[vox-tech] bittorrent

[Jeff Newmiller]

On Thu, 4 Dec 2003, Peter Jay Salzman wrote:

> ok, i've downloaded bittorrent on debian/sarge.  now what?
> 
> i've read some material, and here's what i think i know:
> 
> 1. to get the best download speeds, i'll need to poke holes in
>    tcp/6881 through tcp/6889.

Actually, poking holes enables uploads... which in turn prompts recipients
of your largesse to give you higher priority... leading to generally
faster downloads.

I only poke one hole at 6881, because I only do one file at a time.  If
you want to be able to do more simultaneous downlads, then poke more
holes.  In my case, the download usually sucks up most of my bandwidth, so
running more than one instance at a time doesn't really make much sense.

> 2. i need to open a web browser, find a bittorrent link, and click on
>    it, which will open up the bittorrent helper application and engage
>    in the download of whatever the file points to.

I didn't bother to enable the helper application... I just invoke it
at the command line.

In my case, I have a NATing firewall, so I invoke it as

  $ btdownloadgui.py --ip my.external.ip.address 'torrent_url'

> that's what i think i know.  how accurate is this?

Accurate enough to get by, I suppose.

> how does one find .bittorrent links?

Google?

There are some sites that specialize in particular types of
files... depends what you are looking for.  Slashdot sometimes posts
links.  They just represent a specialized download protocol.

> does anyone have a bittorrent testfile handy to download some very small
> text file in a 'Hello World' fashion?

Seems not much point to this, since BT can take 5 or 10 MB to get into the
swing of things.  If you really want to download a small file,
www.toriyamaworld.com regularly distributes translated manga scans (2-6MB)
using BT.

Some additional notes:

a) Sarge doesn't have the newest bittorrent...  but I don't know that this
is so terrible.  The newer version (3.3) is supposed to be a little more
efficient, and it reports accumulated upload and download amounts which
gives you an idea of how much you have contributed back to the torrent,
but the older version still works.

b) Don't be surprised when the whole file appears on your hard disk
immediately.  BT downloads random chunks, so it has to do this... but the
file won't be usable until BT says the whole thing is downloaded.

c) You can stop and restart your download at will. (Restarting is exactly
the same as starting.) BT will automatically pick up where it left off.  
Corollary: you can start a BT download on a file you already have
completed if you want to help upload... this is known as seeding.

d) Note the number of seeds on a download before you begin (a nice torrent
manager will set up a tracker to provide you with these statistics)... if
you have half the file and the last seed disconnects, your download will
never complete.  Ergo, communicating with someone who _has_ downloaded the
whole file and asking them to seed for you may be necessary if a torrent
is no longer popular.

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