I ran an nmap scan against myself from a separate network. The results came back as this:

Not shown: 1675 filtered ports
PORT STATE SERVICE
80/tcp open http
1720/tcp open H.323/Q.931
3128/tcp open squid-http
6000/tcp closed X11
6001/tcp closed X11:1
6002/tcp closed X11:2
6003/tcp closed X11:3
6004/tcp closed X11:4
6005/tcp closed X11:5
6006/tcp closed X11:6
6007/tcp closed X11:7
6008/tcp closed X11:8
6009/tcp closed X11:9
6017/tcp closed xmail-ctrl
6050/tcp closed arcserve

Nmap finished: 1 IP address (1 host up) scanned in 25.000 seconds

I have a firewall up (ipcop) I would assume that it would block most of this from showing up to the outside world. Even before this, most of this showed up when I ran this. I thought perhaps it was the router or modem doing this? Router is out of the equation now. Any ideas?

What about these others, arcserv, xmail-ctrl, squid-http (from ipcop? I haven't set it up yet), H.323/Q.931 (what is this?)

Thanks for any insight.

It could be that your ISP is filtering some ports to cut down on the traffic they receive and prevent their customer machines from being exploited. The best way to test a firewall is to plug a machine directly into it's external NIC with a crossover cable, or put a machine on the same switch as the external NIC, and scan from there. That way you can rule out ISP.

Okay great. I'll try that out and we'll see how the results look after that.