Resilio Sync

Resilio Sync (formerly: BitTorrent Sync or BTSync) is a proprietary file sharing system that relies on the BitTorrent Peer-to-peer (P2P) protocol.

Instead of having a central server which archives every file, it uses peer-to-peer connections between the devices themselves therefore there is no limit on data storage and/or transfer speed. The user's data is exclusively stored on the devices with which the user chose to be in sync with, hence it is required to have at least two user devices, or "nodes" to be online. If many devices are connected simultaneously, files are shared between them in a mesh networking topology.

All traffic between devices is encrypted with AES-128 in counter mode, using a unique session key. This key is derived from a 'secret' which itself is a random 21 Byte key Base32-encoded. By handing over the 'secret', files and folders can be shared with other users. When a device adds a folder for synchronization, a secret is generated. From now on, every device that wants to synchronize that folder must know the secret key. The synchronization has no speed or size limits, as long as both devices have enough disk space.

Installation

rslsync^AUR can be installed from the AUR. The package includes systemd service definitions for managing the rslsync daemon. This package creates a default /etc/rslsync.conf for system/root operation. Make the desired changes (e.g. login id and password) to those files prior to enabling rslsync.service.

Alternatively, the bare 'tar.gz' packaged executable can be downloaded from the official website. The rest of this guide assumes that you are using the rslsync AUR package.

Usage

The Linux client of Resilio Sync does not use a typical GUI, instead it sets up a WebUI server accessible at localhost:8888. Shared folders can also be configured statically in a configuration file, but doing so disables the WebGUI.

Once installed, you will first need to create a configuration file at ~/.config/rslsync/rslsync.conf, see #Configuration. You will also need to create the storage_path directory. When that is done, start and (if you want it to start on boot) start/enable the user service rslsync (i.e., with the --user flag).

The service will run as the user invoking the command. Note that the above command is not run as root: doing so may lead to a cryptic error stating that D-Bus has refused the connection.

Note:

It is important to make sure that when rslsync is run as the user, the rslsync.conf file and directory where the rslsync.pid file will be located have the correct user permissions, i.e. are owned by the user invoking the command. Failure to do so will prevent the service from running. If the user permissions are correct but rslsync still fails to run after being enabled, restart your system.
If running rslsync on a headless server, enable lingering to start rslsync and keep it running outside user sessions: Systemd/User#Automatic start-up of systemd user instances.

You can also run it as the rslsync.service system user (without the --user flag).

Configuration for this user is located at /etc/rslsync.conf, and metadata is saved in /var/lib/rslsync/ by default. You should review the configuration settings especially user and password, see below.

Configuration

A sample configuration file can be created using:

# rslsync --dump-sample-config > ~/.config/rslsync/rslsync.conf

You will probably want to change some of the settings, including:

device_name
storage_path
webui/login
webui/password

Note:

The rslsync executable does not create the storage_path directory if it does not exist, you will have to do this manually or use #Automatic configuration file creation.
The storage_path setting defines where metadata will be saved, not the synced files themselves. Where synced files are saved is configured on a per-folder basis in the WebGUI.
The configuration option webui/password_hash_unified is calculated with webui/password_hash_salt_unified prepended, if any salt is used at all.

Automatic configuration file creation

The rslsync^AUR package provides a systemd user service called rslsync.service which, if enabled, triggers when a user's rslsync_user.service starts. Then a configuration file with default values will be created if it does not already exist.

Note: If the configuration file was generated by rslsync^AUR it will be configured with a different port. Rather than 8888, the port for the user's instance of rslsync will be 7889 + $UID. If your $UID is "1000", the port will be 8889.

The install script enables the service for all users by default. Although defeating most of its purpose, rslsync.service can be disabled.

Individual users can then enable the rslsync_user.service user unit.

rslsync_user.service creates ~/.config/rslsync/rslsync.conf if it does not exist, and guesses some default values of the settings:

device_name: $USER@$HOSTNAME
storage_path: ~/.rlsync
webui/login: $USER/password

The script also creates the storage_path directory set in the configuration file if it does not exist. This is done independently from the creation of the configuration file.

Troubleshooting

Missing storage path

If you start the service but cannot reach the WebUI, check the unit status for the system-wide instance or the user unit.

A common error is Storage path specified in config file does not exist.. This is easily fixed by mkdir ~/.rslsync, or whatever your storage_path is set to.

Ignore some files/folders synchronization

If you don’t want Resilio Sync to track some files in your sync folder, please use IgnoreList. IgnoreList is located in hidden .sync folder.

IgnoreList is a UTF-8 encoded .txt file that allows you to specify single files, paths or rules for ignoring during the synchronization job. Each line of the IgnoreList file represents a separate rule. All the files that fall under the ignore filter are not indexed and not counted in the "Size" column in Sync main view.

It supports '?' and '*' wildcard symbols.

Note that IgnoreList is applied only to the folder where it is contained and will not work with the files that have already been synced. If you add indexed files to IgnoreList, they will be deleted on other syncing devices. In order to avoid this:

Remove the folder from sync on all the devices.
Modify IgnoreList file on all of them so that it contains same info.
Re-add the modified folders.

For further details, please refer to Ignoring files in Sync (IgnoreList)

ARM alignment error

Add the line w /proc/cpu/alignment - - - - 2 to /etc/tmpfiles.d/rslsync.conf. (You need to create the file).
Note that this may lead to performance degradation.

Error while loading shared libraries: libcrypt.so.1

If you receive the error message error while loading shared libraries: libcrypt.so.1 starting rslsync with the binary or as a service, install the package libxcrypt-compat.