Domain Health Report.ps1

It's been a while since I posted, so I figured I'd show you a little something I whipped out a few days ago. The script is a sort of "domain health report," and it sends out a nicely-formatted email with its findings. I have the script set in a scheduled task to run nightly. Every morning when I wake up, the email is there waiting for me in my inbox. The script uses the Active Directory Powershell module to get a list of all the computer accounts and user accounts in your domain. After displaying some general domain stats, based on the enabled computer accounts that it finds, it then attempts to find information from all of those machines. The information will be highlighted in red and bold if it falls below a certain threshold, e.g. disk space below 10%, an SSI below 7, etc.

So without further ado:

# DomainReport.ps1
# Emails a report of various metrics collected from every computer in the domain.
# This script is intended to be run automatically, on a schedule of once a day or so,
# to let us know how our domain is doing.

[string]$senderName   = "Domain Health Report"
[string]$senderAddr   = "dc1@domain.myotherpcisacloud.com"
[string]$recptName    = "Ryan Ries"
[string]$recptAddr    = "ryanries09@gmail.com"
[string]$emailSubject = "Domain Health Report"
[string]$smtpServer   = "smtp.domain.myotherpcisacloud.com"
[string]$emailBody    = ""
[int]$staleCompAcctDays = 60
[int]$staleUserAcctDays = 60
[int]$diskFreePercentThreshold = 10
[int]$SSIIndexThreshold = 7

Import-Module ActiveDirectory	# It will not hurt if the module is already loaded.

$localhost = Get-Content env:Computername
$domain = Get-ADDomain
$forest = Get-ADForest
$allComputerAccts = Get-ADComputer -Filter * -Properties *
$enabledComputerAccts = Get-ADComputer -Filter 'Enabled -eq $true' -Properties *
$allUserAccts = Get-ADUser -Filter * -Properties *
$enabledUserAccts = Get-ADUser -Filter 'Enabled -eq $true' -Properties *

Function Ping-Server
{
    param($hostName)
    trap
    {
        $false; continue
    }
	$object = New-Object System.Net.NetworkInformation.Ping
	$object.Send($hostName, 2000) #2000ms ping timeout
}

$emailBody += "<FONT STYLE=`"font-size:30px;`">"
$emailBody += "Domain Health Report"            
$emailBody += "</FONT>"
$emailBody += "<FONT STYLE=`"font-size:9px;`">"
$emailBody += "<BR/>Report executed from $localhost at $(Get-Date)<HR/>"
$emailBody += "</FONT>"
$emailBody += "<FONT STYLE=`"font-family:Monospace;font-size:13px`"><BR/>"
$emailBody += "<strong>Forest Root Domain:</strong> $($forest.RootDomain) ($($forest.ForestMode))<BR/>"
$emailBody += "<strong>Current Domain:</strong> $($domain.Name), NetBIOS $($domain.NetBIOSName) ($($domain.DomainMode))<BR/>"
$emailBody += "<BR/>"
$emailBody += "<strong>Domain Controllers:</strong> $($domain.ReplicaDirectoryServers.Count) Writable, $($domain.ReadOnlyReplicaServers.Count) RODCs, $($forest.GlobalCatalogs.Count) Global Catalogs<BR/>"
$emailBody += "<strong>Schema Master:</strong> $($forest.SchemaMaster)<BR/>"
$emailBody += "<strong>Domain Naming Master:</strong> $($forest.DomainNamingMaster)<BR/>"
$emailBody += "<strong>Infrastructure Master:</strong> $($domain.InfrastructureMaster)<BR/>"
$emailBody += "<strong>RID Master:</strong> $($domain.RIDMaster)<BR/>"
$emailBody += "<strong>PDC Emulator:</strong> $($domain.PDCEmulator)<BR/>"
$emailBody += "<strong>Sites:</strong> $($forest.Sites)<BR/>"
$emailBody += "<BR/>"
$emailBody += "<strong>Computer Accounts:</strong> $($allComputerAccts.Count) found, $($enabledComputerAccts.Count) enabled<BR/>"
if($allComputerAccts.Count -gt $enabledComputerAccts.Count)
{
	$emailBody += "<strong>Disabled Computer Accounts:</strong> "
	ForEach($_ in $allComputerAccts)
	{
		if($_.Enabled -eq $false)
		{
			$emailBody += "$($_.CN)`, " 
		}
	}
	$emailBody = $emailBody -Replace "..$" # Trim off the last two characters
	$emailBody += "<BR/>"
}
$emailBody += "<strong>Stale Computer Accounts<sup>*</sup>: </strong> "
ForEach($_ in $allComputerAccts)
{
	if($_.PasswordLastSet -lt $((Get-Date).AddDays(-$($staleCompAcctDays))))
	{
		$emailBody += "$($_.CN)`, "
	}
}
$emailBody += "<BR/><BR/>"
$emailBody += "<strong>User Accounts: </strong> $($allUserAccts.Count) found, $($enabledUserAccts.Count) enabled<BR/>"
if($allUserAccts.Count -gt $enabledUserAccts.Count)
{
	$emailBody += "<strong>Diabled User Accounts:</strong> "
	ForEach($_ in $allUserAccts)
	{
		if($_.Enabled -eq $false)
		{
			$emailBody += "$($_.SAMAccountName)`, "
		}		
	}
	$emailBody = $emailBody -Replace "..$"
	$emailBody += "<BR/>"
}
$emailBody += "<strong>Stale User Accounts<sup>*</sup>: </strong> "
ForEach($_ in $enabledUserAccts)
{
	$lastLogon = [DateTime]::FromFileTime($_.LastLogonTimeStamp)
	if($lastLogon -lt $((Get-Date).AddDays(-$($staleUserAcctDays))))
	{
		$emailBody += "$($_.SAMAccountName)`, "
	}
}
$emailBody += "</FONT><BR/><BR/>"
$emailBody += "<FONT STYLE=`"font-size:9px;`">* A `"stale`" computer account is one that has not updated its machine password with AD in $staleCompAcctDays days."
$emailBody += "<BR/>* A `"stale`" user account is not disabled but has not logged on to the domain in $staleUserAcctDays days."
$emailBody += "</FONT>"
$emailBody += "<HR/><BR/>"

