Making a Linux home server sleep on idle and wake on demand (2023)

Ha ha, I tried something similar when I had to go to Thailand for my wife's treatment. And failed spectacularly. Fortunately, my laptop had all the files. I didn't have Tailscale at that time.

My Desktop, WoL on, tested to be working Android Phone, always on

All have SyncThing installed. Mobile had Tasker installed.

So, the idea was to have Tasker monitor a folder inside SyncThing, When I need my computer, I put a file inside that folder, when Tasker finds that folder, it sends WoL to my desktop, and deletes the file, Computer wakes up. When I see the file deleted I know, the beast is now awakens ....

When I actually did try that from Thailand, the file did not got deleted, nor the beast woke up.

What happened? Turns out, my mobile restarts automatically after some time of inactivity. Which, locks Tasker out, and the whole process fails.

So, operation wake the beast was busted.

Why don't you send WOL directly over the internet? (You'll need to set up a permanent ARP record on the router.)

Or login into the router and send WoL from there?

Or have Raspberry always on with ssh?

Or set a power-on timer in BIOS/UEFI once a day and a shutdown/sleep in cron? (This is also a good failsafe if WoL doesn't work.)

> Why don't you send WOL directly over the internet? (You'll need to set up a permanent ARP record on the router.)

Hm, so never tried something like that before actually, I think for OpenWrt I need to install arp packages. I do not have public IP any more though, was getting hammered by bot network and found Tailscale to do what I need.

> Or login into the router and send WoL from there?

Restricted outside access to the router management panel, only port forwarded to the desktop.

> Or have Raspberry always on with ssh? I do not have one, which is why used a mobile, thought to be next best thing. As, power outages happen regularly, I need something that would be able to keep on running.

> Or set a power-on timer in BIOS/UEFI once a day and a shutdown/sleep in cron? (This is also a good failsafe if WoL doesn't work.)

That's easily workable for my setup, actually!

Thank you for giving me the ideas!

>> Why don't you send WOL directly over the internet? (You'll need to set up a permanent ARP record on the router.)

> Hm, so never tried something like that before actually, I think for OpenWrt I need to install arp packages.

No, you don't. Put this in /etc/firewall.user or /etc/rc.local (you can do it from UI) and forward a UDP port to 192.168.0.254 or whaterver subnet you're using:

  ip neigh add 192.168.0.254 lladdr ff:ff:ff:ff:ff:ff nud permanent dev br-lan extern_learn

The incoming packet will be broadcasted (ff:ff...) on the br-lan interface. 192.168.0.254 doesn't need to exist - the sleeping computer doesn't care.