This month I managed to get my hands on an Opengear IP-PDU 9108 8 Port Switched & Metered PDU http://www.opengear.com/product-ip-pdu.html which seems to be a rebranded http://www.digipower.com.tw/PDU/BravoPDUswitched.htm. The PDU can be controlled over the network using a web interface or SNMP.
Digipower have an online demo available on the following link http://www.digipower.com.tw/PDU/BravoPDUswitched.htm, at the time of writing this post the address was http://211.75.143.21:8080 (snmp:1234). I’ll demo my code against this test system and if you want to test the code is a safe environment this could be useful for you.
Why bother if you have web and SNMP access?
Well I wanted to do this with native PowerShell cmdlets so that ruled out SNMP and to be quite honest the web portal is great for setting up the main configuration but a bit too long winded to turn a single socket on and off, or get a quick outlet status report. I also wanted to do this with web requests to that I could later use the same techniques learned for this post with an Arduino project I have on my to-do list.
Investigating the cgi and scripts running on the PDU
The PDU’s default configuration is to have the hostname set to “digiboard” so assuming DHCP is running on your network after a few seconds you’ll be able to connect to the web portal with http://digiboard. I navigated to the Control > Outlet (http://digiboard/outlet.htm) page and selected View Source, near the bottom of the code I noticed a mention of the status.xml:
newAJAXCommand('status.xml'
Let’s starts with the Status.XML, in my browser I loaded up http://digiboard/status.xml and the response was:
<?xml version="1.0"?>
<a href="http://digiboard/status.xml"><response></a><pot0>,,0.4,0.0,0.0,0.0,0.0,0.0,0.0,0.0,1,1,0,0,0,1,1,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,5,5,5,5,5,5,5,0.4,0,</pot0><outn>,,,,,,,,</outn></response>
Jackpot, now I needed to find where in that long response the actual statuses of each of the outlets were. I thought the best to make them stand out was to set them alternate e.g.
1,0,1,0,1,0,1,0 first
Result : ,,0.2,0.0,0.0,0.0,0.0,0.0,0.0,0.0,1,0,1,0,1,0,1,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,5,5,5,5,5,5,5,0.2,0,
and then 0,1,0,1,0,1,0,1.
Result: ,,0.2,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0,1,0,1,0,1,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,5,5,5,5,5,5,5,0.2,0,
This pattern was easy to spot and just to make things as clear as possible for this post I’ve bolded and underlined the areas of interest.
To read this with PowerShell I used the Invoke-WebRequest cmdlet but first I created a variable to hold the credentials to access the web portal (this is just to prevent entering the credentials on each request):
$cred = Get-Credential #Defaults are snmp:1234
$statusXML = Invoke-WebRequest -Uri http://digiboard/status.xml -Credential $cred
Collect the Sub String that we’re interested in:
$statusXML.Content.Substring(52,15)
0,1,0,1,0,1,0,1
That wraps up the Status.xml, now onto turning the outlets on and off.
Also on the http://digiboard/outlet.htm source code I noticed two functions of interest:
function GetGroupOn()
{
var s = '';
var i = 1;
//for(var i = 1; i < 3; i++)
for(var j = 1; j < 9; j++)
{
if( document.getElementById('C'+ i + j).checked )
s += 1;
else
s += 0;
}
s += "00000000" + "00000000";
if(confirm("turn on the outlet"))
newAJAXCommand('ons.cgi?led='+s, null, false);
}
function GetGroupOff()
{
var s = '';
var i = 1;
//for(var i = 1; i < 3; i++)
for(var j = 1; j < 9; j++)
{
if( document.getElementById('C'+ i + j).checked )
s += 1;
else
s += 0;
}
s += "00000000" + "00000000";
if(confirm("turn off the outlet"))
newAJAXCommand('offs.cgi?led='+s, null, false);
}
You can see from these two functions that either ons.cgi? or off.cgi? is called with two blocks of eight numbers, with a bit of luck I tried:
Invoke-WebRequest http://digiboard/offs.cgi?led=000000010000000000000000 -Credential $cred
Sure enough outlet 8 (H) turned off, let’s try and turn this back on:
Invoke-WebRequest http://digiboard/ons.cgi?led=000000010000000000000000 -Credential $cred
Yep, that worked!
