why utorrent doesn't automatically ban peer after 5th hashfails?

[tasso85]

this is something I'm unable to explain... I never changed settings about the way uTorrent ban peers which cause too much hashfails...

but still, if I go to the peer tab, I can see that some peer have already caused 7-8 hashfails without being banned!

why is this happening? shouldn't utorrent automatically ban them after the 5th hashfails?

what can I do, except bannig them manually using ipfilter.dat?

help please, if you can! I use uTorrent version 1.7.2

PS: what is the bt.ban_ratio in the advanced options? should I change that value?

EDIT:

i read the guide, but still don't understand what bt.ban_ratio is used to... can someone explain to me, please?

[Switeck]

Ok, firstly do you understand that more than 1 peer can be responsible for a piece failing hash?

Because of that, 1 hostile can come along and give a bad 16 KB section of a 256 KB-or-larger piece and every peer that uploaded part of that piece to you would be a "possible suspect" for the reason why the piece failed hash.

The hostile doesn't care if/when it gets banned, because the really hostile ones have a PLAN: since they have multiple ips (you'll often see a LOT of ips in a narrow range, changing only the last ip number), each one only has to send out 1 bad 16 KB section to you to sabotage alot of other peers' and seeds' uploads to you. So hostiles typically end up with only 1 "hash failed" strike against them, but fast peers and seeds quickly gather MANY. So only the real and good peers and seeds end up banned.

µTorrent's NEW banning procedure tries harder to sort the good from the bad -- seeing if peers and seeds have ever sent GOOD pieces to you. Because if they have, then likely they're not the ones responsible for the hash fails. This is why there's a ratio of good-to-bad, instead of the default old method of just auto-banning every peer or seed that gathers 5 (or more) hash fails strikes against it.

[tasso85]

ok, now I understand! I used to think that, after the 5th error, the peer got banned and stop!

so, what does bt.ban_ratio represents? mine is set to 128: does this mean that a peer, even after 5 hashfail, if it has sent me a minimum of 128 good pieces, is allowed to stay? or is it a minimum of 128 pieces FOR EACH hashfail?

and now, a little curiosity: would it create too much overhead to make an hash check on each 16k piece? this way, it could be easier to identify "enemies"!

[Ultima]

Yes, it'll cause a lot of overhead to have pieces even being that small (let alone creating/using torrents with a 16KB piece size).