WOL for different VLANs

[Mdearmas]

Hello,

I’m using FOG and have it set up on a certain VLAN. When PC is on DHCP under that VLAN, WOL works perfectly.

But when PC is set up with a static IP under a different VLAN (/24), WOL doesn’t work.

Settings I’ve made:

WOL Broadcast Management plugin, I wrote every VLAN used.

Subnet groups created.

BIOS Settings: Deep Sleep disabled, Wake on LAN/WLAN enabled, Block Sleep checked

Device Manager Ethernet Properties (all ON): Allow the PC to turn off this device to save power, allow this device to wake the PC, Only allow a magic packet to wake the PC.

Is there anything else I need to set up on FOG or outside FOG?

Thank you in advance for your help!

[george1421]

@Mdearmas This is only at the fringe of my knowledge, but WOL is a L2 protocol that won’t traverse routers until you have a helper service (like dhcp relay is for dhcp) that will forward directed broadcasts across your router. I understand why it works but not sure how to get your router to forward directed broadcasts to the intended target vlan.

[george1421]

@george1421 I was pretty close with my limited knowledge of this.

google-fu: router forward wol broadcast to different subnet

AI response
To forward Wake-on-LAN (WOL) broadcast packets across different subnets, you’ll generally need to configure your router to forward these packets, as they don’t inherently route like standard IP packets. This often involves enabling directed broadcasts or using a WOL proxy agent.
Here’s a breakdown of the process and some common methods:

1. Understanding the Challenge:

   WOL relies on a “magic packet” sent at the Ethernet layer, not the IP layer.
   Routers primarily handle IP traffic and don’t typically forward broadcast packets across subnets by default.

2. Methods for Forwarding WOL Packets:

   Subnet Directed Broadcasts:
   Configure the router to forward broadcast packets to a specific subnet.

This involves using the broadcast address of the target subnet (e.g., 192.168.1.255 for 192.168.1.0/24).
The router at the destination subnet needs to be configured to recognize and forward the WOL packet as a true broadcast.
This method allows you to target multiple subnets.

WOL Proxy Agent:

A WOL proxy agent acts as an intermediary, receiving WOL requests on one subnet and rebroadcasting them as a directed broadcast on the target subnet. 

This is often used for WOL over the internet or when directed broadcasts are not desired.

Using a Router with WOL Support:

Some routers, like those from CommScope, have native support for forwarding WOL packets. 

You may need to configure specific settings, like forwarding UDP port 9 (or 7) and using helper addresses.

3. Example Configuration (using Subnet Directed Broadcasts):

   Identify the Target Subnet: Determine the IP address range of the subnet you want to wake up.

Find the Broadcast Address: Calculate the broadcast address for that subnet (e.g., for 192.168.1.0/24, it’s 192.168.1.255).
Configure the Router:

Enable directed broadcasts (often under "ip forward-protocol udp"). 

Configure a helper address on the router’s interface facing the WOL server, pointing to the target subnet’s broadcast address.
Ensure UDP port 9 (or 7) is included in the forwarding rules.

Send the WOL Packet: Send the magic packet to the target subnet’s broadcast address.

[Mdearmas]

@george1421 Thanks for your help! I also don’t have a strong networking background, so everything is new. We have Cisco and Juniper switches (Layer 2), so I’m trying to figure out how to set them up since it’s not layer 3. I also read about setting up the firewall? But I’m not even sure what I’m talking about.

[george1421]

@Mdearmas I think I would start with your router. Look up the model and how to enable directed broadcasts, also look to see if there is any helper services that can be turned on to forward WOL packets to the target LAN. Your issue isn’t with FOG, but rather its a network infrastructure issue.

[Pikmin]

I have done this before on a Cisco switch but it’s been a while. Thought I share my notes on what commands are needed

# Vlan131 (fog server vlan)
ip helper-address 192.168.158.255

# Vlan158 (fog client on a different vlan)
ip directed-broadcast 101

# ip access-list extended 101
access-list 101 permit udp host 192.168.131.149 any eq 9
* NOTE in the ACL above 192.168.131.149 is the fog server ip address

# forward udp
ip forward protocol udp 9 (it might say discard)



# On the switch the two vlans look something like this

interface Vlan131
 description fog server vlan
 ip address 192.168.131.1 255.255.255.0
 ip helper-address 192.168.131.3 (my dhcp & dns server)
 ip helper-address 192.168.158.255 (fog client subnet broadcast address)
end

interface Vlan158
 description fog client vlan
 ip address 192.168.158.1 255.255.255.0
 ip directed-broadcast 101 (extended ACL)
end

Hope it helps