ForEach($_ in $enabledComputerAccts)
{
	$emailBody += "<FONT STYLE=`"font-size:16px;`">"
	$emailBody += "<strong>$($_.CN)</strong> <BR/>"
	$emailBody += "</FONT>"
	$emailBody += "<div style=`"border-width:1px;border-style:solid;margin:2px;padding:2px;`">"
	$emailBody += "<FONT STYLE=`"font-family:Monospace;font-size:13px`">"
	$pingNode = Ping-Server $($_.CN)
	$emailBody += "<strong>Ping:</strong> "
	if($pingNode.Status -ne "Success")
	{
		$emailBody += "<FONT STYLE=`"color:red;`"><strong>NO REPLY!</strong></FONT><BR/>"
	}
	else
	{
		$emailBody += "$($pingNode.RoundTripTime) ms reply from $($pingNode.Address)<BR/>"
	}
	$computerSystem = Get-WmiObject Win32_ComputerSystem -ComputerName $($_.CN)
	$emailBody += "<strong>System: </strong> $($computerSystem.Manufacturer) $($computerSystem.Model)<BR/>"
	$latestStabilityIndex = Get-WmiObject Win32_ReliabilityStabilityMetrics -ComputerName $($_.CN) | Select-Object -First 1 | ForEach {$_.SystemStabilityIndex}
	$emailBody += "<strong>Latest SSI<sup>*</sup>: </strong>"
	if($latestStabilityIndex -gt 0 -and $latestStabilityIndex -le 10)
	{
		if($latestStabilityIndex -lt $SSIIndexThreshold)
		{
			$emailBody += "<FONT STYLE=`"color:red;`"><strong>$latestStabilityIndex<BR/></strong></FONT>"
		}
		else
		{
			$emailBody += "$latestStabilityIndex<BR/>"
		}		
	}
	else
	{
		$emailBody += "<FONT STYLE=`"color:red;`"><strong>NO DATA!</strong></FONT><BR/>"
	}
	
	## Don't want to use $log.Count here because it seems to be implemented inconsistently in the Get-Eventlog cmdlet,
	## e.g. sometimes it is null when it should be zero, and vice versa, and still other times it throws an exception
	## for no matches found.

	$emailBody += "<strong>Application Log Errors Last 24hrs: </strong>"
	Try
	{
		$appLogErrors = Get-EventLog -Log Application -EntryType Error -After $(Get-Date).AddHours(-24) -ComputerName $($_.CN)
		if($appLogErrors -eq $null)
		{
			$emailBody += "0<BR/>"
		}
		else
		{
			## This technique doesn't work if $log is null. $counter goes to 1 when it should stay at 0.
			$counter = 0
			$appLogErrors | ForEach-Object { $counter++ }
			$emailBody += "$counter<BR/>"
		}
	}
	Catch 
	{ 
		$emailBody += "<FONT STYLE=`"color:red;`"><strong>$($_.Exception.Message.ToString())</strong></FONT><BR/>" 
	}
	
	$emailBody += "<strong>System Log Errors Last 24hrs: </strong>"
	Try
	{
		$sysLogErrors = Get-EventLog -Log System -EntryType Error -After $(Get-Date).AddHours(-24) -ComputerName $($_.CN)
		if($sysLogErrors -eq $null)
		{
			$emailBody += "0<BR/>"
		}
		else
		{
			$counter = 0
			$sysLogErrors | ForEach-Object { $counter++ }
			$emailBody += "$counter<BR/>"
		}

