Common TCP/UDP ports reference
A searchable reference of well-known and registered network ports. Filter by port number, service or protocol.
| Port | Protocol | Service | Description |
|---|
How ports work
An IP address gets data to the right device; a port number gets it to the right program on that device. Combined, an IP and port form a socket — for example 93.184.216.34:443 is a web server listening for HTTPS. Ports run from 0 to 65535 and split into three ranges:
- Well-known (0–1023) — core services like HTTP, HTTPS, SSH and DNS, assigned by IANA.
- Registered (1024–49151) — reserved by specific applications and vendors.
- Dynamic/ephemeral (49152–65535) — temporary ports your device picks for outgoing connections.
TCP vs UDP
TCP is connection-oriented and reliable — it guarantees ordered, complete delivery, ideal for web pages, email and file transfer. UDP is connectionless and fast, trading guarantees for low latency, ideal for DNS, video calls and gaming. Some services (like DNS) use both.
Frequently Asked Questions
How do I check which ports are open on my computer?
Run netstat -an (Windows/macOS/Linux) to list listening ports, or use nmap to scan a host. Only open ports you actually need, and firewall the rest.
Is it safe to leave port 3389 (RDP) open to the internet?
No — exposed RDP is a top ransomware entry point. Put it behind a VPN, restrict it by IP, enforce strong passwords and multi-factor authentication, and never expose it directly.
Why does HTTPS appear under both TCP and UDP?
Traditional HTTPS runs over TCP on port 443. HTTP/3 uses QUIC, which runs over UDP on the same port 443, so modern web traffic can use either.