Last updated on September 5, 2020 by Gabriel Cánepa
If you are the type of person who uses several devices to work online, I'm sure you must be using, or at least wishing to use, a method for syncing files and directories among those devices.
BitTorrent Sync, also known as
btsync for short, and now renamed to Resilio, is a cross-platform sync tool (freeware) which is powered by BitTorrent, the famous protocol for peer-to-peer (P2P) file sharing. Unlike classic BitTorrent clients, however,
btsync encrypts traffic and grants access to shared files based on auto-generated keys across different operating system and device types.
More specifically, when you add files or folder to
btsync as shareable, corresponding read/write keys (so-called secret codes) are created. These keys are then shared among different devices via HTTPS links, emails, QR codes, etc. Once two devices are paired via a key, the linked content can be synced directly between them. There is no file size limit, and transfer speeds are never throttled unless you explicitly say so. You will be able to create accounts inside
btsync, under which you can create and manage keys and files to share via web interface.
BitTorrent Sync is available on multiple operating systems including Linux, MacOS X, Windows, as well as Android and iOS. In this tutorial, I will show you how to use BitTorrent Sync to sync files between a Linux box (a home server), and a Windows machine (a work laptop).
BitTorrent Sync is available for download from the project's website. I assume that the Windows version of BiTorrent Sync is installed on a Windows laptop, which can be done very easily. I will focus on installing and configuring it on the Linux server.
In the download page, choose your architecture, right click on the corresponding link, choose Copy link location (or similar, depending on your browser), and paste the link to
wget in your terminal, as follows:
# wget https://download-cdn.resilio.com/stable/linux-x64/resilio-sync_x64.tar.gz # tar -xf resilio-sync_x64.tar.gz # cp rslsync /usr/local/bin # ln -s /usr/local/bin/rslsync /usr/local/bin/btsync
# wget https://download-cdn.resilio.com/stable/linux-i386/resilio-sync_i386.tar.gz # tar -xf resilio-sync_i386.tar.gz # cp rslsync /usr/local/bin # ln -s /usr/local/bin/rslsync /usr/local/bin/btsync
You can now either add
/usr/local/bin/btsync to your
PATH environment variable.
or run the
btsync binary right from that folder. We'll go with the first option as it requires less typing and is easier to remember.
Btsync comes with a built-in web server which is used as the management interface for BitTorrent Sync. To be able to access the web interface, you need to create a configuration file. You can do that with the following command:
# btsync --dump-sample-config > btsync.config
Then edit the btsync.config file (webui section) with your preferred text editor, as follows:
"listen" : "0.0.0.0:8888", "login" : "yourusername", "password" : "yourpassword"
You can choose any username and password.
Feel free to check the README file in
/usr/local/bin/btsync directory if you want to tweak the configuration further, but this will do for now.
As system administrators we believe in logs! So before we launch
btsync, we will create a log file for
# touch /var/log/btsync.log
Finally it's time to start
# btsync --config /usr/local/bin/btsync/btsync.config --log /var/log/btsync.log
Now point your web browser to the IP address of the Linux server and the port where
btsync is listening on (
192.168.0.15:8888 in my case), and agree to the privacy policies, terms, and EULA:
and you will be taken to the home page of your
Add a folder, and choose a directory in your file system that you want to share. In our example, we will use
That's enough by now. Please install BitTorrent Sync on your Windows machine (or another Linux box, if you want) before proceeding.
The following screencast shows how to sync an existing folder in a Windows 8 machine [192.168.0.106]. After adding the desired folder, get its key, and add it in your Linux installation via the
Enter a key or link menu (as shown in the previous image), and the sync will start:
Now repeat the process for other computers or devices; selecting a folder or files to share, and importing the corresponding key(s) in your "central"
btsync installation via the web interface on your Linux server.
You will notice that the synced files in the screencast were created in the
/btsync directory belonging to user and group
root. That is because we launched BitTorrent Sync manually as the superuser. However, under normal circumstances, you will want to have BitTorrent Sync start on boot and running as a non-privileged user (
www-data or other special account created for that purpose,
btsync user for example).
To do so, create a user called
btsync, and add the following stanza to the
/etc/rc.local file (before the exit 0 line):
$ sudo -u btsync /usr/local/bin/btsync/btsync --config /usr/local/bin/btsync/btsync.config --log /var/log/btsync.log
Finally, create the pid file:
# touch /usr/local/bin/btsync/.sync//sync.pid
and change the ownership of
# chown -R btsync:root /usr/local/bin/btsync
Now reboot and verify that
btsync is running as the intended user:
Based on your chosen distribution, you may find other ways to enable
btsync to start on boot. In this tutorial I chose the
rc.local approach since it's distribution-agnostic.
As you can see, BitTorrent Sync is almost like server-less Dropbox for you. I said almost because of this: When you sync between devices on the same local network, sync happens directly between two devices. However, if you try to sync across different networks, and the devices to be paired are behind restrictive firewalls, there is a chance that the sync traffic goes through a third-party relay server operated by BitTorrent. While they claim that the traffic is AES-encrypted, you may still not want this to happen. For your privacy, be sure to turn off relay/tracker server options in every folder that you are sharing.
Hope it helps! Happy syncing!