List of important port numbers

15 --- Netstat

21 --- FTP

23 --- Telnet

25 --- SMTP

42 --- WINS

53 --- DNS

67 --- Bootp

68 --- DHCP

80 --- HTTP

88 --- Kerberos

101 --- HOSTNAME

110 --- POP3

119 --- NNTP

123 --- NTP (Network time protocol)

139 --- NetBIOS

161 --- SNMP

180 --- RIS

389 --- LDAP (Lightweight Directory Access Protocol)

443 --- HTTPS (HTTP over SSL/TLS)

520 --- RIP

79 --- FINGER

37 --- Time

3389 --- Terminal services

443 --- SSL (https) (http protocol over TLS/SSL)

220 --- IMAP3

3268 --- AD Global Catalog

3269 --- AD Global Catalog over SSL

500 --- Internet Key Exchange, IKE (IPSec) (UDP 500)