From Knoppix Documentation Wiki
Bittorrent is a swarming downloading method which allows for large files to be distributed far quicker and more bandwidth efficiently than simply many users downloading from one server. When you use a torrent to download a file, you are also contributing to the files distribution. And you are able to download from many soures providing the file download, not just one mirror. As you receive sections of the file (which are individually verified) you will also start to send those sections of the file to other users who need them, similarly you will be receving the file from numerous other users. The more people who are attempting to download a file, the quicker it will spread.
What does all of this have to do with Knoppix? Well Knoppix is large download (about 700MB for the CD version and over 3 Gig for the DVD version) and can have extremely large numbers of people looking to download it in a short space of time (when a major new version is released). Due to the load this places on the server hosting the download, Knoppix can be slow to get around onto the network of mirrors.
Knoppix 3.4 was different, in fact it was released first via Bittorrent at http://torrent.unix-ag.uni-kl.de/ . Things weren't completely smooth sailing at first as the demand was staggering but since then the setup has been refined and seems to have no problems coping with the loads thrown at it. Recent versions of Knoppix released on BitTorrent feeds have been seen to download much faster than available from the mirrors, often at speeds as high as the user's download pipe will permit.
To top it all off, you will often see mention of people having problems with Knoppix where ultimately it comes down to a broken download. If you don't have the bandwidth to not care about having to redownload a copy of Knoppix if something goes funny (and if you do can you give some to the rest of us please), then Bittorrent is the answer. If Bittorrent is happy, you can be sure the file you have is identical to the original, for modem users who may have to reconnect many times to finish the download, this is a godsend (one crash could destroy the past 30 hours downloading by http/ftp, but bittorrent will fix the download without having to duplicate any significant amount of downloading).
Now for the downside, in certain circumstances you just won't be able to use Bittorrent. If you are behind a firewall you do not control you will either not be able to use Bittorrent at all or your download speeds will be appalling (for example, downloading at the office). If you can control the firewall (for example, it is part of your home DSL/cable router), then you should be able to open Bittorrent traffic to your computer and get maximimum download speeds. It is very important to open these ports in your firewall, otherwise you will stll be able to download but will not get good download speeds.
The official Bittorrent Client is available from http://bittorrent.com/download.html though personally I prefer Bit Tornado (primarily as it has a nice pause button for when you need to do something else quickly). While this was a valid concern for versions 3.x of BitTorrent, version 4.x releases now have both a handy pause button and a very nice adjustable slide control to adjust the maximum bandwidth that you are willing to allow BitTorrent to use. This can be a very handy feature as it allows BitTorrent to still share what you have downloaded with other users but not swamp your upload capacity (which could affect your other Internet use and in some cases even slow your download speed by not letting you send download requests fast enough). Setting this control just a few K bytes less than you maximum upload speed gives great results.
If you have broadband and want to "give something back" to the community, leave your BitTorrent client up and running afer your download has finished. You will be using available bandwidth that would otherwise go to waste to help others get their copy of Knoppix. You can even shut the client down and restart it later (such as when you go to bed) and it will still seed the files that you have downloaded. BitTorrent also allows for resuming a download, so if you have to stop downloading for any reason you can restart you client later and it will pick up where it left off and complete your download for you while it continues to seed what you aleady have.
BitTorrent is now the most widely used proptcol on the Internet (behind only TCP/IP itself). If you are going to be downloading CD and DVD size files like Knoppix, it will be extremely important to you to take a couple of minutes and learn to use BitTorrent. And once you have done it, a couple of minutes is all it takes (Personal experience shows it can be set installed complete with port forwarding in less than one minute).
If you are using the CD-based Knoppix right now, the Java-based Azureus client can be installed to a hard disk or USB key and it will work properly.
Because the bittorrent clients do not offer a search function, many web sites with torrent search engines arised. Throughput.de is one of those.
Some tips on using BitTorrent:
If You plan on downloading the DVD version of Knoppix, be sure to upgrade to a current version of BitTorrent. Some old versions have problems with files over 2 gig in size.
Make sure that you have the Knoppix ports 6881-6899 forwarded to your BitTorrent system in your router. Most current routers will recognize activity on a "trigger port" and automatically forward a range of ports to which ever local IP address they see activity of the trigger port coming from. This can be a handy way to forward ports to the computer that you use for BitTorrent. You can configure a router so that BitTorrent can be used on more than one system at the same time, but this involves more detailed port settings and is not useful for most home users. Also be sure that any software filewall passes this port range for BitTorrent. If you fail to do these steps BitTorrent may still seem to work, but will likely run extremely slow.
You can shut down BitTorrent and stll restart it later to help share the bandwidth that you are paying for anyway to redistribute Knoppix. BitTorrent will check your file and then make it available to other users. May users "seed" the Knoppix files after downloading them, often when they go to sleep or leave the house. Restarting does take some time to recheck the files; current versions of BitTorrent have a handy "pause" button that will let you halt sharing if you need your computer or connection for other things. You can then restart without needing to do another check (which does take some time on DVD sized files) by turning off pause. Current BitTorrent versions also have a handy slider to control upload bandwidth. If you need to use you connection for other high demand things, it is often better to lower the bandwidth BitTorrent will use to upload files with the slider than to completely shut it down or to pause it.