2 entries are registered on port 6891. 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
0 of 2 iana-registered
| port | service | proto | category | risk | views |
|---|---|---|---|---|---|
| :6891 | BitTorrent Data Transfer | TCPUDP | File Transfer | caution | 9.9k |
| :6891 | Windows Live Messenger File Transfer | TCPUDP | File Transfer | caution | 5.8k |
Port 6891 is commonly used by BitTorrent clients as part of a range of dynamic ports essential for peer-to-peer file transfer. It facilitates the exchange of data chunks between peers, enabling efficient decentralized distribution of large files. Since BitTorrent dynamically selects ports within a broad range, 6891 is one that often appears during torrenting activity.
port 6891 as BitTorrent Data Transfer →Port 6891 is traditionally used by Windows Live Messenger to manage peer-to-peer file transfers. It facilitates the initiation and transfer of files between clients by creating direct connections, bypassing centralized servers. Both TCP and UDP protocols enable flexible data transfer, supporting reliable delivery and real-time connectivity during file sharing sessions.
port 6891 as Windows Live Messenger File Transfer →The registry says what 6891 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 ':6891\b'lsof -nP -iTCP:6891 -sTCP:LISTENnetstat -ano | findstr :6891On 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 6891 — 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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