	}
	Catch
	{
		$emailBody += "<FONT STYLE=`"color:red;`"><strong>$($_.Exception.Message.ToString())</strong></FONT><BR/>"
	}
	
	$emailBody += "<strong>Security Audit Failures Last 24hrs: </strong>"
	Try
	{
		$secLogErrors = Get-EventLog -Log Security -EntryType FailureAudit -After $(Get-Date).AddHours(-24) -ComputerName $($_.CN)
		if($secLogErrors -eq $null)
		{
			$emailBody += "0<BR/>"
		}
		else
		{
			$counter = 0
			$secLogErrors | ForEach-Object { $counter++ }
			$emailBody += "$counter<BR/>"
		}

	}
	Catch
	{
		$emailBody += "<FONT STYLE=`"color:red;`"><strong>$($_.Exception.Message.ToString())</strong></FONT><BR/>"
	}

	$emailBody += "<strong>Total RAM: </strong>$([math]::Round($computerSystem.TotalPhysicalMemory/1GB,0)) GB <BR/>"
	$emailBody += "<strong>Logical Disks:</strong>"
	$emailBody += "<div style=`"border-width:1px;border-style:dashed;margin:8px;padding:8px;background-color:`#dddddd`">"
	$computer = $($_.CN)
	ForEach($_ in $(Get-WMIObject -Query "SELECT DeviceID FROM Win32_Logicaldisk WHERE DriveType=3" -Computer $computer | ForEach { $_.DeviceID }))
	{
		$logicalDisk = Get-WMIObject -Query "SELECT * FROM Win32_Logicaldisk WHERE DeviceID='$_'" -Computer $computer
		$freespace = [math]::Round($logicalDisk.FreeSpace/1GB,0)
		$totalSize = [math]::Round($logicalDisk.Size/1GB,0)
		if((($freespace/$totalSize)*100) -lt $diskFreePercentThreshold)
		{
			$emailBody += "<strong><FONT STYLE=`"color:red;`">$($logicalDisk.DeviceID) ($($logicalDisk.VolumeName)) $freespace GB free out of $totalSize GB </FONT></strong><BR/>"
		}
		else
		{
			$emailBody += "$($logicalDisk.DeviceID) ($($logicalDisk.VolumeName)) $freespace GB free out of $totalSize GB <BR/>"
		}	
	}
	$emailBody += "</DIV>"
	$emailBody += "</FONT></DIV><BR/><BR/>"
}

$emailBody += "</FONT>"
$emailBody += "<FONT STYLE=`"font-size:9px;`">* SSI = Windows System Stability Index. Configure WMI Reliability Providers across your domain via Group Policy and ensure that the RAC scheduled task is running on the machines in order to gather this data.<BR/>"
$emailBody += "* The Remote Registry service must be running on remote computers in order to gather event log data."
$emailBody += "</FONT>"

Send-MailMessage -From "$senderName <$senderAddr>" -To "$recptName <$recptAddr>" -Subject "$emailSubject" -Body $emailBody -SMTPServer $smtpServer -BodyAsHTML

Enabling Win32_Reliability WMI Classes for Windows Server

I really like the Win32_Reliability classes, Win32_ReliabilityRecords and Win32_ReliabilityStabiltyMetrics. I used one of them in a previous post. They basically hold records of all the useful system events that relate to system configuration and stability, such as unexpected shutdown events, application errors and software installs/uninstalls, etc. To boot, Windows uses all those events to calculate a System Stability Index. Some people might think the SSI is unnecessary, but I personally really like it as a quick at-a-glance number that I can use to give me an idea of overall system health when I have a thousand machines to look at. It's basically an index from 0 to 10 that fluctuates based on the aforementioned system stability events. Machines with an SSI below a certain number need to be looked at more closely, you get the idea.

The difference is in my previous post, I didn't realize that the Win32_Reliability classes are not enabled by default on Windows 2008 R2 servers. On Windows 7 they are enabled by default, and on the one Windows 2008 Server (non-R2) on which I used them, they were functioning, which means that they're either enabled on 2008 Server by default or someone had turned them on previously.

You can, of course, access both these WMI classes in Powershell with the good old Get-WMIObject that we all know and love, like this:

Get-WMIObject win32_reliabilityrecords
Get-WMIObject win32_reliabilitystabilitymetrics

On a Windows 2008 R2 server that does not have these two classes enabled, you will get the error

Get-WmiObject : Provider load failure

whether you are executing the Powershell cmdlet locally or remotely. So as I started to research this problem, it seemed to be a simple matter of enabling the GPO setting "Configure Reliability WMI Providers." (This article from The Scripting Guy is pretty much all you need for that.) So I did that and applied it to all of my servers. And then I waited. I waited for 24 hours. Still nothing. I got onto one of the servers and ran gpupdate /force. Then I waited some more. (Maybe it needs time to gather the data, right?) 24 hours later, nothing. Rebooted the server. Nothing.

