What Is Port Number Reference?

A free online port number reference guide covering the most commonly used TCP and UDP ports. Browse well-known ports (0-1023), registered ports (1024-49151), and dynamic/private ports (49152-65535). Search by port number, service name, or keyword. Each entry shows the port number, protocol (TCP/UDP), standardized service name, and a clear description of its purpose. Categories include web (HTTP/HTTPS), email (SMTP/IMAP/POP3), database (MySQL/PostgreSQL/MongoDB/Redis), remote access (SSH/RDP/VNC), security (VPN/TLS), and development (Docker/Kubernetes/Git). Includes a port range reference section for quick orientation.

TCP and UDP port numbers are the addressing mechanism that allows multiple network services to run on a single IP address. Every network-connected service listens on a specific port, and knowing which port corresponds to which service is essential for firewall configuration, network security auditing, software development, and system administration.

Port Number Reference covers 40+ of the most commonly used ports organized into categories: Web (HTTP/80, HTTPS/443), Email (SMTP/25, IMAP/143, POP3/110), Database (MySQL/3306, PostgreSQL/5432, MongoDB/27017, Redis/6379), Remote Access (SSH/22, RDP/3389, VNC/5900, Telnet/23), Security (VPN/1194, IPsec/500, TLS/443), File Transfer (FTP/21, SFTP/22, FTPS/990, SMB/445), Development (Docker/2375, Kubernetes/6443, Git/9418), DNS (53), DHCP (67/68), NTP (123), and more.

Each entry displays the port number, the transport protocol (TCP, UDP, or both), the standardized service name as defined by IANA, and a clear description of the service's purpose and common use cases. The search bar filters by port number, service name, or keyword instantly.

The port range reference at the bottom provides orientation: well-known ports (0-1023) require root/admin privileges and are assigned to widely used services, registered ports (1024-49151) are used by vendor applications, and dynamic/private ports (49152-65535) are used for temporary connections.

Real-World Use Cases for Port Number Reference

Configuring a Firewall to Allow Web Traffic

A network administrator needs to configure a firewall to allow web traffic. They reference Port Number Reference to confirm HTTP uses port 80/TCP and HTTPS uses port 443/TCP. The descriptions help them write appropriate firewall rules with correct documentation.

Auditing Open Ports on a Production Server

A security auditor runs a port scan on a production server and finds port 3306 open. They look it up: MySQL database. This is a security risk — database ports should not be exposed to the internet. They recommend moving MySQL to an internal network and closing the public port.

Debugging a Connection Refused Error

A developer cannot connect to a Redis cache server. They check that port 6379 is open on the server and that the application is configured to use the correct port. The reference confirms Redis default port is 6379/TCP. They discover the Redis server is listening on a different port.

Why Use Port Number Reference?

  • 40+ commonly used ports with descriptions
  • Search by port number, service name, or keyword
  • Port range reference (well-known, registered, dynamic)
  • Icons grouped by category (web, email, database, security)
  • One-click copy of any port number

How to Use Port Number Reference — Step by Step

1

Browse the port list or use the search bar.

2

Filter by port number, service name, or description.

3

Review protocol, service, and usage details.

4

Click Copy on any port to copy its number.

Who Is Port Number Reference Best For?

  • firewall configuration
  • network security auditing
  • software development
  • system administration

Pro Tips for Port Number Reference

  • 1Well-known ports (0-1023) require root/admin privileges to bind. When developing custom services on these ports, run your application with appropriate privileges or use a higher port and proxy traffic.
  • 2Port 8080 is commonly used as an HTTP alternative for development servers. It is not an IANA standard but is widely recognized as the HTTP-alt port for development and testing.
  • 3When troubleshooting connection issues, verify both the port number and protocol (TCP vs UDP). Some services use both — DNS uses UDP/53 for queries and TCP/53 for zone transfers.
  • 4Memorize the top 10 ports: SSH (22), HTTP (80), HTTPS (443), DNS (53), SMTP (25), MySQL (3306), RDP (3389), PostgreSQL (5432), MongoDB (27017), and Redis (6379). These cover 90% of daily networking tasks.

Port Number Reference — Frequently Asked Questions

What is the difference between TCP and UDP?

TCP is connection-oriented with guaranteed delivery — used for web, email, and file transfer. UDP is connectionless with no delivery guarantee — used for DNS, streaming, and real-time applications where speed matters more than reliability.

Why are some ports considered "well-known"?

Well-known ports (0-1023) are assigned by IANA to widely used services. Binding to these ports typically requires root/admin privileges. Examples include HTTP (80), HTTPS (443), and SSH (22).

Does the IP lookup store my searches?

No. The IP lookup API used by this tool does not log queries or store IP histories. Your searches remain private.

Can I look up private IP addresses?

Yes. The tool supports both public and private IP ranges (10.x.x.x, 172.16-31.x.x, 192.168.x.x). Geolocation data is available only for public IPs.

Is Port Number Reference really free to use?

Yes, Port Number Reference is completely free with no hidden charges, no usage limits, and no premium tiers. You can use it as often as you need without signing up or providing any personal information.

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