Thread: Using the download from one tracker to upload to another...

This is a bit of a technical question. I know you can use the download off of one tracker to upload to a different tracker. However, sometimes I've noticed that the two torrents will have identical files except in one of them. Someone took out the sample video for example. The rest of the files are identical. My question is will you be able to perform this little trick if just one file is missing or different? You should be able to right? I guess I'm trying to figure out if the torrent computes some kind of hash for all the files together or for each file independently. I don't really want to experiment for fear of getting accused of something I shouldn't be doing.

Thanks for any insight.

I guess you can as long as the individual file CRC is the same.
It starts with checking the directory and then starts seeding/downloading.

Don't you just force recheck it and it'll show what % you have and start downloading the stuff you don't have?

Are you trying to be the initial uploader? Or are you trying to re-seed a torrent you got on one site on another site?

If it's the first one, I suggest you read my tutorial on cross seeding as it is tricky and there are a few ways to get banned if you don't look out.

If you are just trying to cross seed and not actually be the uploader, all you have to do is add the new .torrent, point it to your existing files, skip the hash check (optional), and you're good to go. Cross seeding benefits the swarm health, and is not looked down upon by trackers. Cross seeding is the best technique for attaining huge buffers w/o scene axx.

Originally Posted by s2cuts

This is a bit of a technical question. I know you can use the download off of one tracker to upload to a different tracker. However, sometimes I've noticed that the two torrents will have identical files except in one of them. Someone took out the sample video for example. The rest of the files are identical. My question is will you be able to perform this little trick if just one file is missing or different? You should be able to right? I guess I'm trying to figure out if the torrent computes some kind of hash for all the files together or for each file independently. I don't really want to experiment for fear of getting accused of something I shouldn't be doing.

Thanks for any insight.

Actually, bittorrent doesn't work by computing hashes for the whole file or the whole torrent simultaneously. When a torrent is created, a specific "chunk" size is chosen, ranging in size from 16 kb to 4096 kb. Every single one of these chunnks is then hashed separately, and these chunks are what your torrent client actually negotiates the transfer of. Each chunk can span across multiple files or describe just a small part of a single file. It all depends on the data. An overall hash value is also computed, but that is really not used when checking the integrity of files. Its primary purpose is to identify the download on a trackerless torrent/to the tracker itself and to ensure that two completely identical torrents are not loaded simultaneously (in some clients). And actually, if I remember correctly, the overall hash is not actually a hash of the files themselves, but rather a hash of the metadata (of the torrent). I'm sure you could find the documentation for it quite easily. It's been a while since I've thought about it.

So, in other words, cross-seeding without having, for example, a sample file, would work perfectly, but your torrent client would want to download the sample file from the tracker you are cross-seeding to. You could, of course, set the client to not download these pieces. But if your ratio is so bad that you're worried about download a sample file.... well...

I have a folder for each one of the trackers I use. When I want to cross seed, I copy the whole folder for the torrent from one tracker to the new one, and point at that. You can have issues with two active torrents going at the same folder. I just don't do it. I have enough harddrive space that doing this isn't an issue.

Originally Posted by VladTheRipper

I have a folder for each one of the trackers I use. When I want to cross seed, I copy the whole folder for the torrent from one tracker to the new one, and point at that. You can have issues with two active torrents going at the same folder. I just don't do it. I have enough harddrive space that doing this isn't an issue.

Yep if you have tons of HD space that's a concrete way of doing it (i.e. no client will give an error this way), but for those on seedboxes where space IS an issue, use uTorrent. Every client I've tried (rtorrent, deluge, transmission, etc) there are errors that come up when doing serious cross seeding. With uTorrent you can cross seed your heart out without running into errors.

Originally Posted by polarbears

Don't you just force recheck it and it'll show what % you have and start downloading the stuff you don't have?

This is true, Ive cross-seeded before and if im missing something like an nfo file thats in one torrent it will just download whatever i dont have and seed once its 100%

I heard someone got banned from TL for cross-seeding. Reason as told in support channel was ratio cheating.

Be careful!

In reference to what okgg said, they were using BitTornado.