SSH Protocol v.2 packet format Multiple MAC algorithms supported hmac-md5, hmac-sha1, truncated MACs, none Payload may optionally be compressed prior to MAC Packets are optionally encrypted with a symmetric cipher 3-des-cbc (MUST) blowfish-cbc (RECOMMENDED) twofish-cbc, aes-cbc, serpent-cbc (OPTIONAL) arcfour, idea-cbc, cast128-cbc (OPTIONAL)