# WHATPORT(9003)

## NAME

port 9003 — Xdebug (DBGp) — Xdebug 3's default debug port — the IDE listens, PHP connects back to it.

Protocol: TCP  
IANA registry

## DESCRIPTION

Xdebug 3 changed its default from 9000 (which collided with PHP-FPM) to 9003 for xdebug.client_port, and the DBGp command-line client uses the same number. The direction surprises people: the debugged PHP process is the client, and your editor or IDE is the thing listening on 9003. So a listener here is almost always a developer's IDE, and IANA has 9003–9004 marked Unassigned.

## EXPOSURE

**Do not expose.** A DBGp listener accepts a debug session from anyone who can reach it and lets that session evaluate code in the debugger's context; bind it to loopback and reach remote hosts over an SSH tunnel.

## CHECK

```sh
sudo lsof -nP -iTCP:9003 -sTCP:LISTEN
```

## SEE ALSO

- docs — [Xdebug — settings (xdebug.client_port, default 9003)](https://xdebug.org/docs/all_settings) (xdebug.org)
- source — [xdebug/xdebug on GitHub](https://github.com/xdebug/xdebug) (github.com)
- iana — [IANA Service Name and Transport Protocol Port Number Registry — 9003](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=9003) (iana.org)

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HTML: <https://whatport.net/9003/> · JSON: <https://whatport.net/9003.json> · full dataset: <https://whatport.net/ports.json>