OK, that GPO setting is obviously not the only piece of the puzzle here. I researched a little more and The Scripting Guy showed up yet again!

So there is a Scheduled Task named "RacTask" in Scheduled Tasks -> Task Scheduler Library -> Microsoft -> Windows -> RAC. (Make sure you are set to view hidden tasks, just in case.) That task has two triggers - one that only fires when a new Application log event 1007 from Customer Experience Improvement Program shows up, and another that runs indefinitely every hour. On Server 2008 R2, by default, the first trigger is enabled while the latter trigger is disabled. (On client OSes like Win7, both triggers are enabled by default.) So the GPO setting alone would have worked, except that I had not gotten an event ID 1007 from CEIP in three days. Event 1007 from CEIP is "Successfully sent CEIP data to Microsoft." I have only gotten Error 1008s (Failure to send data to Microsoft) in the past three days. I'm choosing that to mean there's something wrong with Microsoft's SQM servers at the moment. Maybe they're down for maintenance or just too busy...

Needless to say, you'd never get event 1007s at all if you opted out of the Customer Experience Improvement Program, in which case simply changing that GPO setting would definitely not be enough. I'm not saying that you have to participate in CEIP on your servers if you want to use the Win32_Reliability monitors. But you do need to enable that second trigger on the scheduled task. Enable the trigger, run the task, and then you'll be able to access the WMI classes immediately, locally and remotely.

$latestStabilityIndex = Get-WmiObject Win32_ReliabilityStabilityMetrics -ComputerName $server | Select-Object -First 1 | ForEach {$_.SystemStabilityIndex}

That's how you kick it off manually. I should note that I received a 1007 (data sent successfully) on one of my servers the next day, which enabled the monitors as expected. (The CEIP uploader is set to attempt to collect and upload data every 19 hours by default.)

So the moral of the story is enabling the GPO setting "Configure Reliability WMI Providers" in the Computer Config -> Administrative Templates area is enough to enable the use of the Win32_Reliability WMI classes on your Win2K8R2 servers if they are participating in CEIP and you are willing to wait until they are able to successfully upload CEIP data, which could take one to several days. Otherwise, you're going to have to find a way to also kick off that scheduled task on all your servers, be it manually or scriptomatically.

I don't feel like this was altogether implemented that well in that regard. I do like the reliability data, but I don't feel like it should be related to or dependent on CEIP events at all. Also, while trying to come up with hypothetical ways to automate the enabling of this so that I wouldn't have to log on to every server:


Come on Microsoft, get it together!

Monitoring with Windows Remote Management (WinRM) and Powershell Part II

For the first installment of this series, click here. This is yet another post that required hours of research and testing and resulted in me learning way more about various tangential things than I realized I wanted to know.

Ready to wrap this up with some real security goodness? Me too.

When you operate a small network or LAN, passing your credentials over the wire via easy-to-crack hashes and sending other traffic as clear text might be acceptable to you - or more accurately, you don't spend any time thinking about it. But when your network is large, heterogeneous and spans dozens of cities and continents, and has hundreds of internet-facing nodes and thousands of employees and external users... you need to start paying more attention to security. Well actually you needed to have started paying more attention to security way before you got to that point, but you get my meaning. You never know who might be listening with an intent to uncover privileged information - whether outside hackers or internal employees.

When I first set out writing this post, I didn't realize that all WinRM traffic is already encrypted by default. Even when sent over the HTTP protocol and even when Negotiate/NTLM authentication is used. It's still encrypted. But I don't mean to conflate authentication and data encryption right off the bat. Let's start with encryption. Here is an example of the header of an HTTP packet sent to a WinRM server:

POST /wsman?PSVersion=2.0 HTTP/1.1
Connection: Keep-Alive
Content-Type: multipart/encrypted;protocol="application/HTTP-SPNEGO-session-encrypted";boundary="Encrypted Boundary"
User-Agent: Microsoft WinRM Client
Content-Length: 1662
Host: server1:5985

SPNEGO is used to negotiate the strongest authentication type available to both nodes, and then everything in the payload of the packet between the "--Encrypted Boundary--" tags... is gibberish. There is no clear text in the packets. I've looked. The only bit of useful information I could find so far while sniffing on the wire was the domain\username used for authentication. I'm guessing that this encrypted data sent over HTTP must be new to WinRM 2.0, because this Technet article implies that data sent over HTTP was clear text at some point.

