Gotcha Of The Day - Skype Steals Port 80

This morning, I went to test some changes I've made to a customer's web app locally, and was greeted with a totally blank screen. I undid my changes. Still nothing. I tried another browser. Still blank. I then checked the Apache access log, sure enough, the web requests weren't reaching it.

I then remembered that I had this problem a few weeks ago, fixed it, but never documented it. Turns out, Skype will grab port 80 and use it for its own purposes. This meant that Apache couldn't start up. The issue is explained here:

To get port 80 back for your Webserver, either start the server before Skype, or more efficient, disable use of Port 80 by Skype in Skype's connection options! (Same checkbox applies for port 443)

Sure enough, in Skype, you can select:

I'm sure the good people at Skype have an important reason for stealing port 80, but still, I think that takes serious chutzpah to grab a port you have no business running on.

I wish I could recall how I figured out Skype was the culprit. I probably used the networking sysinternals tools to debug it. But I don't recall which tool I used.