Slashdot Mirror
Researchers Create Selfish BitTorrent Client
An anonymous reader writes "Researchers from the computer science department at the University of Washington have released BitTyrant, a new BitTorrent client that is designed to improve download performance via strategic selection of peers and upload rates. Their results call into question the effectiveness of BitTorrent's tit-for-tat reciprocation strategy which was designed to discourage selfish users. Clients are available for Windows, OS X, and Linux."
internet bandwidth usage has just gone up by 300% at the University of Washington... Scientists are baffled and blame global warming.
It looks like all it's doing is trying to allocate its uploads more efficiently. Which, assuming it works, should improve things overall, and (if it works) may even get adopted into the official protocol.
I am trolling
If you bothered to RTFA, you'd realise selfish!=bad.
Yes, problem is it's similar to changing UserAgent tag in IE or FireFox. Too easy. It's not very viable solution.
"an experienced, industrious, ambitious, and often, quite often, picturesque liar" - Mark Twain
No offense, but that can be spoofed quite easily. Make it say BitTorrent, uTorrent, or Azureus and then what? As the co-founder of Azureus this has always been a problem and threat to the BT protocol. The best clients can do is make sure packets are being spread once they're sent to another person. The algorithm works like this --send a "rare" packet, watch to make sure another client shows up with that rare packet in X time. Clients should send their rarest packets first, to keep the swarm happy. So if the packet doesn't show up, you've got a leech and your drop him in the Queue. TdC
Selfish selection of peers can lead to cliques of clients on the same network. Tit-for-tat has been proven as a highly effective strategy in games resembling the iterated prisoner's dilemna, but it can be defeated when a large enough group of of agents cooperate. This link has more.
RTFA. They didn't create a client that is "selfish" by trying to avoid uploading. They created a client that is selfish by first allocating more upload capacity to other clients that will send them more when they upload more, and only allocate the remaining upload capacity to clients where benefits from increased uploading are not certain. If you read their paper, they regularly bring up the effects of this on the entire network and they don't know if it's good, bad, or has any effect on the network (and not for a lack of trying)
Some folks at ETH Zurich took it one step further, and wrote a client - BitThief - that doesn't upload and yet still can download as fast as a regular client. This is especially valuable in countries that define copyright violation to be the uploading of content.
Did you actually read the paper?
They are looking at improving download time for that user and the overall swarm by the use of their algorithm.
The idea being that you share all the upload space you have - but you do it in such a way as to maximise what you can download in the same amount of time.
This in turn means that when you have finished downloading the file the number of copies within the swarm will have increased - also those that shared with you more will have been able to download quicker themselves.
A client like this will penalise selfish or greedy uploaders far more than the normal client as it rewards those that give back.
Give a leach a block and he will have downloaded that block, teach a leach to seed and he shall have blocks for the rest of his life.
$_="Slashdotter";$syn="OTT";s;..;;;sub _{print shift||$_};s!ash!Perl !;s=$syn=ack=i;tr+LLEd+BLAH+;_"Just Another ";_
Actually this client would likely be favoured by the private tracker sites.
The private tracker already gives you plenty of incentive to make sure your ratio is >1 - even asside from basic morals.
The design of this client means those with higher speed uploads available will complete sooner, and thus you will end up with more high speed seeders.
Seeders who since they are members of private trackers are probably going to stick around until ratio >1
True I admit on piblic trackers something like this may not be as helpful or beneficial, but you can't have everything.
$_="Slashdotter";$syn="OTT";s;..;;;sub _{print shift||$_};s!ash!Perl !;s=$syn=ack=i;tr+LLEd+BLAH+;_"Just Another ";_
The anti-leech technology of the bittorrent protocol remains effective. Those ranting about this just haven't bothered to read... This client (despite the unfortunate name) is just smarter about how to use upload bandwidth, in an async world.
