A year ago, I ran into a problem with Skype squatting on port 80, which I had long forgotten about. Today, I ran into one with Skype squatting on port 443.
I was trying to set up SSL on my Windows Server 2003 dev box. My ultimate goal is to experiment with client certs and server certs for SOAP, but that’s a story for another time. I was running into all kinds of strange problems, exacerbated by the relatively strange IIS configuration on my machine.
I tried SslDiag. In hindsight, it pointed me towards the underlying problem, but I couldn’t see it at the time. I did a lot of digging around on Google. Eventually, a newsgroup thread on ListenOnlyList gave me CurrPorts, which showed me that Skype was listening on port 443. I suppose netstat -anob, TcpView, or Port Reporter would have told me the same thing, though CurrPorts had the friendliest view. WFetch from the IIS 6 Resource Kit Tools was also useful in looking at raw requests and responses.