DOKK / manpages / debian 11 / nbdkit / nbdkit-torrent-plugin.1.en
nbdkit-torrent-plugin(1) NBDKIT nbdkit-torrent-plugin(1)

nbdkit-torrent-plugin - serve a BitTorrent file or magnet link over NBD

 nbdkit torrent FILE.torrent|'magnet:?xt=urn:...'
                [file=DISK.iso] [cache=DIR] ...

"nbdkit-torrent-plugin" is an nbdkit(1) plugin which lets you serve a single file from within a torrent read-only over NBD. The torrent to download can be a local FILE.torrent file, or a magnet link.

A single torrent contains a collection of files, and by default this plugin serves the largest file within the torrent. For operating system installers this is usually the large ISO file and ignores other small files like READMEs. You can also select a particular file by name to serve.

If you want to turn a file hosted on a web server into an NBD export use nbdkit-curl-plugin(1) instead. If you have a local ISO you can simply serve it using nbdkit-file-plugin(1). If you want to turn a local directory into an ISO use nbdkit-iso-plugin(1).

This plugin implements a full-featured BitTorrent client. BitTorrent clients form a peer-to-peer (p2p) network and upload the file to other clients as well as downloading.

By default the plugin will cache the downloaded torrent into $TMPDIR, potentially consuming a lot of disk space. See the "cache=DIR" parameter for how to control this.

By default the plugin will consume all available network bandwidth in both download and upload directions. To limit it, set "download-rate-limit" and "upload-rate-limit" appropriately.

Choose the right URL from https://torrent.fedoraproject.org/:

 url=https://torrent.fedoraproject.org/torrents/Fedora-Server-dvd-x86_64-32.torrent
 wget $url
 nbdkit -U - torrent Fedora-Server-*.torrent \
        --run 'qemu-system-x86_64 -m 2048 -cdrom $nbd -boot d'

Choose the right URL from https://www.debian.org/CD/torrent-cd/:

 url=https://cdimage.debian.org/debian-cd/current/amd64/bt-dvd/debian-10.4.0-amd64-DVD-1.iso.torrent
 wget $url
 nbdkit -U - torrent debian-*.torrent \
        --run 'qemu-system-x86_64 -m 2048 -cdrom $nbd -boot d'

Set a directory which will be used to store the partially downloaded torrent between runs.

This parameter is optional. If not given then the plugin will create a randomly named temporary directory under $TMPDIR, and will attempt to ensure it is cleaned up on exit (thus unless you set "cache", no state is saved between runs and the whole torrent must be downloaded each time).

Set limit on number of connections to other peers that this client will open (default 200).
Set the download rate limit in bits per second. Usual abbreviations can be used such as "download-rate-limit=1M" for 1 megabit per second. 0 means unlimited, which is the default.
Select the file from within the torrent to serve.

This parameter is optional. If not specified then the plugin searches the torrent for the largest file and serves that. This is usually the right thing to do for operating system installers and similar because it serves the large .iso file and ignores other files like READMEs.

The parameter is actually a path relative to the root directory of the torrent, so if the torrent contains subdirectories you may need to use a path like "file=SUBDIR/DISK". To list all the files within the torrent try running:

 $ nbdkit -fv -U - torrent file.torrent

and examining the debug output. As an alternative you can use standard BitTorrent tools, eg:

 $ transmission-show file.torrent
Listening ports that are opened for accepting incoming connections. The parameter is a comma-separated list of "IP-address:port".
Controls which IP address outgoing TCP connections are bound to. The parameter is a comma-separated list of IP addresses.
[torrent=]FILE.torrent
Specify a local torrent file.
[torrent=]magnet:?xt=urn:...
Specify a magnet link.

"torrent=" is a magic config key and may be omitted in most cases. See "Magic parameters" in nbdkit(1).

Set the upload rate limit in bits per second. Usual abbreviations can be used such as "upload-rate-limit=1M" for 1 megabit per second. 0 means unlimited, which is the default.
Set the user-agent. The recommended format is "client-name/client-version".

"TMPDIR"
This directory is used to cache the downloaded torrent file (or /var/tmp if not set). See also the "cache=DIR" parameter above.

$plugindir/nbdkit-torrent-plugin.so
The plugin.

Use "nbdkit --dump-config" to find the location of $plugindir.

"nbdkit-torrent-plugin" first appeared in nbdkit 1.22.

nbdkit(1), nbdkit-plugin(3), nbdkit-curl-plugin(1), nbdkit-file-plugin(1), nbdkit-iso-plugin(1), nbdkit-readahead-filter(1), transmission-show(1), https://en.wikipedia.org/wiki/BitTorrent, http://libtorrent.org/.

Richard W.M. Jones

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2021-01-20 nbdkit-1.24.1