I have an Airport Time Capsule connected to my internet service provider and a Linux server wired to one of the LAN ports on my airport. I want to be able to use the Wake-on-LAN feature to wake my Linux box from sleep/suspend from anywhere -- not just from my local network.
First approach that partially works
I've gone into Airport Utility and set up a stable IP based on the MAC address of my Linux box's Ethernet controller. I then set up port forwarding for magic packets on public UDP port 29999 to private port 9 and the 10.0.1.x address I assigned to my linux box.
This works from both outside and inside my network, but only for about 15 minutes after the linux box sleeps. After that I guess the Airport loses track of it and doesn't know where to route the packet.
Second approach that seems like it would work
If I forward the magic packet to the broadcast IP for my network, 10.0.1.255, then the box does wake even after a long time has passed...at least that works from my local network where I can tell the wake program on my Mac or WOL app on my phone which address to send the packet to.
But I can't test it from outside my network because the Airport Utility won't let me forward to .255.
Fix for this
I found several posts (which I can't find again today) that say if you can't forward to the broadcast IP at 10.1.0.255 to set the subnet mask to 255.255.255.128 and then forward to 10.1.0.127, but Airport Utility doesn't have anywhere to set the subnet mask.
I found another post yesterday (which I can't find today) which suggested exporting the Airport Utility configuration file and editing the subnet mask in there and reuploading. I did that, but it didn't work.
I need to port forward a Wake-on-LAN magic packet from the Internet, through my Airport Time Capsule to the broadcast IP of my private local network.
The broadcast address is 10.0.1.255, but Wake-on-LAN won't let me enter 255.
How can I wake my Linux box from the Internet? Is there a way to send the packet to the broadcast IP? Is there some other solution that changing the subnet mask? Is there some other solution that I should be thinking about?