I've just installed Ubuntu Server on my home box after becoming partially familiar with it at work and wanting to train up as a Pen Tester.

I installed the latest version on a logical partition (the main one contained Win7), and selected none of the extra modules (I think). I installed ngrep and fired it up (along with TCPdump) and immediately saw some strange traffic which I am unable to identify.

My pc is sending out UDP packets every couple of seconds to a seemingly random series of IP addresses, all on the same port (47669 - though I did also see it use another port for a while).

I watched it do this for about 20 mins, whilst trying to work out why it was doing it. The only other traffic was the odd ARP request for the router and SSDP UPnP broadcasts from the router.

Anyone know what this is, or have any advice on how best to find out?

Thanks.

EDIT: Actually, it's not my box generating the traffic. It's receiving the traffic on that port, from a series of IP addresses, and returning 'port unreachable' messages.