need help with enabling external wake on lan (WOL)

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grither88

Commendable
Jul 27, 2016
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Trying to get external WOL setup for my home PC. I’ve had it working in the past, but my Linksys router fried, and I’m now trying to get it working with my provider’s router (a cisco router)

First of all, WOL works perfectly fine from inside my network. As long as I’m on wifi for my local network, I can turn the PC with WOL every time. So quite confident that I have the PC and NIC setup correctly

I’m trying to get external working

I have a port forward on UDP 9 to my Pc’s address 192.168.0.77
I also have a DCHP reservation setup directing 192.168.077 to my PC’s mac address.

I set the above up through some reading I’ve done.

Here’s the weird thing: with the above setup, I can wake the computer up remotely (example, using my iphone in the house BUT with wifi shut off, so although I’m standing in front the computer, I’m sending the packet over the cell network, which I assume is external, not internal)
So while that works once, I can not do it again! Other reading I've done says this may have something to do with a required ARP entry, which I could do on my old (fried) router running DDWRT, however this new router doesn’t appear to have any place to enter scripts etc.

Any advice on how to get this working? I’m somewhat encouraged that this is working (once) but not sure how to get it repeatable?
 
Solution
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Your problem is what you want to do is wake on WAN which is does not really exist. All implementation are some form of hack.

The next problem is all the misinformation you find on this topic. There are no IP addresses or port numbers or any of that. A wake on lan packet is purely a packet set to the broadcast MAC address containing the MAC address to be woken stored in a unique pattern.

The largest issue with attempting these hacks is the assumption a machine has some form of IP address. IP address are only used at the OS level. Say you had 2 different boot disks with 2 different ip address hard coded. When the machine is not running how would anything know which IP was valid.

All that matters is the mac address.

As it...
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bill001g

Titan
Aug 9, 2012
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Your problem is what you want to do is wake on WAN which is does not really exist. All implementation are some form of hack.

The next problem is all the misinformation you find on this topic. There are no IP addresses or port numbers or any of that. A wake on lan packet is purely a packet set to the broadcast MAC address containing the MAC address to be woken stored in a unique pattern.

The largest issue with attempting these hacks is the assumption a machine has some form of IP address. IP address are only used at the OS level. Say you had 2 different boot disks with 2 different ip address hard coded. When the machine is not running how would anything know which IP was valid.

All that matters is the mac address.

As it appears you have found out there are massive issue with things like ARP when you attempt these hacks.

The only hack that works most the time is.

1. Choose a unused ip address.
2. Port forward the external IP to this ip....what port you use depends to a point on the app generating the data.
3. Put in a static ARP entry mapping this dummy address to the mac FF:FF:FF:FF:FF:FF.....ie the broadcast mac.

Likely as you have found you can not put in the ARP entry on most routers. Even many you can do not allow you to map to the broadcast mac address since it can be used for denial of service attacks. This is also why you can not map ports to the broadcast IP of the lan segment, that used to be a common method to solve this before routers disabled the ability.

The best way to do this is with a router like asus that has a helper type of feature. You in effect log into the router and ask it to send the packet. When this type of function was used in enterprise installation years ago you always put in a slave machine that was always on to wake the others. Now days ILO like functions has replaced any need for WoL.

I suspect the answer is you can't do what you want with the router you have.
 
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grither88

Commendable
Jul 27, 2016
2
0
1,510
thanks for the detailed reply. i suspected it was not going to work with the ISP router. I did not use the feature too much but on occasion it was extremely helpful when travelling etc
 
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