Cisco - Basic Router Security

Here are some of the configutaions I'd like to share to secure a Cisco router. There are default programs running on your Cisco router that attackers used to compromise the router.

A. Disable the TCP and UDP 

Router(config)#no service tcp-small-servers

Router(config)#no service udp-small-servers

B. Disable Finger

Router(config)#no ip finger

Router(config)#no service finger

C. Don't use SNMP if possible. Don't use HTTP server if not necessary.

Router(config)#no ip http server

D. Disable Bootp Server

Router(config)#no ip bootp server

E. Disable Auto-Loading

Router(config)#no boot network

Router(config)#no service config

F. Disable IP Source Routing

Router(config)#no ip source-route

G. Disable Proxy ARP. It could be used to bypass security perimeter.

Router(config)#int fa0/0

Router(config-if)#no ip proxy-arp

H. If you are using a Classful Routing, disable the IP Classless Routing.

Router(config)#no ip classless

I. Disable IP Unreachables, Redirects, Mask Reply

Router(config)#int fa0/0

Router(config-if)#no ip unreachable

Router(config-if)#no ip redirect

Router(config-if)#no ip mask-reply