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Caching Torrent files in DNS
bodin writes "This is a proof of concept version of BitTorrent where the torrent files are transported over DNS. This will of course bog down BIND servers all over the planet. Everyone should be thankful that the files are not sent over DNS."
He's just talking about the .torrent file, which points to a torrent tracker, not the torrent data itself; and DNS works over TCP also.
The tracker does not allocate bandwidth, it just introduces peers to each other.
Plus, I don't see how this is going to put the huge strain on the DNS infrastructure that is implied, apart from the server hosting the torrent's TXT record anyway. Assuming no cached DNS information, I need to perform exactly the same number of DNS queries to resolve foo.domain.com to get a TXT record as I do get pull a tracker file from it. Judging by some of the posts here already some seem to think that the root DNS servers are going to have to handle terabytes of movies files or something, and that just isn't that case.
UNIX? They're not even circumcised! Savages!
255 12,000, 25,000, or I've seen torrents that were several hundred K.
If you read it you have to add a zone so it is not forcing anyone to do anything.
I didn't use the preview button, so get over it!!!!
Mike
I would guess that serving .torrent files is not a problem compared to the bandwidth and CPU used by the tracker. When downloading a file via BitTorrent, you only download the .torrent once but you check in with the tracker every few minutes.
Not only that, but DNS was designed to handle a lot of tiny requests, and a few huge requests. For the many many tiny requests, it uses UDP, and doesnt have to go through the overhead of a full-blown TCP connection. This is what makes it so scalable. If it has to send back more than 512 bytes (for a zone transfer or torrent file), it sets up a TCP connection, but in the case of a zone transfer, it doesnt have to do this very often.
For a typical name query, only two UDP segments are involved, one for the request and one for the response. If you were to request a torrent file, you would need the first three TCP handshaking segments, one to send the request, and then 1 or 2( depending on the machine setup) to send back the torrent file.
Normal DNS query: 2 segments
Torrent file DNS query: 5 or 6 segments
So that takes 2.5-3 times more processing time per request on the DNS server, and that doesnt even take into account the TCP session state.
Your credit card information wants to be free.
Less is more !
I discovered this the other day,
http://www.torrentsearch.org/
basically its a p2p program that downloads the whole database of
You can then search for torrents through the gui. You can then download the
nick
Electronic Music Made Using Linux http://soundcloud.com/polyp
Because sites hosting torrent files for illegal material (which nearly all of it is) will in many cases find themselves shutdown. Through the use of DNS caching it's impossible for any host to shutdown people's access to the tracker immediately.
Lots of postings discuss the load being placed on the DNS servers as lots of mp3's and binaries are transferred through them. Perhaps I am misunderstanding this but surely it's just the .torrent files themselves that are being distributed. The torrent files are just pointers to the trackers which keep a record of the peers who have the files. Distributing the .torrent files probably wouldn't put a massive load on DNS Servers.
The Romans didn't find algebra very challenging, because X was always 10
Star wars episode III would not be downloadable bia dns, only the 200kish .torrent file would be.
I understand he isn't running CD images through this (although someone can), but this could be abbusive to some DNS servers. I run two caching servers for about 45 users and we get around 50K requests in an hour. We need most of the 100 MB allocated to our dnscache to keep the hit ratio where it should be. I can't imagine what some TIER I DNS server might look like if this becomes prevalent.
Sounds like a neat program. Unfortunately, it sounds like a festering mound of virus that would singlehandedly OWN any machine it touches and any unfortunate user too impatient or stupid not to click "AGREE: Totally Hose My Machine". I'm quoting the EULA here, not making this stuff up. Gator's spyware is green with envy:
By accepting this agreement, I certify the following:
4) I understand that by accepting these terms and conditions, this program will be installed on my computer and my web browser home and search page will be changed in order to allow me access.
5) I also acknowledge that a Desktop toolbar will be installed on this system as a stand-alone module and that the Desktop toolbar will update itself from time to time in accordance with the EULA Privacy Policy.
6) I further understand that an accessory tool bar will be added to my web browser which will remain visible as long as the software is installed and agree that I wish to use your search engine for my
web browsers auto search option and default error age.
7) To insure you always have the latest version and for your convenience this software will automatically update itself from time to
time once installed in accordance with this EULA and Privacy Policy.
8) If you decide to change your homepage or search page at a later date this information ?the url? will be sent back to our servers and a pass-through toolbar will be installed at the bottom of your web
browser. This toolbar will remain active as long as this software is installed on your system.
9) I understand that, by accepting these terms and conditions, bookmarks will be added to my system, which may be removed manually or via un-installation of the software.
10) In order for us to keep this software free, from time to time promotional offers from our sponsors will be displayed to you.
11) To prevent your browser from becoming cluttered when our toolbar is installed, any other toolbars you currently have visible will
be deactivated. They can be restored manually through the IE view menu.
12) In order for this software to function properly, If incorrect host-file entries are detected for this software's related domain
names, those entries will be removed.
13) If you wish to uninstall this software you may do so at any time by going to your start menu, Control Panel, Add / Remove Programs, and then selecting this application. Additionally a separate uninstaller may be downloaded from the website the Sponsor Software installs
in your web browser, or you mail email support@lop.com for further assistance.
14) Bookmarking to a page on this server/site whereby this warning page is by-passed shall constitute an implicit acceptance of the
foregoing terms herein set forth.
And it does go on.
I can't imagine what some TIER I DNS server might look like if this becomes prevalent.
. All the root and .com nameservers have to do is provide the cachable referral to domain.com, which they're doing already. It makes no difference to them how many queries the domain.com nameserver receives.
If by "TIER I DNS server" you mean root name server, then the answer is that it would have little effect. The records are stored under names like 0_197_56633ab0d90f43c68ed1b47358eccfe7.domain.com
And as for your caching forwarder: this is going to generate roughly one request for every BT block somebody downloads, typically 256kB. A couple of extra UDP packets are negligible compared to the traffic to actually download the block.
Indeed since most web resources are smaller than 256kB, and many client machines have only a small DNS cache in the browser, it's likely that random web browsing is likely to generate requests at a higher rate. (Admittedly they're more likely to be cache hits.)
Doing this may give you more DNS misses but if you're downloading gigabytes of data the cost of the misses will be negligible.
Assume a DNS RR takes (generously) 1kB of disk or traffic. The queries to do this are still less than 0.5% of the traffic generated by the downloads themselves. If you allocated another 1GB of disk (about $1 at today's rates) then you could cache the tracker information for 256GB of BitTorrent downloads, which ought to keep your users supplied with Japanese tentacle porn for at least a few days.
Torrentsearch installs a LOT of spyware (more than it admits) - I recommend running it on a PTP bitch box rather than your regular machine.
I've seen torrent files that are in the area of 10-100k. Sometimes larger.