Checking common port numbers on Cisco IOS

While memorizing a bunch of port numbers definitely helps you impress the ladies, not everyone has that ability. Fortunately, you can check common port numbers right on the Cisco IOS command line.

Router> enable
Router# conf t
Router# access-list 100 permit tcp any any eq ?

This will result in the following table:

 <0-65535>    Port number
bgp          Border Gateway Protocol (179)
chargen      Character generator (19)
cmd          Remote commands (rcmd, 514)
daytime      Daytime (13)
discard      Discard (9)
domain       Domain Name Service (53)
echo         Echo (7)
exec         Exec (rsh, 512)
finger       Finger (79)
ftp          File Transfer Protocol (21)
ftp-data     FTP data connections (used infrequently, 20)
gopher       Gopher (70)
hostname     NIC hostname server (101)
ident        Ident Protocol (113)
irc          Internet Relay Chat (194)
klogin       Kerberos login (543)
kshell       Kerberos shell (544)
login        Login (rlogin, 513)
lpd          Printer service (515)
nntp         Network News Transport Protocol (119)
pim-auto-rp  PIM Auto-RP (496)
pop2         Post Office Protocol v2 (109)
pop3         Post Office Protocol v3 (110)
smtp         Simple Mail Transport Protocol (25)
sunrpc       Sun Remote Procedure Call (111)
syslog       Syslog (514)
tacacs       TAC Access Control System (49)
talk         Talk (517)
telnet       Telnet (23)
time         Time (37)
uucp         Unix-to-Unix Copy Program (540)
whois        Nicname (43)
www          World Wide Web (HTTP, 80)