*Click for larger*

Since the nodes are using the Negotiate protocol, they will settle on the best authentication mechanism that they can both agree upon. (Kerberos > NTLMv2 > NTLMv1, etc.) In this case it's going to be NTLMv2 authentication since they can't use Kerberos since they aren't in the same AD domain. Windows machines haven't used the old easy-to-crack LAN Manager or NTLMv1 password hashes in over 10 years. If you search through your packet capture, (use the "ntlmssp" display filter in Wireshark to easily find the relevant authentication traffic,) you will find several hashes of varying lengths, including the server challenge, client response, client challenge, HMAC, session key, MIC, etc. What's important though is that nothing that directly exposes the actual password is sent over the wire. If the machine has already been compromised, the attacker could access the local SAM and get an unsalted password hash that, using something like Rainbow Tables, could eventually be decoded into the original password. But that's only if the Security Accounts Manager on the local machine has already been compromised. The hash that's stored there is not sent over the wire.

This guy right here has an ongoing, amazing 6-part (and growing) exposé on getting at those infamous NTLM hashes. It always involves already having access to the machine though, and almost always involves old versions of Windows and exploiting flaws that have since been fixed.

In the first part of this tutorial, we did a basic set up of the WinRM service on a standalone computer named SERVER1. Then we connected to that computer from a domain-joined machine named DC01 to demonstrate using the Negotiate authentication protocol to connect to machines that are outside of your Active Directory trust boundary. By the way:

It should be noted that even within a domain, for Kerberos authentication to work when using WinRM, an SPN for the service must be registered in AD. As an example, you can find all of the "WSMAN" SPNs currently registered in your forest with this command:

setspn -T yourForest -F -Q WSMAN/*

SPN creation for this should be taken care of automatically, but you know something is wrong (and Kerberos will not be used) if there is no WSMAN SPN for the device that is hosting the WinRM service.

As with last time, when I execute the command on DC01:

$creds = Get-Credential
$server1 = New-PSSession -ComputerName SERVER1 -Credential $creds -Authentication "Negotiate"

A persistent remote connection is made from DC01 to SERVER1 via WinRM.

The following excerpt from this MSDN article is a pretty good description of what's going on. I'll recap, poorly:

  1. The nodes do a classic TCP/IP handshake. (ACK, SYN-ACK, NICE-TO-MEET-YOU-ACK)
  2. Client (DC01) does an HTTP Get for the resource. (Hey can I just access you?)
  3. Server (SERVER1) says "No way, I'm not that easy! (Returns 401 Unauthorized) ... but I am willing to negotiate, here's what I can do..."
  4. Client evaluates the authentication methods on offer, and sends new token with new base64-encoded authentication junk in it.
  5. Server accepts the challenge response by checking the hash against what it has in its own SAM, and allows Client to connect. (Returns HTTP 200)

So like I said, this communication is already pretty well protected. But maybe you want more. You can either set up an IPsec tunnel between the nodes, or you can enable certificate-based SSL encryption between the two nodes if you feel the need to further wrap all your packets in a warm blanket of security. We'll discuss certificate-based SSL encryption here.

First off, remember from Part I that WinRM just won't work with self-signed certificates. So we need a Certificate Authority. Luckily I've got one, but it's an ECA that belongs to a domain of which SERVER1 is not a member. No matter - to issue certificates to non-trusted parties, you simply need to add the web-enrollment junk to your ECA:

Add all of the web role services

I chose "Username and Password" authentication, but Integrated Windows Authentication might have worked as well, since the two computers are on the same network.

The next thing I'm going to do is install the certificate from the ECA into the Trusted Root CA store on SERVER1, so that SERVER1 will implicitly trust any certificate issued by my ECA. Export the certificate from the ECA, move the certificate to SERVER1, then Import the certificate to the correct store, you know the drill. You could also just browse to http://your-ECA/certsrv and download the CA certificate from there. Whatever works for you.

This next part gave me so much heartburn, and I'm hoping I can now save you some. You might remember from the first part of this tutorial that WinRM needs a certificate for "Server Authentication" purposes. The "Web Server" template in a basic set up of Certificate Services is for Server Authentication purposes. So we should just be able to use that one, right?

No one tells you this, but for WinRM to use the certificate, the private key must be marked as exportable when you request it from the CA. However, the original "Web Server" certificate template does not allow exporting private keys. So on your ECA, copy the Web Server template. Make sure you choose the "Windows Server 2003" option and not the "Server 2008" option, or else the new template will not show up in the drop-down menu on your Certsrv webpage. Name the copy something like "Web Server With Private Key." Modify the new template, and on the "Request Handling" tab, click "Allow private key to be exported." Nothing else needs to be changed unless you need to. Then, on the "Certificate Templates" node under your ECA, right click it, select New -> Certificate Template to Issue, and choose the new "Web Server with Private Key" template that you just created.

This article came in handy for me.

Next, on SERVER1, launch Internet Explorer. Make sure that the URL http://your-ECA/certsrv is added to SERVER1's Trusted Sites list, and modify your Internet Explorer security settings as needed so that you're able to run any and all ActiveX scripts that the ECA wants you to run, etc. Now browse to http://your-ECA/certsrv. You should need to provide credentials. (I bet it's through the same SPNEGO process that we witnessed earlier!) Make sure that the credentials you log in with have permissions to enroll in the certificate you will be requesting. You should get a pretty plain web page where you can request a certificate. If you don't, you've already gone astray.

