Common Port / Protocol Mappings

Port 20 (TCP)

FTP Data Transfer - the actual file data channel

Port 21 (TCP)

FTP Control (establishes the FTP connection/commands)

Port 22 (TCP)

SSH - encrypted remote login and command execution

Port 23 (TCP)

Telnet - unencrypted remote login service; sends plaintext msgs (insecure).

Port 25 (TCP)

SMTP - for email routing between servers

Port 53 (TCP)

DNS zone transfers - maps domain names to IPs

Port 53 (UDP)

DNS queries - maps domain names to IPs

Port 80 (TCP)

HTTP (Hypertext Transfer Protocol), unencrypted web traffic

Port 110 (TCP)

POP3 - used by email clients to retrieve email from a server

Port 119 (TCP)

NNTP (NW News Transfer Protocol), used for Usenet newsgroup article transfer

Port 123 (UDP)

NTP - synchronises clocks between NWed devices

Port 143 (TCP)

IMAP (Internet Message Access Protocol), management and retrieval of digital mail from a server

Port 161 (UDP)

SNMP - to monitor and manage NW devices remotely

Port 194 (TCP)

IRC - real-time text messaging and chat protocol

Port 443 (TCP)

HTTPS (HTTP Secure), encrypted web traffic using TLS/SSL

UDP is only used on

Ports 53, 123, 161