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Syncthing is an open-source file synchronization client/server application, written in Go, implementing its own, equally free Block Exchange Protocol. All transit communications between syncthing nodes are encrypted, and all nodes are uniquely identified with cryptographic certificates.


Syncthing can be installed with the syncthing or the syncthing-gtk package. This latter includes additional features such as synchronization by inotify, desktop notifications and integration with Nautilus, Nemo and Caja.

After installing, you can either run the syncthing binary manually from a terminal, or start it as a systemd/User instance using the provided syncthing.service. Alternatively, you can utilize the syncthing@.service if you require it to run without an active user session.

The systemd services need to be started for a specific user in any case. See Autostart-syncthing with systemd for detailed information on the services.

When syncthing is started, a web interface will be provided by default on localhost port 8384. If you started syncthing manually, it should open the admin page in your browser.

Note: In syncthing releases before 0.11 (or when you have updated from 0.10) the web interface is available at port 8080. Since port 8080 often conflicts with web development utilities the default port has been changed to port 8384 ('ST' in ASCII). Custom port number can be configured under "GUI Listen Addresses" in the settings, configuration from versions prior to 0.11 were not adjusted automatically.
Tip: You can run multiple copies of syncthing, but only one instance per user as syncthing locks the database to it. Check logs for errors related to locked database.


After installation Syncthing already has a proper start-up configuration. You may now add new servers and/or folders by visiting the web interface. For detailed instructions on how to set up a simple network, read Syncthing's getting started.

After a successful first start, it will create the default repository at ~/Sync. You can see this in the web admin interface. On the right is the list of nodes you have added. On the left is the list of repositories, which are folders you can choose to share with other nodes.

To add another node, click "Add Node" underneath the list of nodes. You will be prompted for their Node ID (which can be found on the other machine by clicking Edit > Show ID) as well as a short name and the address. If you specify "dynamic" for the address, the syncthing announce server will be used to automatically exchange addresses between nodes. If you want to know more about Node IDs, including the cryptographic implications, you can read the appropriate Syncthing documentation page.

After saving the configuration, you will be prompted to restart the syncthing server, and once restarted, the changes will be applied.

Next, you can either change the configuration of the default node (click its name and then Edit), or create a new one to share data with. Simply tick the node you wish to share the data with, and they will have permission to access it.

Use Inotify

Inotify (inode notify) is a Linux kernel subsystem that acts to extend filesystems to notice changes to the filesystem, and report those changes to applications. Syncthing does not support Inotify yet but there is an official extension module which talks to the Syncthing REST API. The usage of Inotify avoids expensive rescans every minute. The rescan interval of each folder is automatically increased to avoid expensive, regular rescans. Syncthing-inotify can be installed with the syncthing-inotify package. If Syncthing is managed through systemd, it is ensured by systemd dependencies that syncthing-inotify is started and stopped automatically.

Run a Relay

Since version 0.12 Syncthing has the ability to connect two devices via a relay when there exists no direct path between them. There is a default set of relays that is used out of the box. Relayed connections are encrypted in the usual manner, end to end, so the relay has no more insight into the connection than any other random eavesdropper on the internet [1]. To run a relay install syncthing-relaysrv-gitAUR from AUR and start it via systemd:

 # systemctl enable syncthing-relaysrv.service
 # systemctl start syncthing-relaysrv.service

More information about the syncthing-relaysrv-git package are available in the Syncthing forum.


See Debugging syncthing.