Disabling Unneeded Features and Services on Cisco Internet Gateway Routers

The focus of this document is on closing down services and features as part of the hardening of the router. The classical idea behind this is that it is best practice to close down not only some services known as dangerous, but also all services and features that are not needed. There seems to be a consensus that especially on border routers, which are not protected by a firewall, this has high value. Originally I was convinced that it would be easy to build a list of services to close down. While concentrating on this during my research it turned out to be a major challenge.