18 Essential Network Ports: A Must-Know Guide for Secure and Efficient IT Operations

FTP (File Transfer Protocol) – TCP/21
Purpose: Used for transferring files between clients and servers.

SSH (Secure Shell) – TCP/22
Purpose: Provides a secure channel for remote login and command execution.

Telnet – TCP/23
Purpose: Offers unencrypted, text-based remote login.

SMTP (Simple Mail Transfer Protocol) – TCP/25
Purpose: Responsible for sending email from clients to mail servers and between mail servers.

DNS (Domain Name System) – UDP/TCP/53
Purpose: Translates human-friendly domain names into IP addresses (and vice versa).

DHCP Server – UDP/67
Purpose: Assigns IP addresses and network configuration parameters to DHCP clients.

DHCP Client – UDP/68
Purpose: Used by client machines to receive IP address leases and network settings from the DHCP server.

HTTP (Hypertext Transfer Protocol) – TCP/80
Purpose: Primary protocol for transferring web pages and related data.

POP3 (Post Office Protocol v3) – TCP/110
Purpose: Retrieves emails from a remote mail server to a local client.

NTP (Network Time Protocol) – UDP/123
Purpose: Synchronizes the clocks of computers over a network.

NetBIOS – TCP/139
Purpose: Allows applications on different computers to communicate within a LAN. Often used by Windows file and print sharing in older setups.

IMAP (Internet Message Access Protocol) – Typically TCP/143
Purpose: Retrieves and manages email on a mail server, allowing multiple clients to access mailboxes simultaneously.

HTTPS (Secure HTTP) – TCP/443
Purpose: Secured version of HTTP, encrypting data in transit with SSL/TLS.

SMB (Server Message Block) – TCP/445
Purpose: Provides file and printer sharing services primarily on Windows networks.

Oracle Database – TCP/1521
Purpose: Default listener port for Oracle Database connections.

MySQL – TCP/3306
Purpose: Default port for MySQL database communication.

RDP (Remote Desktop Protocol) – TCP/3389
Purpose: Remote desktop access to Windows-based systems.

PostgreSQL – TCP/5432
Purpose: Default port for PostgreSQL database connections.