What is the difference between well-known, registered and dynamic ports?

IANA splits the port space into three ranges. Well-known ports (0–1023) are assigned to core services and usually need elevated privileges to bind. Registered ports (1024–49151) are assigned to specific applications on request. Dynamic or ephemeral ports (49152–65535) are not assigned and are used for the client side of outbound connections.

Can the same port number use both TCP and UDP?

Yes. IANA often reserves a number for both transports for a single service — for example DNS uses both UDP and TCP on port 53. The tool shows which transports each entry covers.

Does a service have to run on its standard port?

No. Standard ports are conventions, not rules. An administrator can run any service on any free port, and many do for security or to avoid conflicts. The lookup tells you the conventional assignment, which is what clients expect by default.

Why does my firewall block some of these?

Many networks block or restrict ports tied to risky or noisy services — like Telnet (23), SMB (445), or RDP (3389) on the public internet — because they are common attack targets. Blocking is a policy choice, independent of the IANA assignment.

Is my search uploaded anywhere?

No. The port list ships with the page and all matching happens locally in your browser.

TCP/UDP Port Lookup — Gera Tools

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Find what runs on a port — or which port a service uses

When you see traffic on port 5432 or need to know where to point a client for redis, this tool answers both directions. Search by a port number to see the conventional service, or by a service name to find its standard port — along with the transport protocol (TCP, UDP, or both) and which IANA range the number falls in.

How it works

The page carries a curated list of common port assignments, each with its number, the transports it uses, a service name, and a description. A numeric query is matched exactly against the port number and is also classified into one of the three IANA ranges: well-known (0–1023), registered (1024–49151), or dynamic/ephemeral (49152–65535). A text query is matched case-insensitively against the service name and description, so mail surfaces SMTP, IMAP, and POP3 entries together. Results show every transport the service is registered for.

Tips and notes

Binding to a well-known port (below 1024) normally requires root or an explicit capability on Linux, which is why services like web servers often drop privileges after binding. Standard ports are conventions: clients default to them, but any service can be moved to a free port. On the public internet, treat exposure of high-risk ports — Telnet (23), SMB (445), RDP (3389), database ports — as something to firewall by default. This list covers common assignments; the full IANA Service Name and Transport Protocol Port Number Registry is authoritative for the long tail.