Click on Request a Certificate, then submit an advanced certificate request. Then click Create and submit a request to this CA. Choose the "Web Server With Private Key" Certificate Template from the drop down menu that you created earlier. Yes, I know this is not a web server, but recall from part one of this tutorial that we need a certificate for "Server Authentication" purposes, and this certificate will give us that. You can spend a bunch of time playing around with the certrqtp.inc file on your CA and customizing the certificate request webpage to provide new templates if you want, but I don't really care about that right now. Also pay attention that as you change the certificate request type in the drop-down menu, you should be seeing the text boxes on the web page change around. This means the ActiveX junk is running successfully in the background.

So submit that request, and the website will either tell you that your certificate request requires approval (go approve it,) or it'll just give it to you right away, depending on the policy you set up on your CA. When you click the link to install your new certificate, the webpage will automatically install your new cert in your Current User > Personal store. Go look at it. It's important that it has the correct name on it (the subject and "CN=" part of the certificate needs to say SERVER1, etc.) and that there are no other validation errors. It should have "Server Authentication" in the Enhanced Key Usage field. Now they say that WinRM should be able to use this certificate whether it resides in the current user store or in the local computer store, but I had to export the certificate from there (including private key!) and then import it into the Local Computer > Personal store to get it to work. Finally, while you're here, open the properties of the certificate, and copy the Thumbprint. You'll need that in a second. (Reference)

Next, delete your old HTTP listener on SERVER1 with this command:

winrm delete winrm/config/Listener?Address=*+Transport=HTTP

You can only have one listener per network interface, from what I understand. Better we keep the config as simple as possible in any case. By the way, you can execute non-Powershell commands like this from within Powershell if you start the command with an ampersand. (& winrm delete winrm/config...)

Create your new HTTPS listener, configured to use your specified certificate, like this:

winrm create winrm/config/Listener?Address=*+Transport=HTTPS @{Hostname="SERVER1";CertificateThumbprint="1d9256aea461788764cec1904463120f094393f9"}

Where CertificateThumbprint is the thumbprint you copied off of the certificate a minute ago. If all goes well, you will get a "ResourceCreated" response from WinRM. Otherwise, the errors you are likely to see include "Cannot create a WinRM listener on HTTPS because this machine does not have an appropriate certificate. To be used for SSL, a certificate must have a CN matching the hostname, be appropriate for Server Authentication, and not be expired, revoked, or self-signed" or "A specified logon session does not exist. It may already have been terminated." I wrestled with both of those errors, and the only way I've gotten past them is to follow my above steps to the letter.

SERVER1 is now listening on port 5986, waiting for an SSL-protected connection. Keep in mind that since you didn't use quickconfig, it didn't automatically create a Windows Firewall rule for TCP 5986.

And finally - the fruit of our labor... So I've moved back to DC01. Keep in mind that DC01 is already configured to trust certificates that were issued by my ECA. I run this in Powershell:

$creds = Get-Credential
$server1 = New-PSSession SERVER1 -UseSSL -Credential $creds

And magic happens. And by "magic," I mean "no errors!" The connection established successfully with no fuss. And here's the cool part: This is a packet capture of the exact moment when the two nodes start communicating:

I don't even get to see the headers any more. It's all 100% complete gibberish, impervious to prying eyes, thanks to SSL encryption.

One last thing as a bonus for making it all the way through this article: In case you didn't know, Powershell creates "pseudo-drives," for lack of a better term, for certain repositories on your computer. For instance, in Powershell, type "cd cert:" to navigate around your Certificate Stores like a normal directory, and type "cd wsman:" to navigate around your WinRM configuration as if it were a regular file structure! Pretty cool, eh?

Monitoring with Windows Remote Management (WinRM) and Powershell Part I

Hey guys. I should have called this post "Monitoring with Windows Remote Management (WinRM), and Powershell, and maybe a Certificate Services tutorial too," but then the title would have definitely been too long. In any case, I poured many hours of effort and research into this one. Lots of trial and error. And whether it helps anyone else or not, I definitely bettered myself through the creation of this post.

I'm pretty excited about this topic. This foray into WinRM and Powershell Remoting was sparked by a conversation I had with a coworker the other day. He's a senior Unix engineer, so he obviously enjoys *nix and when presented with a problem, naturally he approaches it with the mindset of someone very familiar with and ready to use Unix/Linux tools.

I'm the opposite of that - I feel like Microsoft is the rightful king of the enterprise and usually approach problems with Windows-based solutions already in mind. But what's important is that we're both geeks and we'll both still happily delve into either realm when it presents an interesting problem that needs solving. There's a mutual respect there, even though we don't play with the same toys.

