How do I tell Syncthing which networks are local, and which are global?

[lockywolf]

My problem is the following:

I want Syncthing to synchronise if and only if there are non-metered fast networks available.

In my setup that are two networks, 192.168.47.8/24 and 192.168.2.1/23.

For the rest of the networks, I need Syncthing to never try to send any data, as my traffic cost is 1$/mb.

I cannot bind to fixed addresses, because the IPs assigned dynamically via DHCP.

I have seen the “Always Local Nets” parameter, which I assigned to the aforementioned networks, but I have found no “Always Non-Local Nets”, which, I guess, I need to assign 192.168.1.1, which is a metered connection that I often have to connect to.

Is there any way to set restricted networks for Syncthing?

[calmh (Jakob Borg)]

Syncthing only considers the local LAN local, plus whatever you add as “always local nets”. But local or not just affects rate limiting, are you looking for the “allowed networks” per device instead?

[lockywolf]

What is a “local LAN”? I my case, 192.168.1.1/24 is not a local LAN.

How is that different from rate limiting? I thought that restricted networks are the ones where rate is limited to 0.

[calmh (Jakob Borg)]

Zero is not a valid rate, there needs to be an actual non-zero rate. “Local” for a network means the one the computer is actually directly connected to.

https://docs.syncthing.net/advanced/device-allowednetworks.html#allowed-networks

[lockywolf]

I still do not understand. There is a big difference between a local network that is a real “internal IP” network, and one that is a VPN, and as such, may actually have its endpoint at a remote machine.

[imsodin (Simon)]

Sure, there is a difference. What exactly a network means for Syncthing depends on user setup. Thus Syncthing gives you options - which Jakob pointed out to you:

1. Syncthing’s rate limiting does not apply to what Syncthing considers LAN:

@calmh

Syncthing only considers the local LAN local, plus whatever you add as “always local nets”.

@calmh

“Local” for a network means the one the computer is actually directly connected to.

2. Allowed networks per Device:

@calmh

are you looking for the “allowed networks” per device instead?

@calmh

allowedNetworks — Syncthing documentation

As he wrote, it sounds like what you are looking for is 2.

[odin (Herbert Snorrason)]

@lockywolf

I still do not understand. There is a big difference between a local network that is a real “internal IP” network, and one that is a VPN, and as such, may actually have its endpoint at a remote machine.

But … it’s literally the purpose of a VPN to hide that difference. The technologies used are deliberately built in order to make the remote network appear local to the user and operating system.