Common Network Ports Cheat Sheet

Understanding ports and their associated protocols is vital for smooth communication and robust security. Ports are essentially endpoints where communication passes through, and they work with two primary protocols: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). Below is a cheat sheet of commonly used ports, indicating whether they utilize TCP, UDP, or both.

Well-Known Ports (0-1023)

HTTP (Port 80)

• Protocol: TCP
• Description: Hypertext Transfer Protocol for transmitting web pages.
• Use Case: Web browsing and accessing websites.

HTTPS (Port 443)

• Protocol: TCP
• Description: Secure version of HTTP with encryption over TLS/SSL.
• Use Case: Secure web browsing and transactions.

FTP (Port 21)

• Protocol: TCP
• Description: File Transfer Protocol for transferring files.
• Use Case: Uploading and downloading files from a server.

SSH (Port 22)

• Protocol: TCP
• Description: Secure Shell for encrypted command-line access.
• Use Case: Remote management of servers and devices.

Telnet (Port 23)

• Protocol: TCP
• Description: Text-based protocol for remote command-line interface.
• Use Case: Remote network device management (not recommended due to lack of security).

SMTP (Port 25)

• Protocol: TCP
• Description: Simple Mail Transfer Protocol for sending emails.
• Use Case: Email server communications.

DNS (Port 53)

• Protocol: Both TCP and UDP
• Description: Domain Name System, UDP for queries and TCP for zone transfers.
• Use Case: Resolving domain names to IP addresses.

DHCP (Ports 67/68)

• Protocol: UDP
• Description: Dynamic Host Configuration Protocol assigns IP addresses.
• Use Case: Network configuration automation.

POP3 (Port 110)

• Protocol: TCP
• Description: Post Office Protocol version 3 for retrieving emails.
• Use Case: Email retrieval from a server.

IMAP (Port 143)

• Protocol: TCP
• Description: Internet Message Access Protocol for email access.
• Use Case: Email access and synchronization.

Registered Ports (1024-49151)

MySQL (Port 3306)

• Protocol: TCP
• Description: Database management system.
• Use Case: Database access for applications.

PostgreSQL (Port 5432)

• Protocol: TCP
• Description: Advanced open-source relational database system.
• Use Case: Applications requiring robust database management.

RDP (Port 3389)

• Protocol: TCP
• Description: Remote Desktop Protocol for Windows desktops.
• Use Case: Remote desktop sharing and control.

SMB (Port 445)

• Protocol: TCP
• Description: Server Message Block protocol for file sharing.
• Use Case: File and printer sharing on local networks.

LDAP (Port 389)

• Protocol: TCP and UDP
• Description: Lightweight Directory Access Protocol for directory services.
• Use Case: Managing organizational databases, such as user information.

SIP (Port 5060/5061)

• Protocol: Both TCP and UDP
• Description: Session Initiation Protocol for VoIP.
• Use Case: Voice over IP and video calling.

SNMP (Port 161)

• Protocol: UDP
• Description: Simple Network Management Protocol for managing devices.
• Use Case: Monitoring network devices.

Dynamic and Private Ports (49152-65535)

These ports are often used for ephemeral communication, typically assigned temporarily for client-server communication using either TCP or UDP, depending on the application’s needs.

Conclusion

Understanding the interplay between ports and protocols like TCP and UDP is essential for network security and operation. This cheat sheet serves as a quick reference, but remember network security practices involve ensuring these ports are used securely.