Libtorrent

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Note: This page describes the BitTorrent library "libtorrent-rasterbar" by Rasterbar Software (Arvid Norberg) but not the similarly named BitTorrent library "LibTorrent" by Rakshasa.

libtorrent-rasterbar is a BitTorrent library written in C++. It is used by popular clients, such as qBittorrent (Qt) and Deluge (Python).

I2P Support

The I2P support is available through the SAMv3 bridge in libtorrent. It was broken until late 2022 after a thread on zzz.i2p, resulting in several patches being merged upstream.

Issues

Currently (early 2023), the peer count shows the right numbers, but the peer list (both in libtorrent's client_test and qBittorrent) shows only one peer with an IP address of "0.0.0.0:0".
(client_test shows multiple 0.0.0.0's, while qBittorrent shows only one.)

Examples

libtorrent

For libtorrent's client_test program, the following command can be used to leech/seed a magnet through I2P (by Vort):

examples/client_test --enable_dht=false --proxy_type=i2p_proxy --i2p_hostname=127.0.0.1 --i2p_port=7656 'magnet:?xt=urn:btih:889401025a1c16bbf9d8001ae157679507a87feb&dn=I2P%2B+Universal+Installer+2.1.0%2B&tr=http://tracker2.postman.i2p/announce.php'

You can press 'h' within client_test to see the available options.

qBittorrent

For qBittorrent, I2P support has been merged with qBittorrent version 4.6 (although still considered experimental). It can now be turned on in Settings->Connection. Tunnel length and quantity can be tuned in Advanced->libtorrent Section.

(Note: One might also want to enable Anonymous Mode. (Settings->BitTorrent->Enable anonymous mode))

Before I2P support was merged

Before that (until the I2P support is added), one needed to build using Jiigen's fork.

Make sure the installed libtorrent-rasterbar library includes the I2P-fix commit. Building/Installing from source is recommended until the release with the fix is tagged and becomes available on most distros.

git clone https://github.com/jiigen/qbittorrent -b i2p-support jiigen_qbit
cd jiigen_qbit
mkdir build
cd build
cmake ..
make
sudo make install

And within the Settings->Connection->Proxy, one needs to set "Proxy Type" to I2P, the host/port to SAM bridge's host/port, and needs to tick "proxy for peer connections/host lookups".

External links

• https://libtorrent.org - home page
• https://github.com/arvidn/libtorrent - GitHub repository
• https://github.com/qBittorrent/qbittorrent - qBittorrent's GitHub repository