Syncthing is an awesome project for synchronising data between devices. It can be seen as a real time backup, but probably a better comparison would be with a RAID 0 where same data is duplicated on a second drive. With Syncthing data is encrypted in transit, and it can be synchronised in multiple servers at the same time, or even store the data encrypted by a password if some provider is not trusted.
To work, Syncthing relies on public servers, because each server is identified by an ID, and that's about it. A comparison would be to how AnyDesk or Teamviewer work with IDs, only Syncthing is just for backups. The public servers are called relay servers, and the project needs as many as possible to run. A list of public relay servers contributing in real time can be found here.
To donate a server with Debian is easy. First Install Syncthing. I use Debian 13 Trixie and the Syncthing Relay software from its repository. In my case I simply ran apt install syncthing-relaysrv to install. Afterwards I edit the configuration in/etc/default/syncthing-relaysrv- my configuration is as follows:
NAT=false
STRELAYSRV_OPTS='-provided-by=DeFault -global-rate=410000'
NAT=false option specifies that I don't run it behind a NAT. Since I donate a server's bandwidth to this project, I don't have a NAT, therefore I set it to false.- The variable
STRELAYSRV_OPTS is defined in systemctl service file by default, so I used it to introduce other parameters. The valid settings can be found in the official documentation.
- I used the name of the owner donating the bandwidth as "DeFault", by using
provided-by parameter. This is a way for me to identify my servers in the public relays page of Syncthing.
- With regards to bandwidth and how many bytes per second can be donated, this is defined using
-global-rate parameter. Keep in mind this parameter refers to maximum bytes per second that may be used.
I hope this guide helps. Some providers may not accept donating bandwidth to some anonymity project (such as Tor), but a public backup project (or data synchronisation project) should not break their terms, which is why I decided to post this it case something like helps with those idling offers.