I would guess that the second block of 8 numbers is for 16 outlet PDU’s but I cannot be sure.
Creating the Get-IPPDU function
Using what I discovered I wrote the following function to collect and format the current status of the outlets:
function Get-IPPDU {
<#
.NOTES
Author: John Milner aka jfrmilner
Blog : https://jfrmilner.wordpress.com
Post : http://wp.me/pFqJZ-5l
Requires: Powershell V3
Legal: This script is provided "AS IS" with no warranties or guarantees, and confers no rights. You may use, modify, reproduce, and distribute this script file in any way provided that you agree to give the original author credit.
Version: v1.0 - 06 Jan 2013
#>
param(
[System.Management.Automation.PSCredential]$Credential,
$URI = "http://digiboard"
)
try {
$statusXML = Invoke-WebRequest -Uri ($URI + "/status.xml") -Credential $Credential
}
catch {
$_.Exception.Message
break
}
$statusXMLArray = $statusXML.Content.Substring(52,15)
#Status Report
$outlet = 65
$statusReport = @()
foreach ($status in ($statusXMLArray -split ",") ) {
$statusReport += @{$("Outlet" + [char]$outlet)=$status}
$outlet++
}
$statusReport
}
This provides a couple of parameters, URI and Credentials, both are self-explanatory. Here is a screenshot of me trying this against the one on my LAN and the one from the demo site mentioned earlier.
Creating the Set-IPPDU function
Using what I discovered I wrote the following function to change the power states of outlets:
function Set-IPPDU {
<#
.NOTES
Author: John Milner aka jfrmilner
Blog : https://jfrmilner.wordpress.com
Post : http://wp.me/pFqJZ-5l
Requires: Powershell V3
Legal: This script is provided "AS IS" with no warranties or guarantees, and confers no rights. You may use, modify, reproduce, and distribute this script file in any way provided that you agree to give the original author credit.
Version: v1.0 - 06 Jan 2013
#>
param(
[Parameter(Mandatory=$true)]
[ValidatePattern("[A-H]{1,8}")]
[array]$Outlets,
[ValidateSet("On","Off")] $PowerState,
$URI = "http://digiboard",
[System.Management.Automation.PSCredential]$Credential
)
$outletKeys = [PSCustomObject][Ordered]@{A=0;B=1;C=2;D=3;E=4;F=5;G=6;H=7}
$statusKeys = [PSCustomObject][Ordered]@{ON=1;OFF=0}
$charArray = ("00000000").ToCharArray()
foreach ($request in $outlets ) {
$charArray[($outletKeys.($request))] = "1"
"Turn {0} {1}" -f $request, $powerState
}
$stateString = -join $charArray
$URI = ($URI + "/" + $powerState.ToLower() + "s.cgi?led=" + $stateString + "0000000000000000")
Invoke-WebRequest $URI -Credential $Credential | Out-Null
}
We have both the URI and Credentials parameters like the Get-IPPDU function, I also added “Outlets” which accepts the letter name of the Outlet or a comma separated collection of outlet letters and finally the PowerState which accepts On or Off. Here is a screenshot of me testing the functions against the IP PDU on my LAN.
I think this is another great example of the power of the new PowerShell 3 Invoke-WebRequest cmdlet and an interesting way to get PowerShell interacting with system/hardware it was never intended for.
These functions should work with any of the digipower PDU’s, such as the Amazing PDU and Bravo PDU. Thanks for reading and as always your comments are welcome.
Regards,
jfrmilner
jfrmilner's Tech Blog