Broken Protocol Example RFC 2082: RIP-2 MD5 Authentication There are a number of other problems with this RFC, some of which are documented in J. Etienne's "Flaws in RIPv2 packet's authentication" (http://off.net/~jme/ietf/draft-etienne-ripv2-auth-flaws-00.txt) There is also update: RFC4822 (January 2007) "RIPv2 Cryptographic Authentication" Basically a FIPS update to SHA1-HMAC Solves some of the problems (doesn't use time anymore) Other things remain broken