RANCID, "Really Awesome New Cisco config Differ”, is a tool to automatically retrieve configuration files from a router and store it in a CVS environment. With CVS changes over time in these configurations can be tracked. There are various front ends to watch these changes, e.g.
"cvsweb" or "viewcvs".

Rancid is a program written in perl, which uses external programs to connect to a router (telnet, ssh, rsh, expect) and to store the retrieved data (CVS). When these external programs are IPv6-ready, it is easy to use rancid in an IPv6 environment.