RANCID
http://tuxtraining.com/2008/10/07/how-to-install-and-configure-rancid-with-postfix
http://www.shrubbery.net/pipermail/rancid-discuss/2007-July/002318.html
http://www.networkcomputing.com/wan-optimization-and-application-acceleration/rancid-tool-keeps-config-files-clean.php?p=4
http://homepage.mac.com/duling/halfdozen/RANCID-Howto.html
http://www.debian-administration.org/article/Network_Administration__Installation_of_Tacacs_Rancid_Cvsweb
http://www.shrubbery.net/rancid/man/router.db.5.html
http://www.shrubbery.net/rancid/