Cisco Cisco IOS Software Release 12.2(33)SRE

Prior to the introduction of the HSRP MD5 Authentication feature, Hot Standby Router Protocol (HSRP) 
authenticated protocol packets with a simple plain text string. The HSRP MD5 Authentication feature is 
an enhancement to generate an MD5 digest for the HSRP portion of the multicast HSRP protocol packet. 
This feature provides added security and protects against the threat from HSRP-spoofing software. 

Configuration information is included in the “Configuring HSRP” chapter in the

 Cisco IOS IP 

, Release 12.4T

at the following URL:

Command reference information is included in the 

, Release 12.2SR, at the following URL:

The following commands are new or modified for this feature:

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

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