To connect to other computers, TeamViewer does not need additional firewall settings. And in most cases, the program will work correctly if surfing on the network is allowed.
But in some situations, for example, in a corporate environment with a strict security policy, the firewall can be configured so that all unknown outgoing compounds will be blocked. In this case, you will have to configure the firewall so that it allowed TeamViewer to connect through it.
Sequence of using ports in TeamViewer
TCP / UDP - port 5938. This is the main port for the program. Firewall on your PC or on the local network should allow packet passage through this port.
TCP - port 443. If the TeamViewer cannot connect via port 5938, it will try to connect via TCP 443. In addition, TCP 443 is used by some TEAMVIEWER modules, as well as a number of other processes, for example, to check the program update.
TCP - port 80. If the TeamViewer cannot connect either through port 5938, nor through 443, it will try to work through TCP 80. The connection speed through this port is slower and less reliable due to the fact that it is used by other programs, for example, browsers, and through this The port does not automatically connect in the event of a break bursting. For these reasons, TCP 80 is used only as the last means.
To implement a strict security policy, it suffices to block all incoming connections and allow the outgoing port 5938, regardless of the IP address of the destination.