2 entries are registered on port 4000. It is a registered port (1024–49151) — IANA records an assignee, but nothing stops other software from listening here, which is why the number carries more than one entry.
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 |
|---|---|---|---|---|---|
| :4000 | Diablo II | TCPUDP | Gaming | caution | 4.3k |
| :4000 | Terabase | TCPUDP | Voice and Chat | safe | 0 |
TCP/UDP port 4000 is primarily known for facilitating the multiplayer connections of the classic Blizzard game Diablo II. The port allows players to connect to Battle.net servers or direct peer-to-peer sessions, enabling matchmaking, in-game communication, and other gameplay features.
port 4000 as Diablo II →TCP/UDP 4000 is assigned to Terabase and has a documented historical conflict with ICQ messaging.
port 4000 as Terabase →The registry says what 4000 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 ':4000\b'lsof -nP -iTCP:4000 -sTCP:LISTENnetstat -ano | findstr :4000On 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 4000 — 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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