📖 What is this tool?
Port Reference is a searchable directory of all common TCP and UDP port numbers and their associated services. Quickly look up what runs on any port — from well-known ports like 80 (HTTP) and 443 (HTTPS) to database and development ports.
🛠️ Common Use Cases
- Identify what service runs on a specific port
- Configure firewall rules correctly
- Debug connection refused errors
- Set up port forwarding rules
- Learn about common network services
❓ Frequently Asked Questions
What is a port number? ▾
A port is a virtual endpoint for network communication. Each service (HTTP, FTP, SSH) listens on a specific port number so that multiple services can run on the same IP address.
What is the difference between TCP and UDP? ▾
TCP provides reliable, ordered delivery (web, email). UDP is faster but unreliable — used for streaming, gaming and DNS where speed matters more than guaranteed delivery.
What ports should I keep closed on my server? ▾
Close any port you don't actively use. High-risk open ports include 21 (FTP), 23 (Telnet), 3389 (RDP) and 445 (SMB). Always use firewalls to restrict access.
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