2 entries are registered on port 751. 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 |
|---|---|---|---|---|---|
| :751 | Kerberos Master Authentication | TCPUDP | Security | safe | 7.8k |
| :751 | PUMP Protocol | TCPUDP | Network Services | caution | 5.3k |
Port 751 is utilized primarily for the Kerberos master authentication service, an integral part of the Kerberos network authentication protocol. It helps facilitate secure communication for verifying user identities over insecure networks by acting as a central key distribution hub.
port 751 as Kerberos Master Authentication →PUMP (Packet Usage Measurement Protocol) is an official experimental protocol designed to facilitate usage measurement and accounting on IP networks. It operates on both TCP and UDP port 751, enabling flexible communication options. Despite its limited adoption, it has historical significance in early network accounting concepts.
port 751 as PUMP Protocol →The registry says what 751 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 ':751\b'lsof -nP -iTCP:751 -sTCP:LISTENnetstat -ano | findstr :751On 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 751 — 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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