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Bram Cohen: Private Sites to Blame for Ratio Cheating.

Bram Cohen: Private Sites to Blame for Ratio Cheating.

The creator of BitTorrent refuses to help private BitTorrent trackers, accusing them of being destructive to sharing. Despite the increasing sophistication and potential disruption posed by the latest generation of ratio cheating software, BitTorrent creator and developer Bram Cohen has reiterated his refusal to change the protocol.

Some private BitTorrent trackers monitor their members to ensure users upload as much as they download. Supporters say monitoring the upload/download ratio encourages sharing, resulting in faster download speeds. Those who do not reach the minimum ratio are normally banned from using the tracker.

To monitor user ratios’, trackers depend on clients reporting their true upload and download statistics. Programmers are increasingly exploiting this vulnerability by developing software which falsifies upload and download reports to the tracker.

The exploit was first widely publicized over a year ago, but no solution has yet been found. Only standard code is sent to the tracker, which is impossible to verify using the current BitTorrent protocol.

As ratio cheating software is becoming easier to use and more readily available, the pressure is on Bram Cohen and BitTorrent Inc. to update the protocol to catch ratio “cheats”.

However, Bram Cohen has told Zeropaid that he stands by the comments he made in 2005, arguing that ratio monitoring is destructive to sharing.

“[Leechers are] engaging in perfectly reasonable and non-destructive behavior and the site is trying to punish him for it, thus fostering the creation of clients which lie about their statistics. This is the site’s fault, and the result could do serious damage to the value of BitTorrent statistics generally. Sites which do this are being extremely destructive, and the way they grandstand about how they’re fostering sharing really ticks me off,” he said.

Bram argues that the tit-for-tat nature of protocol is sufficient enough to stop destructive leeching. The BitTorrent protocol is robust enough to handle file sharers who limit their upload and do not seed after the file has finished downloading.

“Even if almost everyone quit the instant their download was completed you’d still have decent download rates, they’d just be closer to everyone’s upload rates,” he explains.

By definition this means download speeds will be slower, which could easily be classed as “destructive”.

Still, according to Cohen, the alternative of monitoring ratios is worse.

“What typically happens in a single torrent is that at the beginning upload and download ratios are reasonably correlated, then over time people finish downloading, and some of them leave, but a significant number of seeds remain. After a while there’s a period of time where there are many more seeders than downloaders. Anyone who joins the torrent at this late time will be generally get a download rate limited by their download capacity, and anyone who tries to upload to them will only be able to do so at a low rate. Such people will have very out of whack upload/download ratios, but they’re downloading from otherwise unutilized upload resources, and hence not being anywhere near the drain on the system that their total upload/download ratio indicates,” he explains.

“Just a little bit of threatening to ban people can get the overall balance to be very heavily weighted on the side of uploading, making it difficult for people to accomplish a reasonable amount of upload even if they try.”

To encourage sharing beyond the tit-for-tat system, Cohen suggests that user ratios should not be monitored at the peak of each swarm, or if a torrent is heavily seeded. Alternatively, he suggests adapting an alternative method for calculating the ratio, which takes into consideration the health of a torrent:

“When a client reports new downloads to the tracker, the tracker can multiply the amount by (number of current peers total – number of current seeds) / (number of current peers total) and add that to the ‘total downloaded’. This results in most people having a ‘ratio’ of more than 1, but that isn’t actually a problem unless you’re more interested in mathematical purity than practical behavior.”

So far, the BitTorrent world has not been turned on its head by ratio cheating software, but there is no accounting for the future. Without support from BitTorrent Inc. to upgrade the protocol, private tracker administrators who want to keep ratio monitoring may be forced to develop a new protocol.

*Editor’s Note: This story is a follow up to a previous article

BitTorrent Ratio Exploit Software on the Increase

Jared Moya
I've been interested in P2P since the early, high-flying days of Napster and KaZaA. I believe that analog copyright laws are ill-suited to the digital age, and that art and culture shouldn't be subject to the whims of international entertainment industry conglomerates. Twitter | Google Plus
evilmegaman
evilmegaman

well I can't say I disagree with bram. Forcing people to do something they don't want to do isn't the way the internet should be. Plus bram doesn't believe in illegal filesharing so much so he has a right to not want to work for something he doesn't believe in.Way to go bram!

soulxtc
soulxtc

I tend to agree. My only hesitation is that perhaps he's slightly jaded by the fact that he had to go legit after getting sued.

evilmegaman
evilmegaman

That's true. but iirc I think he's always had that stance though

soulxtc
soulxtc

But his thoughts are that everything will find its own equilibrium my ability to change anything be dammed.