In fact, I would say this is an IMPROVEMENT in some ways over bittorrent's default behavior, as it will dedicate more of your outgoing bandwidth to higher-speed peers. They, presumably, can then serve up more data to others than a low-speed peer reasonably could.
Instead of being the end of bittorrent, this could really improve the health of the P2P network, increasing speeds and decreasing download times for everyone (not only those using this program).
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
BitTyrant (read the paper) [i]follows the protocol[/i].
From any other peer, you can't tell whether someone is using the BitTyrant bandwidth selection strategy or the default allocatino strategy, and user agent is, of course, meaningless.
Test your net with Netalyzr
Awesome! If everyone used that client, the MPAA/RIAA wouldn't have a leg to stand on.
Not rare, it's extremely common on private sites with specialized material. I've had trouble raising my ratio above 0.85 on DIME, in spite of having 250KB/s upload. It's annoying, but there's not much you can do about it.
LOAD "SIG",8,1
I'd love to give it a spin, but at 2kbs download for the client installer I'll be here all night. Maybe I can find a torrent for it for a faster download...oh the irony.
And now what? You didn't do something really, really foolish, like believing the Slashdot headline before RTFAing, did you? Silly hobbit.
If you were blocking sigs, you wouldn't have to read this.
From the 'article' (really just a brief overview), it's clear that it will generally at present improve performance for the BitTyrant user; it will also statistically improve performance for any peer with substantial spare upload capacity, regardless of client used.
B itTyrant.pdf [cs.washington.edu] goes into considerably more detail, and is well worth reading if you have a nodding acquaintance with the BT protocol and elementary game theory.
This paper http://www.cs.washington.edu/homes/piatek/papers/
It probably will initially hurt performance for users with saturated upload capacity who cannot contribute any more to the swarm than they are at present.
It's not at all clear that this is a bad thing, even if everyone switched to BTyrant. A lot could come down to the social behavior of Tyrant users once they become seeders, for example. If a Tyrant keeps a torrent active as long as s/he presently does, it would clearly be an improvement. For those who say "well a tyrant user may not even seed to 1.0"; fine; that Tyrant user won't really benefit much from the protocol.
Holmwood
Gotta say, these speeds are really impressive. Azureus 2.5 would download at about 35kb/s, while the same torrent on BitTyrant is 400kb/s. I use a private torrent network, so I'll have to make up for the ratio afterwards; but still, it's great to get things so quickly.
Emule has a system like this, and it basically slows everything down in the name of fair sharing. It takes absolutely forever to start downloads, since you're stuck in a vicious "chicken and egg" circle of "I can't upload anything to download" and "I can't download anything to upload".
As it stands, Bittorrent is how the Edonkey protocol used to be before ratio systems were added to the clients; Fast. After Edonkey started adding anti-leech systems to the clients, the speed went into the toilet, and the queues started skyrocketing.
I suspect that if this catches on, you can kiss 300kb's downloads goodbye.
In Soviet Russia, Trojan exploits YOU!
Most likely it's misconfiguration on your part. Specifically, you're behind router doing network address translation or a firewall that is blocking inbound connections on the key ports.
In order for you to get good download performance you have to upload at a reasonable rate (at least with clients other than BitTyrant). To do that, you have to make it possible for other peers to connect to your machine.
Odds are it's a NAT problem. See if you can configure your router to forward incoming TCP and UDP packets on ports 6881-6889 to your computer. Even easier, if your router supports Universal Plug-n-Play (UPNP), get a client that does (like Azureus) and tell it to use UPNP. That will allow the client to automatically tell the router how to configure itself.
Once you get the network configuration right, you also need to make sure your upstream connections are choking your downloads, as can happen with braindead ISPs (i.e. pretty much all phone and cable companies). Use your client's upload rate configuration parameter and set it to a little less than the upstream rate that your connection provides. I have 384kbps upload rate and I find I can send as much as 35KBps without trouble.
I have a 5Mbps connection, and I routinely get 500KBps on popular torrents.
Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.