Interesting Links for 12-02-2012

[andrewducker]

• Can a court order stop a torrent file?
  Of course it can't. And much though I feel sympathy for the young lady, she hasn't got a hope in hell of fixing this one.
  (tags: censorship torrents privacy law nudity )
• Putting pension tax breaks for the rich under the scrutiny
  (tags: politics money pensions libdem )
• Madonna’s NFL Satanic Ritual disguised in

Comments

[steer]

Actually the issues with possible disruption to torrent files is why piratebay and others are moving to magnet files. It's hard to block a torrent file sure but not enough to qualify as impossible. Hence the current generation bittorrent stuff uses magnet links instead.

[andrewducker]

And, apparently are working on distributed searching too. For that awesome eMule experience.

[steer]

Yes -- I've had some minor involvement in that work myself. The problems difficult because you have to have some way of stopping people corrupting the search by adding "false" matches. (Imagine the problem of designing google without some central authority to weed out the spam.)

[andrewducker]

I notice that the latest version of uTorrent is asking me what the quality of the torrent was like. I assume that's part of one approach to this problem!

[steer]

To my shame I don't know the answer to that one and I'm actually a little hazy about how magnet links work -- I mean I know the details of distributed hash tables but not the particulars of how magnet connects you to them.

[andrewducker]

Well, looking at a sample one:
magnet:?xt=urn:btih:2d96dd594a37acd2fb212cddb8e44dfe7a658044&dn=The+Name+Goes+Here&tr=http%3A%2F%2Ftracker.publicbt.com%2Fannounce

I've seen multiple trackers appended at the end of the URL, and that the dn specified name isn't actually important, as it's replaced by the actual name of the file once a download starts.

So presumably the only vital bit is the hash, which is used by DHT to find other people with the same file. Trackers obviously help speed things up, of course.

And looking at the wikipedia entry, it seems that they originated with freenet and eDonkey, which makes perfect sense.

[steer]

I can't bloody believe I fell for that! Rickrolled over a magnet link! You bastard!

I take my hat off to you sir.

:-)

Yes... the torrent, name etc are not necessary, just the hash and some way to contact the DHT system. I don't know how it make the initial DHT contact though -- a handful of permanent nodes the client knows of perhaps.

[andrewducker]

I was trying to work out what the best data to use as an example was, and that seemed like the funniest :->

I'm not sure how initial DHT contact is made. eMule always needed a few IP addresses to get started the first time you run it. uTorrent presumably uses ones from previous connections it's made.

Aaah - and apparently router.utorrent.com and router.bittorrent.com are "Known Good Nodes" or somesuch. There's a bit of discussion here:
http://forum.utorrent.com/viewtopic.php?id=56618

[undeadbydawn]

there's also the fact that magnets take up rather a lot less server space. The switch will lighten the load on TBP bandwidth significantly. They managed to fit the entire magnet database into roughly 90megs

[steer]

Yup... plus the legal issues are even more obfuscated now. The pirate bay doesn't tell you who has the files it tells you some information which will enable you to recognise and request the files.