Skype trying to receive incoming connections

Hi all, I’m not very knowledgable when it comes to computer security so please excuse any outright dumb questions.

I have the latest version of CIS, set up according to Chiron’s guide. I received a pop-up asking if I want to allow Skype to receive an incoming connection (IP address did not belong to Microsoft). Source port was 9045 and destination port was 39611. I had stupidly forgotten to configure Skype, so the settings allowed UPNP, and calls from people not even in my contact list, among other things. However, I received no prompt from Skype that anyone was calling me. I have two questions:

  1. Is it normal to receive a pop-up for an incoming connection when I’ve already set up my firewall to stealth all ports and block incoming connections? Should I begin to wonder if my system’s been compromised or that my installation of CIS is corrupted?

  2. If we assume someone could gain access to your computer through Skype, would running Skype in a sandbox prevent any such user from making permanent changes to your system?

Thanks.

Hello!

  1. Yes. Don’t worry. It happens time to time. Just block the request.

  2. Broad Q. It dep on many things.