Cisco Systems 3750E manual Understanding Kerberos

Chapter 9 Configuring Switch-Based Authentication

Controlling Switch Access with Kerberos

You must obtain authorization to use this feature and to download the cryptographic software files from Cisco.com.For more information, see the release notes for this release.

These sections contain this information:

•Understanding Kerberos, page 9-32

•Kerberos Operation, page 9-34

•Configuring Kerberos, page 9-35

For Kerberos configuration examples, see the “Kerberos Configuration Examples” section in the “Security Server Protocols” chapter of the Cisco IOS Security Configuration Guide, Release 12.2, at this URL:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter0918 6a00800ca7ad.html

Note For complete syntax and usage information for the commands used in this section, see the “Kerberos Commands” section in the “Security Server Protocols” chapter of the Cisco IOS Security Command Reference, Release 12.2, at this URL:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_reference_chapter0918 6a00800ca7b9.html

Note In the Kerberos configuration examples and in the Cisco IOS Security Command Reference, Release 12.2, the trusted third party can be a Catalyst 3750-E or 3560-E switch that supports Kerberos, that is configured as a network security server, and that can authenticate users by using the Kerberos protocol.

Understanding Kerberos

Kerberos is a secret-key network authentication protocol, which was developed at the Massachusetts Institute of Technology (MIT). It uses the Data Encryption Standard (DES) cryptographic algorithm for encryption and authentication and authenticates requests for network resources. Kerberos uses the concept of a trusted third party to perform secure verification of users and services. This trusted third party is called the key distribution center (KDC).

Kerberos verifies that users are who they claim to be and the network services that they use are what the services claim to be. To do this, a KDC or trusted Kerberos server issues tickets to users. These tickets, which have a limited lifespan, are stored in user credential caches. The Kerberos server uses the tickets instead of usernames and passwords to authenticate users and network services.

Note A Kerberos server can be a Catalyst 3750-E or 3560-E switch that is configured as a network security server and that can authenticate users by using the Kerberos protocol.

The Kerberos credential scheme uses a process called single logon. This process authenticates a user once and then allows secure authentication (without encrypting another password) wherever that user credential is accepted.

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

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