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I am trying to send some files to my friend which unfortunately are too big to be sent via email. So I tried creating a torrent file so he can download them as a normal torrent. However it doesn´t seem to be working so far. His pc and mine are not connected and the up/down is always 0/0. The last time I tried this was many years ago, when we both still had winXP and it worked perfectly without much work.

However now it seems to be a problem. I have now tried several things to exchange a torrent between my pc and my laptop which are on the same network:

  1. creating very small torrents(files ~100Kb) just to try it
  2. marking and unmarking the torrent as private
  3. adding my ip:port as a tracker
  4. adding many different trackers

However, none of the above have turned out to be successful so far. If that helps, I am currently running on win10 and my laptop on win7. Can it be something with the firewall settings? In my bittorrent client the TCP-port is marked as blocked by firewall even though I added an exception for it. And if yes, wouldn´t this problem just reduce the up/down-speed and not just block the entire connection? Worth mentioning that when I download a normal torrent, it works without any problems. Has anyone had a similar problem or has any tips for me?

Thanks in advance!

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    These days it's got to be a whole lot simpler to just use a dedicated service, such as WeTransfer which is free for up to 2GB per transfer.
    – Tetsujin
    Commented Aug 6, 2020 at 9:48

2 Answers 2

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Assuming at least one of the two computers has the incoming port used by the torrent application open and accessible from the outside (i.e. correctly forwarded on the router), all you need to do is add the ip:port to the other computer as a peer in the shared torrent (not as a tracker, unless the computer is also running a tracker, and the tracker port is open to the outside). No tracker is required for this test, which of course you can do also on a local network, using the local network address (unless the router has something like "client isolation" enabled).

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    It worked perfectly! I fixed my port forwarding and indeed, only one of us was "needed" to have an open port, my friend then added my ip:port manually as a peer! Commented Aug 10, 2020 at 22:30
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As you're on the same LAN, it's very likely that your computers do not have individual public IPv4 addresses and are just borrowing the single address that your LAN router has.

So that creates a problem with peer discovery: trackers and DHT will record your public IPv4 addresses, but as you both are behind the same router, connecting to that address from inside will usually just not work at all. On the other hand, you do have private (LAN) IPv4 addresses, but as far as I know, trackers and DHT do not record those.

You might have some luck if you enable "Local Peer Discovery" in your clients (which additionally requires UDP port 6771 to be allowed in your firewall).

adding my ip:port as a tracker

Generally, BitTorrent clients don't have tracker service built in.

In my bittorrent client the TCP-port is marked as blocked by firewall even though I added an exception for it.

The client doesn't exactly know which firewall is blocking it. All it knows that it's not able to receive connections from whatever online "test helper" server.

This usually means that the specified ports haven't been "port forwarded" on your home router. (With most residential ISPs, the router is the only device with a public IPv4 address and .)

Of course, port-forwarding does not prevent direct connections within the same LAN... but your client's "port test" feature doesn't know you're planning to do that. It expects that you'll be communicating with peers on the Internet, like most users do.

And if yes, wouldn´t this problem just reduce the up/down-speed and not just block the entire connection?

No, that's incorrect. If it's blocked, then it's blocked: it does not work.

You have to understand why people say "blocked ports make downloads slower" – it's not about individual connections becoming slower due to blocking, it's that they reduce the number of peers you're able to connect to.

For example, if there are 100 hosts in the "swarm", but only 20 of them are able to receive incoming connections, then the remaining 80 can only exchange data with those 20 and not directly between each other. So it's not blocking in itself that makes things slower – it's just that those 20 hosts might be unable to provide enough bandwidth to everyone at the same time.

In your case, when you have only 1 peer and neither of you is able to connect to the other, then a connection cannot be made; you have 0 peers.

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  • Thank you very much for the detailed explanation! Commented Aug 10, 2020 at 22:31

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