NAME

       syncthing-networking - Firewall Setup

ROUTER 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  forwarding  for  ports
       22000/TCP  and  22000/UDP  (or  whichever  port is set in the Sync Protocol Listen Address
       setting).  The external forwarded ports and the internal destination ports have to be  the
       same (e.g. 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.

   Local Discovery
       The router needs to allow/forward broad-/multicasts for local discovery to work.   Usually
       these  are  allowed  by  default  in  a  single  local  subnet, but may be blocked between
       different subnets or even between a bridged Wi-Fi and LAN.

       If you are unable to set up your router thus or your firewall as  shown  below,  and  your
       devices  have  static  IP addresses, you can specify them directly by changing the default
       dynamic setting for Addresses to something like: tcp://192.168.1.xxx:22000, dynamic.

LOCAL FIREWALL

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

       • Port 22000/TCP: TCP based sync protocol traffic

       • Port 22000/UDP: QUIC based sync protocol traffic

       • Port 21027/UDP: for discovery broadcasts on IPv4 and multicasts on IPv6

       If  you  configured a custom port in the Sync Protocol Listen Address setting, you have to
       adapt the firewall rules accordingly.

   Uncomplicated Firewall (ufw)
       If  you’re   using   ufw   on   Linux   and   have   installed   the   Syncthing   package
       <https://apt.syncthing.net/>, 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  <https://github.com/syncthing/syncthing/tree/main/etc/firewall-ufw>
       to ufw.

   Firewalld
       If  you  are  using  Firewalld  <https://www.firewalld.org/>  it  has included support for
       syncthing (since version 0.5.0, January 2018), and you can enable it with:

          sudo firewall-cmd --zone=public --add-service=syncthing --permanent
          sudo firewall-cmd --reload

       Similarly there is also a syncthing-gui service.

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.

VIA A PROXY

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

AUTHOR

       The Syncthing Authors

COPYRIGHT

       2014-2019, The Syncthing Authors