The Unix engineer wants to monitor all the systems using SNMP because it's tried and true and it's been around forever, and it doesn't require an agent or expensive third-party software. SNMP wasn't very secure or feature-rich at first so now they're on SNMPv3. Then there's WBEM. Certain vendors like HP have their own implementations of WBEM. I guess Microsoft wasn't in love with either and so decided to go their own way, as Microsoft is wont to do, hence why you won't find an out of the box implementation of SNMPv3 from Microsoft.

One nice thing about SNMP though, is that it uses one static, predictable port.

In large enterprise IT infrastructures, you're likely to see dozens of sites, hundreds (if not thousands,) of subnets, sprinklings of Windows and Unix devices all commingled together... and you can't swing a dead cat without hitting a firewall which may or may not have some draconian port restrictions on it. Furthermore, in a big enterprise you're likely to see the kind of bureaucracy and separation of internal organizations such that server infrastructure guys can't just go and reconfigure firewalls on their own, network guys can't just make changes without running it by a "change advisory board" first, and it all basically just makes you want to pull your hair out while you wait... and wait, and wait some more. You just want to be able to communicate with your other systems, wherever they are.

Which brings us to WinRM and Powershell Remoting. WinRM, a component of Windows Hardware Management, is Microsoft's implementation of the multi-platform, industry-standard WS-Management protocol. (Like WMI is Microsoft's implementation of WBEM. Getting tired of the acronym soup yet? We're just getting started. You might also want to review WMI Architecture.) I used WinRM in a previous post, but only used the "quickconfig" option. Seems like most people rarely go any deeper than the quickconfig parameter.

Here's an excerpt from a Technet doc:

"WinRM is Microsoft's implementation of the WS-Management protocol, a standard Simple Object Access Protocol (SOAP)-based, firewall-friendly protocol that enables hardware and operating systems from different vendors to interoperate. You can think of WinRM as the server side and WinRS the client side of WS-Management."

I bolded the phrase that especially made my ears perk up. You see, Windows has a long history with things like RPC and DCOM. Those protocols have been instrumental in many awesome distributed systems and tool sets throughout Microsoft's history. But it just so happens that these protocols are also probably the most complex, and most firewall unfriendly protocols around. It's extremely fortuitous then that Ned over at AskDS just happened to write up a magnificent explication of Microsoft RPC. (Open that link in a background tab and read it after you're done here.)

Here's the thing - what if I want to remotely monitor or interact with a machine in another country, or create a distributed system that spans continents? There are dozens of patchwork networks between the systems. Each packet between the systems traverses firewall after firewall. Suddenly, protocols such as RPC are out the window. How am I supposed to get every firewall owner from here to Timbuktu to let my RPC and/or DCOM traffic through?

That's why monitoring applications like SCOM or NetIQ AppManager require the installation of agents on the machines. They collect the data locally and then ship it to a central management server using just one or two static ports. Well, they do other more complex stuff too that requires software be installed on the machine, but that's beside the point.

Alright, enough talk. Let's get to work on gathering performance metrics remotely from a Windows server. There are a few scenarios to test here. One is communications within the boundaries of an Active Directory domain, and the other is communications with an external, non-domain machine. Then, exploring SSL authentication and encryption.

The first thing you need to do is set up and configure the WinRM service. One important thing to remember is that just starting the WinRM service isn't enough - you still have to explicitly create a listener. In addition, like most things SSL, it requires a certificate to properly authenticate and encrypt data. Run: 

winrm get winrm/config

to see the existing default WinRM configuration:

WinRM originally used ports 80 for HTTP and 443 for HTTPS. With Win7 and 2k8R2, it has changed to use ports 5985 and 5986 respectively. But those are just defaults and you can change the listener(s) back to the old ports if you want. Or any port for that matter. Run:

winrm enumerate winrm/config/listener

to list the WinRM listeners that are running. You should get nothing, because we haven't configured any listeners yet. WinRM over SSL will not work with a self-signed certificate. It has to be legit. From support.microsoft.com:

"WinRM HTTPS requires a local computer "Server Authentication" certificate with a CN matching the hostname, that is not expired, revoked, or self-signed to be installed."

To set up a WinRM listener on your machine, you can run

winrm quickconfig

or

winrm quickconfig -transport:HTTPS

or even

winrm create winrm/config/listener?Address=*+Transport=HTTPS @{Port="443"}

Use "set" instead of "create" if you want to modify an existing listener. The @{} bit at the end is called a hash table and can be used to pass multiple values. The WinRM.cmd command line tool is actually just a wrapper for winrm.vbs, a VB script. The quickconfig stuff just runs some script that configures and starts the listener, starts and sets the WinRM service to automatic, and creates some Windows Firewall exceptions. What is more is that Powershell has many cmdlets that use WinRM, and the entire concept of Powershell Remoting uses WinRM. So now that you know the fundamentals of WinRM and what's going on in the background, let's move ahead into using Powershell. In fact, you can emulate all of the same behavior of "winrm quickconfig" by instead running 