cjules13
cjules13

I like the idea of the formula used to calculate ratios. When's there's idle upload bandwidth availble who cares but only a couple seeds then you need to stay.

soulxtc
soulxtc

Exactly.......its only the real "high demand" stuff that one need not worry about share ratios but for the rare and odler items you need seeders. Plus it seems pretty galling to take a whole download but then only upload or share anything less you know?

shawners
shawners

If he doesnt like what a private site does then just dont sign up. The message is at the door the rules are written. Each site is responsible for their site what it takes to make it. When a private site is created it doesnt start out with 30 thousand or 95 thousand users who are willing to seed. It starts with a few hundred which gain ratio more people come in more download and seed. People upload their own stuff depending on if its a 0-day site only. And people begain inviting others and others come in. They like it they want to support it. Yet the site needs seeders to attract the larger group. If i saw 1 seeder to 50 leechers on alot of torrents it would discouraging me from downloading. Seeds stay alive longer because they want to share or be a member of it. Its up to each site to run it the way they want. He is paid by hollywood of course he be against something that hollywood cant see which is behind a gated torrent community that distribute if not all of HOLLYWOOD movies.

PacoBell
PacoBell

Leechers per swarm weighting multiplier huh? Interesting concept akin to a regressive tax. So the individual ratio becomes irrelevant. It only becomes significant when compared to the rest of the community population. Why is this starting to sound like the eMule credit system? ;)

dosirrah
dosirrah

Bram didn't explain it well and Zeropaid is misrepresenting what he did say.Share ratios as implemented are broken. In at least two typically occurring scenarios STARVATION CAN OCCUR: 1) when a torrent is well seeded 2) when many torrents are unpopular.When a torrent is well seeded it may take an enormous amount of time to give back as much as a well-meaning user takes. In the extreme if there are many well-connected seeds it is possible that a well-meaning user with slightly smaller upload pipes never gets a chance to upload to anyone. If share ratios are enforced the well-meaning user can be locked out of the tracker forever.When a tracker has many unpopular files that are nonetheless seeded if a well-meaning user downloads some of these unpopular files they can find themselves with a deficit that prevents them from downloading until they upload. Since the user has only downloaded unpopular files it can take an unbounded time for the well-meaning user to fine others to upload to. In the worst case the files have declining popularity such that no one ever downloads them again and once again the well-meaning user is forever locked out of the tracker.These are not hypothetical situations. Just try downloading only old episodes of a television show. If you didn't also download a few popular episodes you will have a bad share ratio with nothing to offer to get back in.What we really want is for people to upload when a torrent is unhealthy i.e. when download rates are slow. This is what Bram meant by taking into account the health of the torrent.--Dave

dosirrah
dosirrah

soulxtc.Bram was never sued. Bram claims that he never uploaded copyrighted material. No one has shown that he has.Bram provided a piece of software that sites adopted or reimplemented for illegal file shares as well as legal file shares. It is some of these illegal file sharing sites that have been sued.

the_short1
the_short1

@doshirrah Very well put. Although you are missing one very important aspect to private trackers and ratios. UPLOADING YOUR OWN CONTENTI am a member of a private tracker and i have a ratio of 5-6... with 15gb down 80gb up... with 400 KB down 64KB up max speeds cable... Here are a few points: -download popular torrents and it took foreever to seed back... (you can choose to wait a few days for it to calm down before seeding which lengthen's the life of the torrent also you could limit download to match your upload speeds...) -hard to find old torrents that dont get much traffic (well we dont want you to stop seeding those anyways so for the better that you cant upload back within a day.. - -average health torrents... (works fine) -bad ratio being suspended/banned... (UPLOAD YOUR OWN CONTENT!

political opinion
political opinion

Great article. Ratio cheaters suck, too bad Brad cant lend a hand

pSynrg
pSynrg

Some of the 'private' trackers I use give ratio based on time the file is shared. So even if no one else is nibbling at the torrent you are still trickled some upload credit. The system works very well even on a well fed tracker (100:1 seed/leech ratio). I've just under 1TB downloaded from one of my faves and my ratio is a healthy 3.58. My upload is 1.2Mbps and my download is 15.9Mbps. This system works, why isn't mentioned at all?

ebukh
ebukh

There is a relatively simple way to circumvent the problem of poor ratios when there are a lot of willing uploaders on a torrent and you are the only downloader: wait for a buddy. Declare your intent to download a torrent and wait for at least one person who also has an interest in this torrent to respond. If you then start downloading simultaneously, the protocol will enable a considerable portion of the file to be uploaded from one to the other (in theory 50%, but in practice a lot less, but still sufficient to satisfy most enforced minimum ratios).



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