FTP (File Transfer Protocol) - A protocol used for transferring files between computers on a network. Port 21 is used for the control channel, and port 20 is used for the data channel.
Port 22
SSH (Secure Shell) - A protocol used for secure remote login and command execution.
Port 23
Telnet - A protocol used for remote login to a computer or network device over a network.
Port 25
SMTP (Simple Mail Transfer Protocol) - A protocol used for sending email messages between servers or from a mail client to a mail server.
Port 53
DNS (Domain Name System) - A protocol used for translating domain names into IP addresses and vice versa.
Port 80
HTTP (Hypertext Transfer Protocol) - A protocol used for transmitting web pages and other web content over the internet.
Port 110
POP3 (Post Office Protocol version 3) - A protocol used for retrieving email messages from a mail server.
Port 135-139
NetBIOS (Network Basic Input/Output System) - A protocol used for file sharing and printer sharing on a local network.
Port 143
IMAP (Internet Message Access Protocol) - A protocol used for accessing email messages on a mail server.
Port 161-162
SNMP (Simple Network Management Protocol) - A protocol used for managing and monitoring network devices.
Port 389
LDAP (Lightweight Directory Access Protocol) - A protocol used for accessing and maintaining distributed directory information services.
Port 443
HTTPS (Hypertext Transfer Protocol Secure) - A protocol used for transmitting web pages and other web content over the internet using a secure encrypted connection.
Port 3389
RDP (Remote Desktop Protocol) - A protocol used for remote desktop access to a computer over a network.
Port 548
AFP (Apple Filing Protocol) - A protocol used for file sharing between Mac computers.
Port 445
SMB (Server Message Block) - A protocol used for file sharing, printer sharing, and other communication between computers on a network.
Port 427
SLP (Service Location Protocol) - A protocol used for discovering network services on a local network.