Unknown open port: "6881/tcp open bittorrent-tracker" found with nmap

Hi. I ran nmap on my server, and I get the following:

Starting Nmap 4.76 ( http://nmap.org ) at 2009-03-19 16:33 EDT
Interesting ports on -------- (-----):
Not shown: 997 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
6881/tcp open  bittorrent-tracker

The first two are as I want, but I am not running anything bittorrent related (at least I'm not intending to). What tool can I use to manage my open ports or see what processes are causing this?

I'm running Debian 2.6.18-6 (powerpc)

Thanks for any help!

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EDIT: Solved! I was running nmap on the router, not the server itself. Someone using a computer locally was running Bittorrent. Silly me.