Are multiple sub-networks supported?

[oliver124810]

Hi,

I have an UpSnap running fine on a given network, and now I would like to wake up devices on an additional, separated network. I have added an interface and I am able to ping the devices on the first and second network from the host where UpSnap is running, however, UpSnap will not wake up devices in the second network. Before I investigate further, I wanted to ask here if this use case is supposed to work at all.

Thanks for your help!

[seriousm4x]

Making wake on lan work across different subnets can be quite challenging. You can get the best change to make it work by setting the device netmask to "255.255.255.255". Is that does not work, it's most likely not an issue with UpSnap but more with your network setup. In that case google can help you more than I can.

[MrTux007]

Hi

I just moving to UpSnap, it's great and works with this one issue of WoL in a different network. In my opinion the issue is, that the used WoL binary "ether-wake" doesn't support it. I'm using "wakeonlan" on my Linux-PC and you can put the destination IP address and the MAC address as parameters and this is working to wake up devices in a different LAN (even over a VPN connection). Would be great if you could integrate wakeonlan, if you need someone to test, let me know.

The tool I'm using (in Linux Mint): Homepage: https://github.com/jpoliv/wakeonlan

thanks for this great tool

[MrTux007]

just seen that wakeonlan is in the edge Branch, maybe awake would also work (is in Alpine v3.23 available), as there you can also put the destination ip address as a parameter

[MrTux007]

I did a small test. I installed the alpine docker and awake in the container. Then I used awake (with -d ) to wake up a device in a different lan, it works.
@seriousm4x: Would be great if you could replace ether-wake with awake or add awake and implement an option where we can choose which to use.

thanks

[MrTux007]

I think I'm wrong with the assumption that linux binaries are used, I saw in the code that there is a net library in use. I will open a feature request.

[oliver124810]

Thank you, I will try it out! Do you why it is so challenging? UpSnap has the IP address of the device, the interface where to send the WoL packet can be derived easily from it.

[seriousm4x]

Not quire sure what you mean. The IP address has nothing to do with wake on lan. The IP is only used for pinging the device if it's online.
Wake on lan works by sending a packet to the mac address via the broadcast ip. Those are the 2 relevant values here. Knowing the only IP does not help.

[oliver124810]

This clear to me. What I mean is that the only difference between single-lan and multi-lan is that the packet must be sent on the proper interface. Since UpSnap knows the expected IP address, it can easily determine the proper interface (assuming the device IP is in the corresponding subnet, which is generally the case).

[Fred-DTV]

I saw that upsnap just sends the package for the device on subnet 2, to the main subnet 1 instead.
So my temporary solution was to have a (yes vibe-coded) WOL relay forward it to the other one:

#!/usr/bin/env python3
import socket

# adjust these if your subnets change
BCAST_10 = ("10.10.10.255", 9)
BCAST_42 = ("10.42.255.255", 9)

def main():
    # socket for receiving WOL (UDP/9, broadcast included)
    sock_in = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock_in.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    sock_in.bind(("0.0.0.0", 9))  # listen on all interfaces, port 9

    # socket for sending rebroadcasts (different local port)
    sock_out = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock_out.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)

    print("WOL relay listening on UDP/9, relaying 10.10 -> 10.42", flush=True)

    while True:
        data, addr = sock_in.recvfrom(1024)
        src_ip, src_port = addr
        print(f"Got WOL packet from {src_ip}:{src_port}, len={len(data)}", flush=True)

        # Only relay packets that *originate* from 10.10.x
        if src_ip.startswith("10.10."):
            # forward only to 10.42 broadcast
            sock_out.sendto(data, BCAST_42)

if __name__ == "__main__":
    main()

and then i have this running as a service on my lxc where only upsnap is running