2 entries are registered on port 631. It is a well-known port (0–1023) — assignments here are IANA's, and a service found on one is usually the service that was assigned it.
services registered on this number
2 transports in use
entries encrypted on the wire
1 of 2 iana-registered
| port | service | proto | category | risk | views |
|---|---|---|---|---|---|
| :631 | Internet Printing Protocol | TCPUDP | Network Services | caution | 10.0k |
| :631 | CUPS | TCPUDP | Network Services | caution | 9.3k |
The Internet Printing Protocol (IPP) is a network protocol used for distributed printing over IP networks. It allows clients to submit print jobs to networked printers, query printer capabilities, manage print jobs, and receive status updates, making it a widely adopted standard for modern network printing solutions.
port 631 as Internet Printing Protocol →The Common Unix Printing System (CUPS) is a modular printing system for Unix-like operating systems. It allows a computer to act as a print server, managing print jobs and queues and providing network printing capabilities across diverse platforms and devices.
port 631 as CUPS →The registry says what 631 is registered to. What is listening on it right now is decided by the host, and only the host can be asked. Each of these prints the process behind the socket.
ss -ltnp | grep ':631\b'lsof -nP -iTCP:631 -sTCP:LISTENnetstat -ano | findstr :631On Linux and Windows the process name comes back with the socket; on macOS lsof needs sudo to name a process that isn't yours. Match what it prints against the 2 entries above.
A port number is not a service. Anything may listen on 631 — what you actually met is decided by the host, not the registry. If a service is missing here, it belongs in the registry.
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