OneTaskBy Tim King · Updated
Port Number Lookup
Typical Services, Internet Exposure Risk and Safer Alternatives for Each Port
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How the Port Number Lookup works
This port number lookup tells you what normally runs on a TCP or UDP port and how risky it is to leave it open to the internet. Paste port numbers or service names, one per line or separated by commas, for example from a port scan or a firewall rule you are reviewing.
Reading the port number lookup results
Each port is matched against a built-in list of well known services, from web and mail ports to databases, remote desktop, file sharing and management interfaces. You can also type a service name such as rdp, redis or smtp to find its port.
The risk column is about exposure to the whole internet, not about the service itself. A web server on 443 is meant to be public. A database, Redis, Docker API or remote desktop port is not, and these are among the first things automated scanners look for. High risk means the port should normally be reached only over a VPN, an SSH tunnel or from an allowlist of addresses.
Numbers not in the list are reported as not found. Ports above 49152 are usually temporary client ports, while many others are used by specific applications and games, so check what is listening with ss -tlnp or netstat on the machine itself.
FAQ
Which ports should never be open to the internet?
Databases such as 3306, 5432, 1433, 6379 and 27017, remote desktop on 3389, SMB on 445, Telnet on 23 and container APIs such as 2375 are the usual list. Put them behind a VPN or restrict them to known addresses.
Does changing SSH to another port make it safer?
It cuts the noise from bots scanning port 22, but anyone scanning all ports will still find it. Key-only logins, disabled root login and an allowlist or VPN do the real work.
How do I see which ports are open on my server?
On Linux run ss -tlnp for TCP and ss -ulnp for UDP to list listening ports and the program behind each. Then check the firewall, because a port that is listening may still be blocked from outside.
See also: all Security & Identifiers tools, Dev Utilities, Formatters & Validators, Data & Encoding, SEO, Accessibility, AI.
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