# WHATPORT(179)

## NAME

port 179 — BGP — Border Gateway Protocol — the sessions that exchange the internet's routing table.

Protocol: TCP  
IANA registry

## DESCRIPTION

BGP-4, RFC 4271, runs over a plain TCP session on port 179 between two configured peers that exchange UPDATE messages describing reachable prefixes and their AS paths. Every internet exchange, transit link, and large enterprise edge is built from these sessions, and route servers, FRRouting, BIRD, and vendor routers all listen here. A BGP speaker only accepts sessions from peers you configure, so an open 179 is a router edge, not a public service. Peers commonly authenticate the session with a TCP-MD5 or TCP-AO key.

## EXPOSURE

**Expose with care.** 179 is necessarily reachable by your peers, but it should be restricted to configured neighbor addresses with session authentication and GTSM (TTL security) — never open to the internet at large.

## CHECK

```sh
nc -vz TARGET 179
```

## SEE ALSO

- spec — [RFC 4271 — A Border Gateway Protocol 4 (BGP-4)](https://www.rfc-editor.org/rfc/rfc4271.html) (rfc-editor.org)
- spec — [RFC 7454 — BGP Operations and Security](https://www.rfc-editor.org/rfc/rfc7454.html) (rfc-editor.org)
- source — [FRRouting source repository](https://github.com/FRRouting/frr) (github.com)
- iana — [IANA Service Name and Transport Protocol Port Number Registry](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml) (iana.org)

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HTML: <https://whatport.net/179/> · JSON: <https://whatport.net/179.json> · full dataset: <https://whatport.net/ports.json>