Scan of ubuntu with Teamviewer: Nmap no open ports

Question

I'm just trying some things and figure out that a scan with map of a ubuntu system which runs Teamviewer returns no open ports. So the target machine has running teamviewer and I scanned all ports where teamviewer could be listening, but always nmap returns these ports are not open. After this I connected with the teamviewer to the target. So this was succesful. I scanned a second time the ports but still nmap does not find any open ports.

So my question is why?

Answer 1

It's likely that TeamViewer connects out to a server hosted by teamviewer, and receives connections via that outbound connection.