Provided by: syncthing_1.1.4~ds1-4_amd64 bug


       syncthing-networking - Firewall Setup


       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.

       In the absence of port forwarding, relaying may work well enough to get devices  connected
       and synced, but will perform poorly in comparison to a direct connection.


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

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

       · Port 21027/UDP (for discovery broadcasts on IPv4 and multicasts on IPv6)

   Uncomplicated Firewall (ufw)
       If   you’re   using   ufw   on   Linux   and   have   installed   the   Syncthing  package
       <>, you can allow the necessary ports by running:

          sudo ufw allow syncthing

       If you also want to allow external access to the Syncthing web GUI, run:

          sudo ufw allow syncthing-gui

       Allowing external access is not  necessary for a typical installation.

       You can then verify that the ports mentioned above are allowed:

          sudo ufw status verbose

       In case you installed Syncthing manually you can follow the instructions to  manually  add
       the syncthing preset <>
       to ufw.


       To be able to access the web GUI from other computers, you need to change the  GUI  Listen
       Address setting from the default to 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


       Syncthing can use a SOCKS5 proxy for outbound connections. Please see proxying.


       The Syncthing Authors


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