Well-known Ports

The following is a list of well-known ports often used:

• 20 // FTP data channel
• 21 // FTP control channel
• 23 // Telnet
• 25 // SMTP
• 53 // Connection-oriented DNS (resolution is on UDP 53); zone transfer
• 69 // tftp.exe
• 80
• 88 // Kerberos
• 88 //Internet Key Exchange (IKE)
• 110 // POP3 (Mail)
• 123 // Network Time Protocol
• 135 // DCE Endpoints
• 137 // NETBIOS Name Service
• 138 // NETBIOS Datagram Service
• 139 // SMB; NetBIOS session
• 161 // SNMP
• 389 // LDAP
• 443
• 445 // Common Internet File System / native SMB on Windows 2000 and higher
• 500 // isakmp
• 636 // LDAP over SSL
• 1025 // Network blackjack
• 1433 // SQL Server listens on TCP port 1433
• 1434 // SQL Server uses UDP port 1434 for client-server negotiation
• 1723 // PPTP
• 1801 // MSMQ
• 2393 //MS OLAP 1
• 2394 // MS OLAP 2
• 2725 // MS OLAP PTP2
• 3268 // MS Global Catalog
• 3269 // MS Global Catalog with LDAP/SSL
• 3389 // RDP uses the TCP 3389 port
• 3693 // IIS Administration Web Site–port; often blocked, I guess

I'll update the lists.