How torrent works behind a firewall

[royalroy]

My ISP blocks all incoming ports to my residential connection. How does torrenting work in such a scenario? I get that my torrent client may connect to other people who have active incoming ports. But I also see people from my same ISP peering with me. How does this work?

 

[a.c]

If Upnp is on then everyone on the same isp is relatively on a large LAN network. This is not the case with every isp but works on most local isps.

 

[royalroy]

Yeah, I thought about that at first. But Upnp is disabled on my router. Also, the peers have public IPs and not private IPs, which should have been the case if we were connected over a LAN.

 

[JB701]

NAT PMP? NAT Port Mapping Protocol - Wikipedia

 

[a.c]

Just check your port with canyouseeme. If it's open then it's some kind of nat pmp else, the other person with public IP has port forwarding working. You can confirm the latter with "nc -v IP PORT" if it says connected successfully it means the other person has open port.