SYNCTHING-NETWORKING(7)

NAME
syncthing-networking - Firewall Setup

PORT FORWARDS

If you have a NAT router which supports UPnP, the easiest way to get a working port forward is to make sure UPnP setting is enabled on both Syncthing and the router – Syncthing will try to handle the rest. If it succeeds you will see a message in the console saying:

Created UPnP port mapping for external port XXXXX on UPnP device YYYYY.

If this is not possible or desirable you should set up a port forward for port 22000/TCP, or the port set in the Sync Protocol Listen Address setting. The external forwarded port and the internal destination port has to be the same (i.e. 22000/TCP).

Communication in Syncthing works both ways. Therefore if you set up port forwards for one device, other devices will be able to connect to it even when they are behind a NAT network or firewall.

LOCAL FIREWALL

If your PC has a local firewall, you will need to open the following ports for incoming traffic:

•   Port 22000/TCP (or the actual listening port if you have changed the Sync Protocol Listen Address setting.)

•   Port 21025/UDP (for discovery broadcasts)

REMOTE WEB GUI

To be able to access the web GUI from other computers, you need to change the GUI Listen Address setting from the default 127.0.0.1:8384 to 0.0.0.0:8384. You also need to open the port in your local firewall if you have one.

  Tunneling via SSH

If you have SSH access to the machine running Syncthing but would rather not open the web GUI port to the outside world, you can access it through a SSH tunnel instead. You can start a tunnel with a command like the following:

ssh -L 9999:localhost:8384 machine

This will bind to your local port 9999 and forward all connections from there to port 8384 on the target machine. This still works even if Syncthing is bound to listen on localhost only.

You can forward multiple ports corresponding to many machines this way, but because Syncthing uses session cookies for the entire domain (i.e. your local machine), you will need to connect to each control panel in a separate browser instance or explicitly issue a browser reload when switching between them.

AUTHOR
The Syncthing Authors

COPYRIGHT
2015, The Syncthing Authors