Wake on LAN Usage

selimgoksu · October 21, 2016, 9:49am

Hi

When I use WoL by right-click on the console, how the signal arrives to end point ?
this is different from scheduled WoL ?

selimgoksu · October 21, 2016, 1:08pm

and
can I install relay and WoLF on the same host ?

AlanM · October 21, 2016, 5:37pm

When you use the console it messages a client within the same subnet to send the WOL packet to the MAC address of the endpoint you want to wake.

This would mean you have another client in the same subnet and have designated them a WOL forwarder, and that the other client can receive UDP messages from the relay architecture for it to work.

selimgoksu · October 21, 2016, 8:04pm

the message is sent to gateway IP of WoLF’s subnet.

from the relay to WoLF’s subnet, is the BES WOL message in type of broadcast or type of unicast?

how to debug right-click Wake on LAN ?

strawgate · October 23, 2016, 2:25pm

The message should be sent to the broadcast IP for the subnet.

One thing to make sure is that your clients are receiving UDP pings. When you right click and press, “Send Refresh” do your clients update quickly? Does their last report time change to right now when you send a refresh?

Each Wake-On-Lan Forwarder on the network will attempt to send a WOL packet to the target. You need to make sure that there is at least one Wake-On-Lan Forwarder on the subnet of the client.

In the past i’ve used Welcome To Depicus - Home of the Geek to troubleshooting Wake On Lan, essentially stop the besclient and set it to listen on UDP 52311. Once you send a WOL packet via the console you should see activity a couple of seconds later.

selimgoksu · October 23, 2016, 2:31pm

Thanks strawgate

I will try this tool also. it is hard to filter in wireshark.

these two udp pings are same ?
can “the udp message broadcasted by the relay” only be understood by the BigFix agent ? is this a bigfix specific message ?

strawgate · October 23, 2016, 2:36pm

The first thing you should do is make an analysis with a property called, “Last UDP Ping” with relevance of last command times of client

Or you can download and import this analysis from BigFix.Me

Once you have that analysis added, right click on a bunch of clients and press, “Send Refresh”. Within about a minute you should see dates/times populating the, “Last UDP Ping” property. If it stays are <error> then your environment does not have UDP pings working.

Without UDP Pings working, you cannot use Wake On Lan.

can “the udp message broadcasted by the relay” only be understood by the BigFix agent ? is this a bigfix specific message ?

The wake-on-lan message is not a BigFix specific message, it just happens to use UDP 52311 for the port. Remember, Wake-on-Lan occurs when the machine is off so there is necessarily no agent to receive the WOL. The Network Adapter itself handles receiving and waking up the machine.

selimgoksu · October 23, 2016, 9:12pm

Thanks very much strawgate.

I have a few more question to comprehend WoL:

how WoLF knows the target IP ?
(if it is latest registration ip of client), what if that ip is allocated by another machine ?

strawgate · October 23, 2016, 9:18pm

There is an analysis called, “Wake-On-LAN Analysis” in the BES Support site that has a property called, “BigFix Wake-on-LAN Subnet”

It’s based on this subnet that it determines which Wake-On-Lan Forwarders to use.

How Wake-On-Lan works is better learned through external resources like here: https://en.wikipedia.org/wiki/Wake-on-LAN The only unique part about BigFix is how it determines who sends out the Wake-On-LAN broadcast (the WoLF) once that happens you’re in standard WoL territory.

Wake-On-Lan is a layer 2 functionality (non-IP) and so all the matters is that the NIC is plugged into the right network. A sleeping/off machine does not have an IP address afterall. Once it finds the right Wake-On-Lan Forwarders to use the Forwarder sends a broadcast Wake-On-Lan packet on the network.

If the machine is no longer on that network it will necessarily not receive a Wake-On-Lan Packet.

selimgoksu · October 23, 2016, 9:23pm

if I want to wake up only one PC on my subnet, how WoL forwarder addresses it ?
by MAC Address ?

strawgate · October 23, 2016, 9:28pm

Hi,

I’d really recommend reading up on how Wake-On-Lan works to better understand how broadcasting a Wake-On-Lan packet achieves the effect you’re looking for.

Essentially it boils down to the fact that a Wake-On-Lan packet is a specially crafted packet (using the machine’s Mac Address) that will only wake up the targeted computer. Computers receiving a Wake-On-Lan packet destined for another machine will simply ignore the packet.

Hope that helps!
Bill