# WHATPORT(6881)

## NAME

port 6881 — BitTorrent peer — The classic BitTorrent peer-listening port — first in the 6881-6889 range clients try.

Protocol: TCP  
IANA registry

## DESCRIPTION

BEP 3, the BitTorrent protocol specification, describes the convention directly: "Common behavior is for a downloader to try to listen on port 6881 and if that port is taken try 6882, then 6883, etc. and give up after 6889." The port carries peer-to-peer connections in the swarm, not tracker traffic, and it is an inbound listener so other peers can reach you. IANA never registered it — the whole 6869-6887 block is Unassigned — and most modern clients now randomise the port or take it from a UPnP mapping, so 6881 mainly turns up on older or default-configured clients.

## EXPOSURE

**Expose with care.** The port is meant to be reachable, and a working swarm needs it, but an open 6881 publicly advertises that this host runs BitTorrent and is routinely logged by swarm monitors. Expose it deliberately, on a host where that is fine.

## CHECK

```sh
nc -vz TARGET 6881
```

## SEE ALSO

- spec — [BEP 3 — The BitTorrent Protocol Specification](https://www.bittorrent.org/beps/bep_0003.html) (bittorrent.org)
- iana — [IANA Service Name and Transport Protocol Port Number Registry — 6881](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=6881) (iana.org)

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HTML: <https://whatport.net/6881/> · JSON: <https://whatport.net/6881.json> · full dataset: <https://whatport.net/ports.json>