I created a test torrent using
mktorrentand added some open trackers to it. I am seeding this torrent using
HostA, which is using
qBittorrent4.3.7. It is on port
32123, which is forwarded correctly in my router for both TCP and UDP.
I then tried to download the torrent using
HostB. This is the output:
ubuntu@HostA:~$ aria2c testtorrent.torrent --console-log-level=debug | grep '32123' 09/21 13:00:34 [DEBUG] Checkout peer HostA:32123 to CUID#48 09/21 13:00:35 [INFO] CUID#48 - Connecting to HostA:32123 09/21 13:00:35 [DEBUG] CUID#48 - Peer HostA:32123 banned. 09/21 13:00:36 [INFO] CUID#48 - Connecting to HostA:32123 09/21 13:00:36 [INFO] CUID#48 - To: HostA:32123 handshake peerId=A2-1-35-0-%00%A8%21n2%2C%E8%CD%B8%EC, reserved=0000000000100005 Exception: [PeerConnection.cc:215] errorCode=1 Got EOF from peer. 09/21 13:00:36 [DEBUG] CUID#48 - Peer HostA:32123 banned. 09/21 13:00:36 [DEBUG] Peer HostA:32123 returned from CUID#48
Here is a packet capture between the two hosts (
I would think my ISP might be interfering, but the
[FIN, ACK]comes from
After extensive testing*, I was able to fix this issue by enabling “Allow multiple connections from the same IP address” in qBittorrent. You can see evidence of multiple connections in the Wireshark screenshot, where HostB sends two packets before HostA can respond.
* This included making my own tracker, connecting over LAN, using a VPN, using a cloud load balancer, and more.