rancid -- Really Awesome New Cisco confIg Differ

This is a popular ISP toolkit, based on expect and shell scripts,
for managing router configurations.
Rancid monitors a router's (or device's) configuration, including
software and hardware (cards, serial numbers, etc), using CVS.
Rancid currently supports Cisco routers, Juniper routers, Catalyst
switches, Foundry switches, Redback NASs, and ADC EZT3 muxes.
This is the core package.