I have been testing this "bittorent sync" software (a peer to peer application) as an experiment. I decided to block the application using the Windows firewall on the computer that is running the software. I then tried to sync from external computer outside the LAN and it still worked fine.
I then went to my router and disable UPNP and reboot and I am still able to connect to my machine; I made sure that I block all TCP and UDP from external access and this thing is still transmitting UDP packets.
How does this technology work? Is it firewall proof? Do i need a firewall that read each packet to block it? I know that some firewalls allow you to explicitly block peer to peer applications, is that what is needed in this case?
I am a little confused please help...