Magic packet for Wake on Wireless LAN?

networking network-programming network-protocols wake-on-lan
adib picture adib · Apr 15, 2017 · Viewed 11.9k times · Source

How to construct & send the magic packet for Wake on Wireless LAN?

The Wikipedia article on the subject only describes the standard Wake-on-LAN magic packet. However the same article describes that a supplementary standard would need to be used for waking up wireless hosts.

... If the computer being woken up is communicating via Wi-Fi, a supplementary standard called Wake on Wireless LAN (WoWLAN) must be employed....

Unfortunately I can't seem to find an authoritative source / method on how to implement Wake-on-LAN that for waking up nodes on WiFi.

Answer

Tony picture Tony · Apr 16, 2017

The blog that wikipedia linked to say:

The simple fact is that there is not enough industry support for WoWLAN to make it feasible for most organizations.

From TCP/IP Illustrated volume 1:

using PSM (power save mode) can affect throughput performance significantly as idle periods are added between frame transmissions and time is spent switching modes

So I am not sure you really want this feature.

I am not sure if there is a RFC standard about WoWLAN, but there exists PSM in 802.11, which make station into a limited power state and can be woke up by AP. In order to wake the station that in PSM, you just need to send your data message to it, and AP will notify that station in next Beacon frame.

Update:

Some notice:

  1. Only newer Macs support Wake-On-Lan over Wifi. If your Mac is a 2012 or older model, it probably does not support this feature.
  2. You cannot wake from off or hibernate mode the way you can on a PC. You can only wake it from sleep mode. Also note that after a certain amount of time sleeping they will hibernate automatically. You can check this with the pmset -g command. I believe it's the StandbyDelay setting.

Some steps:

  • Configure your Mac to allow wake from Wi-Fi in the power adapter section of Energy Saver
  • Use Remote Desktop or an equivalent tool to send the Wake-on-lan (WOL) packet to your router that will then deliver it to your sleeping Mac.
  • Use some tools like wireshark to view the magic packet structure and protocol, then you can try it through WiFi.

Ref:

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