Jump to content

Having trouble with hashfails


Dravonic

Recommended Posts

Recently came across a torrent that is causing me a lot of trouble with hashfails. 110 pieces downloaded, 143 hashfails, about 40 banned peers.

I've never seen anything of the sort even though I'm using utorrent for years. I find it hard to believe that so many bad peers are concentrated in this single torrent, when more than 200 others rarely get more than 3 hashfails, most getting none. It isn't even such a popular torrent (less than 2000 peers in the swarm). I believe I've encountered a/some malicious peer(s) that utorrent is having trouble to detect.

I've had a look around and thanks to the manual I found out it has 2 settings I can toy around with for banning peers, bt.ban_ratio and bt.ban_threshold. The threshold is easy to grasp, but the ratio is rather complicated when I have no idea what kind of calculations are involved. What are sane values I can use here? Or better yet, where can I find a detailed explanation of this ratio? Does anyone have any suggestions?

It is very likely that this guy is exploiting default values, meaning a bit of tweaking should help me out here.

Using utorrent 3.1.2 build 26753.

Link to comment
Share on other sites

No pattern at all. See for yourself:

[2012-02-19 15:03:03]  Banned 12.9.73.202:34917 until forever[2012-02-19 15:03:03]  Banned 186.29.38.77:34583 until forever[2012-02-19 15:03:03]  Banned 85.64.92.104:41276 until forever[2012-02-19 15:03:03]  Banned 41.224.215.84:56410 until forever[2012-02-19 15:03:09]  Banned 201.223.247.116:32150 until forever[2012-02-19 15:03:09]  Banned 24.63.61.89:44853 until forever[2012-02-19 15:03:53]  Banned 94.215.33.184:54740 until forever[2012-02-19 15:04:02]  Banned [2001:0:4137:9e76:10bd:2de9:9c11:8342]:34776 until forever

Just an excerpt, but it should be enough. Many simultaneous bans going on also, meaning utorrent really has no idea which one is the problematic one. Like here for example:

[2012-02-19 15:01:18]  Banned 84.215.150.196:46218 until forever[2012-02-19 15:01:18]  Banned 189.61.43.11:58625 until forever[2012-02-19 15:01:18]  Banned 190.45.58.14:20103 until forever[2012-02-19 15:01:18]  Banned [2001:0:5ef5:79fb:28df:3ff0:ae59:2183]:10105 until forever[2012-02-19 15:01:18]  Banned [2001:0:4137:9e76:1453:7d7:e7c0:c2a6]:44853 until forever

It just looks like these guys are being mistaken as bad peers due to a malicious one.

The hashfail banning code may handle bad peers properly, but a malicious one with knowledge of this ratio system can stay just above the ratio to avoid being banned, provided it's not so hard to do so. I actually have no idea if it is since I don't know the ratio formula being used.

Obviously, I considered a problem with my internet connection, which is why I made sure I had another torrent downloading. This was the only one getting hashfails. Of course this may not be a malicious peer problem at all, but I really have no idea what else would cause this.

Link to comment
Share on other sites

The hashfail banning code may handle bad peers properly, but a malicious one with knowledge of this ratio system can stay just above the ratio to avoid being banned, provided it's not so hard to do so. I actually have no idea if it is since I don't know the ratio formula being used.

It's actually quite difficult to do because the ban system is quite a bit more sophisticated than it first appears. The less peers involved in an individual piece the more accurate the ban.

The big causes are:

1> malicious peers

2> an effect that has been nicknamed "DLink DMZ Download Destroyer". Some routers have a bug that causes remapped packets with a 4-byte sequence that would match an IP address that would remap to become corrupt by the remap.

3> Corruption in the remote files caused by media indexer applications.

Link to comment
Share on other sites

Crap, could this be caused by dimwits using itunes or whatever and the program eventually modifies the mp3 metadata causing them to seed an altered file? Don't clients first check a piece's integrity before seeding it or part of it? Or they just assume a completed torrent is correct?

Link to comment
Share on other sites

Oh true, I completely forgot that. It will shift everything and cause a hashfail for the whole file, obviously :lol:

This being an MP3 torrent that certainly sounds more plausible than some guy corrupting the whole swarm this efficiently. But if so, this problem alone is causing me hashfails more than half of the time a piece is downloaded. Doesn't this happen often enough with these kinds of torrents it's reason enough to warrant a protocol change?

Link to comment
Share on other sites

  • 3 weeks later...

Hi

I'm running µTorrent 3.1.2 (build 26773) on Win 7 Enterprise x64 SP1. I have router model Telewell TW-EA510 v3©. I'm downloading torrent of size 13GB that includes multi .rar-files. The problems is that i get A LOT of hash fails.

[2012-03-06 15:33:04]  *** xxx: PIECE 647 FAILED HASH CHECK[2012-03-06 15:33:29]  *** xxx: PIECE 774 FAILED HASH CHECK[2012-03-06 15:33:58]  *** xxx: PIECE 647 FAILED HASH CHECK[2012-03-06 15:34:40]  *** xxx: PIECE 29 FAILED HASH CHECK[2012-03-06 15:34:47]  *** xxx: PIECE 647 FAILED HASH CHECK[2012-03-06 15:35:15]  *** xxx: PIECE 24 FAILED HASH CHECK[2012-03-06 15:35:45]  *** xxx: PIECE 29 FAILED HASH CHECK[2012-03-06 15:36:15]  *** xxx: PIECE 647 FAILED HASH CHECK

I'm downloading from private tracker. It seems that µtorrent doesn't even ban bad peers, only a few.

Do you know where m8 be a problem?

I also run pingtest http://www.pingtest.net/result/58365835.png

Link to comment
Share on other sites

If peers are getting banned on the logger tab, then you're dealing with either something in your setup being the cause or something going on in the swarm that is preventing the bans.

I got protocol encryption ON so I disabled it, but i still gettings this:

[2012-03-06 16:04:52]  *** xxx: PIECE 723 FAILED HASH CHECK

[2012-03-06 16:04:52] Banned 92.244.7.9:61657 until forever

[2012-03-06 16:06:09] *** xxx: PIECE 756 FAILED HASH CHECK

[2012-03-06 16:06:32] *** xxx: PIECE 527 FAILED HASH CHECK

[2012-03-06 16:06:56] *** xxx: PIECE 756 FAILED HASH CHECK

[2012-03-06 16:07:16] *** xxx: PIECE 527 FAILED HASH CHECK

here is my settings: http://dl.dropbox.com/u/56276014/settings.dat

Link to comment
Share on other sites

There may be a bug in your router's code causing the issue or the seeds have modified files that they're seeding that break.

Ok I try to reinstall/update the router's frimware. Can it be problem in HDD or what you mean by that "the seeds have modified files that they're seeding that break." ? Thanks anyway

Link to comment
Share on other sites

  • 1 month later...

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...