PowerShell cmdlet: Send Magic Packet

PowerShell cmdlet (module/function) to send a magic packet based on provided MAC address(es). Comment-based help is included in the source-code: Get-Help Send-MagicPacket -Full

Contents

• Installation and verification
  • Example: Auto-load for current user
• Overview
• Broadcast considerations
• Pipeline
• Module or Function
• Feedback

Installation and verification

Downloads are available via my git server and GitHub. You may verify the cmdlet's integrity using CodeNotary via vcn authenticate or by dropping the downloaded script and/or manifest onto their verification webpage at https://verify.codenotary.io. Please always try to verify downloaded scripts and software regardless of the source!

If you are integrating this function with your own project or want to manually load the module as needed, then save the module and manifest file wherever it is convenient for you. If you want to auto-load this function so it is available automatically in any PowerShell session then you must extract it to a directory named wol-magicPacket somewhere defined in your PSModulePath depending on your use-case. More information can be found directly from Microsoft here .

Example: Auto-load for current user

Here's a complete example assuming I want the module automatically available for all sessions running under my user account:

# download version 1.1
Invoke-WebRequest -Uri https://git.asifbacchus.dev/asif/ps-cmdlet-wol/archive/v1.1.zip -OutFile "$Env:DOWNLOADS\ps-cmdlet-wol.zip"

# Get PSModulePath
# You should see a user-level modules path in the form of either:
#  C:\Users\Username\Documents\WindowsPowerShell\Modules  -OR-
#  C:\Users\Username\Documents\PowerShell\Modules
$Env:PSModulePath

# change directory to the appropriate path from above
Set-Location "C:\Users\Username\Documents\WindowsPowerShell\Modules"

# extract files and rename directory
Expand-Archive -Path "$Env:DOWNLOADS\ps-cmdlet-wol.zip" -DestinationPath .\
Rename-Item -Path ps-cmdlet-wol -NewName wol-magicPacket

# confirm: you should see a directory named 'wol-magicPacket'
gci

# confirm: you should see the manifest and module within the wol-magicPacket folder
gci .\wol-magicPacket

Now, close and re-open PowerShell and the Send-MagicPacket function should be available:

Get-Command Send-MagicPacket

Overview

The function sends two (2) magic packets spaced one (1) second apart. One set of magic packets will be sent per MAC address submitted either directly via the MacAddress parameter or via the pipeline (implicitly or explicitly). Usage examples are provided via Get-Help Send-MagicPacket -Examples.

The only mandatory parameter is MacAddress which can be provided directly or via the pipeline either implicitly or explicitly (parameter is in the first position). MacAddress is an array of strings. The actual hex values of the MAC address can be separated with a colon (':') and/or a hyphen ('-'). For example, the following MAC addresses are all valid even within the same command:

Send-MagicPacket '1a:2b:3c:4d:5e:aa', 'a1-b2-c3-d4-e5-bb', '1a:2b-3c:4d-5e-cc'

By default, the magic packet will be sent on the global broadcast address for your current system (e.g. 255.255.255.255) using UDP on the echo port (7). These options can be customized via parameters:

• -BroadcastIP | IP | Address: Broadcast address to use. By default, this is 255.255.255.255 but you really should use a subnet specific broadcast address instead (e.g. 192.168.1.255). See the Broadcast considerations section for more discussion.
• Port: Allows changing the UDP port over which the magic packet is sent. This is by default port 7 (echo). Port 9 ( discard) is also quite common but any port can be used depending on your particular environment.

The magic packet is constructed as per standards: 6 byte header consisting of '255' (hex:FF) followed by the hex-represented MAC addresses repeated 16 times.

Broadcast considerations

Long ago in a galaxy far away... actually a few decades ago right here on Earth, the easiest way to send Wake-On-Lan ( WOL) packets was simply to use the global IP4 all-subnets broadcast address of 255.255.255.255. Because this generates a lot of un-needed traffic, breaks subnet isolation and can be an attack vector, many routers and switches now block this type of broadcast. Although this remains the default for most WOL applications (including this function), it is vastly more reliable and preferred to use a subnet-specific broadcast address. For example, if you are concerned with computers on your subnet of 192.168.1.0/24 then you would use the broadcast address of 192.168.1.255.

More recently, it has also become somewhat common to use the multicast all-hosts address of 224.0.0.1 when sending WOL packets. If broadcast is not working in your environment, you may want to try this as a possible workaround.

Things become a little more complicated with IP6. There is no concept of 'broadcast' in IP6 and thus, you need to use multicast. I have not extensively tested IP6 WOL since I tend to continue using IP4 for this purpose (all my networks are dual-stack). I would assume the simplest place to start testing would be using the link-local all-nodes address of ff02::1. I suspect this should work across most networks, but I have not tested it extensively and it would depend greatly on switches, routers and even machine specific set-ups.

Pipeline

This function is geared toward pipeline usage. The variable MacAddress is parameterized and used by the function for an array of string objects representing individual MAC addresses. This is consistent with WMIC/CIMv2 output for most NIC queries and allows this function to be easily called using piped output from such a query. To see this, try sending some dummy magic packets to the localhost for all interfaces on the local machine:

# get name, manufacturer and MAC address for connected interfaces and pipe to our function 
Get-CimInstance -Query "Select * From Win32_NetworkAdapter Where NetConnectionStatus=2" | Select-Object Name, Manufacturer, MacAddress | Send-MagicPacket -IP 127.0.0.1 -Verbose

You will notice I've selected stuff we don't need (Name, Manufacturer) to show that the function can parse and pick up named the MacAddress of each object (network interface) and then send a magic packet to 127.0.0.1 on port 7 (echo). This is not at all useful, but demonstrates pipeline usage quite nicely, I think. A simpler demonstration would be the following:

# send magic packets to two machines over IP4 localhost using port 9 (discard)
'1a:2b:3c:4d:5e:aa', 'a1:b2:c3:d4:e5:bb' | Send-MagicPacket -BroadcastIP 127.0.0.1 -Port 9

Module or Function

This was intended to be used as a simple function that can be integrated into other scripts directly or, more conveniently, loaded as a module and referenced as needed in a variety of use-cases.

If using as a function, simply place it within your script. If you want to load it as a module either Load-Module within your script or do so at a PS prompt:

# load module
Load-Module C:\path\to\module\wol-magicPacket.psm1

# call module anytime after loading within the same session
Send-MagicPacket ...

Feedback

I coded this pretty quickly for a project I was working on in a small LAN deployment. I also use it routinely in networks of various sizes and over VPN connections and also when I'm too lazy to move from my office to the living room to turn on my media centre. I've polished it up and added comment-based help for the version in this repo, hence the more recent creation date. I'm always interested in improvements since I don't code in PowerShell that often and I'm sure this can be vastly improved. Please send any suggestions, bugs, etc. to me by filing an issue.

I hope you find this useful! As indicated by the license, you can use this code for whatever you want in any capacity. If you do use it, a link to my blog at https://mytechiethoughts.com would be greatly appreciated!