port-map feature

Ever forget what port number maps to what service? A router running Adv IP Services, Adv Security, or Adv Enterprise Services will tell you all the common ones using the show ip port-map command, which is part of the IOS firewall feature set:

Router#sh ip port-map
Default mapping: snmp udp port 161 system defined
Default mapping: echo tcp port 7 system defined
Default mapping: echo udp port 7 system defined
Default mapping: telnet tcp port 23 system defined
Default mapping: wins tcp port 1512 system defined
Default mapping: n2h2server tcp port 9285 system defined
Default mapping: n2h2server udp port 9285 system defined
Default mapping: nntp tcp port 119 system defined
Default mapping: pptp tcp port 1723 system defined
Default mapping: rtsp tcp port 554,8554 system defined
Default mapping: bootpc udp port 68 system defined
Default mapping: gdoi udp port 848 system defined
Default mapping: tacacs udp port 49 system defined

[output truncated]

You can, of course, filter for stuff you find interesting:

Router#sh ip port-map | i 110
Default mapping: pop3 tcp port 110 system defined