption formats for the different VSAs:
•Tagged String VSA
•Encrypted String VSA
•Tagged and Encrypted String VSA
Tagged String VSA
Figure 1 displays the packet format for the Tagged String VSA:
Figure 1 Tagged String VSA Format
To retrieve the correct value, the Tag field must be parsed correctly. The value for this field can range only from 0x01 through 0x1F. If the value is not within the specified range, the RADIUS server ignores the value and considers the Tag field to be a part of the Attribute String field.
Encrypted String VSA
Figure 2 displays the packet format for the Encrypted String VSA:
Figure 2 Encrypted String VSA Format
The Salt field ensures the uniqueness of the encryption key that is used to encrypt each instance of the VSA. The first and most significant bit of the Salt field must be set to 1.
Note Vendor-type (36) indicates that the attribute is an encrypted string VSA.
Tagged and Encrypted String VSA
Figure 3 displays the packet formats for each of the newly supported VSAs:
Figure 3 Tagged and Encrypted String VSA Format
This VSA is similar to encrypted string VSAs except this VSA has an additional Tag field. If the Tag field is not within the valid range (0x01 through 0x1F), it is considered to be part of the Salt field.
How to Verify Encrypted Vendor-Specific Attributes
The Encrypted Vendor-Specific Attributes feature requires no configuration. To verify that RADIUS-tagged and encrypted VSAs are being sent from the RADIUS server, use the following command in privileged EXEC mode:
Router# debug radius
Displays information associated with RADIUS. The output of this command shows whether tagged and encrypted VSAs are being sent from the RADIUS server.
Configuration Examples for Encrypted Vendor-Specific Attributes
This section provides the following configuration examples:
•NAS Configuration Example
•RADIUS User Profile with a Tagged and Encrypted VSA Example
NAS Configuration Example
The following example shows how to configure a network access server (NAS) with a basic configuration using tagged and encrypted VSAs. (This example assumes that the configuration required to make PPP calls is already enabled.)
aaa authentication ppp default group radius
aaa authorization network default group radius
radius-server host 10.2.2.2 auth-port 1645 acct-port 1646
RADIUS User Profile with a Tagged and Encrypted VSA Example
The following is an example of user profile on a RADIUS server that supports tagged and encrypted string VSAs:
mascot Password = "password1"
Service-Type = NAS-Prompt,
Cisco:Cisco-Enc = "ip:route=10.0.0.0 255.0.0.0"
Cisco.attr Cisco-Enc 36 tag-encstr(*,*)
The following sections provide references related to the Encrypted Vendor-Specific Attributes.
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
Remote Authentication Dial In User Service (RADIUS)
RADIUS Attributes for Tunnel Protocol Support
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Feature Information for Encrypted Vendor-Specific Attributes
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 Encrypted Vendor-Specific Attributes
Encrypted Vendor-Specific Attributes
Cisco IOS XE Release 2.3
The Encrypted Vendor-Specific Attributes feature provides users with a way to centrally manage filters at a RADIUS server and supports the Tagged String, Encrypted String, and Tagged and Encrypted String vendor-specific attributes (VSAs).
This feature was introduced in Cisco IOS Release 12.2(8)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.
In Cisco IOS XE Release 2.3, this feature was implemented on the Cisco ASR 1000 series routers.
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