Configure-SMRemoting.ps1

from within Powershell to set up the WinRM service. Now from another machine, fire up Powershell and try to use the WinRM service you just set up:

$dc01 = New-PSSession -ComputerName DC01
Invoke-Command -Session $dc01 -ScriptBlock { gwmi win32_computersystem }

Returns:

You just pulled some data remotely using WinRM! The difference between using a "session" in Powershell, and simply executing cmdlets using the -ComputerName parameter, is that a session persists such that you can run multiple different sets of commands that all share the same data. If you try to run New-PSSession to connect to a computer on which you have not configured the WinRM service, you will get a nasty red error. You can also run a command on many machines simultaneously, etc. Hell, it's Powershell. You can do anything.

Alright so that was simple, but that's because we were operating within the safe boundaries of our Active Directory domain and all the authentication was done in the background. What about monitoring a standalone machine, such as SERVER1?

My first test machine:

  • Hostname: SERVER1 
  • IP: 192.168.1.10 
  • OS: Windows 2008 R2 SP1, fully patched, Windows Firewall is on
  • It's not a member of any domain

First things first: Launch Powershell on SERVER1. Run:

Set-ExecutionPolicy Unrestricted

Then set up your WinRM service and listener by running

Configure-SMRemoting.ps1

and following the prompts. If the WinRM server (SERVER1) is not in your forest (it's not) or otherwise can't use Kerberos, then HTTPS/SSL must be used, or the destination machine must be added to the TrustedHosts configuration setting. Let's try the latter first. On your client, add the WinRM server to the "Trusted Hosts" list:

We just authenticated and successfully created a remote session to SERVER1 using the Negotiate protocol! Negotiate is basically "use Kerberos if possible, fall back to NTLM if not." So the credentials are passed via NTLM, which is not clear text, but it's not awesome either. You can find a description of the rest of the authentication methods here, about halfway down the page, if you need a refresher.

Edit 1/29/2012: It should be noted that even within a domain, for Kerberos authentication to work when using WinRM, an SPN for the service must be registered in AD. As an example, you can find all of the "WSMAN" SPNs currently registered in your forest with this command:

setspn -T yourForest -F -Q WSMAN/*

SPN creation for this should have been taken care of automatically, but you know something is wrong (and Kerberos will not be used) if there is no WSMAN SPN for the device that is hosting the WinRM service.

OK, I am pooped. Time to take a break. Next time in Part II, we're going to focus on setting up SSL certificates to implement some real security to wrap up this experiment!

Auditing Active Directory Inactive Users with Powershell and Other Cool Stuff

Hello again, fellow wanderers.

I was having a hell of a comment spam problem here for a couple days... hope I didn't accidentally delete any legitimate comments in the chaos. (Read this excellent comment left on my last DNS post.) Then I realized that I might ought to change the challenge question and response for my simple captcha from its default... I guess the spammers have the old "5+5=" question figured out. :P

A few years ago, I made my own simple captcha for another blog that was along the lines of x + y = ? using PHP, but x and y were randomly generated at each page load. Worked really well. The simple captcha that comes boxed with BlogEngine.NET here is static. Being able to load a random question and answer pair from a pool of questions would be a definite enhancement.

Anyway, since we're still on the topic of auditing Active Directory, I've got another one for you: Auditing "inactive" user accounts.

I had a persnickety customer that wanted to be kept abreast of all AD user accounts that had not logged on in exactly 25 days or more. As soon as one delves into this problem, one might realize that a command-line command such as dsquery user -inactive x will display users that are considered inactive for x number of weeks, but not days. I immediately suspected that there must be a reason for that lack of precision, as I knew that any sort of computer geek/engineer that wrote the dsquery utility would not have purposely left out that measure of granularity unless there was a good reason for it.

So what defines an "inactive" user? A user that has not logged on to his or her user account in a period of time. There is an AD attribute on each user called LastLogonTimeStamp. After a little research, I stumbled across this post, where it is explained that the LastLogonTimeStamp attribute is not terribly accurate - i.e., off by more than a week. Now that dsquery switch makes a lot more sense. I conjecture that the LastLogonTimeStamp attribute is inaccurate because Microsoft had to make a choice when designing Active Directory - either have that attribute updated every single time a user account is logged on to and thus amplify domain replication traffic and work for the DCs, or have it only updated periodically and save the replication load.

To further complicate matters, there is an Active Directory Powershell cmdlet called Search-ADAccount that, when it returns users, it reports a LastLogonDate attribute. As it turns out, LastLogonDate is not even a real attribute, but rather that particular Powershell cmdlet's mechanism for translating LastLogonTimeStamp into a more human-readable form. (a .NET DateTime object.)

Next, there is another AD attribute - msDS-LogonTimeSyncInterval - that you can dial down to a minimum of 1 day, and that will have replication of the users' LastLogonTimeStamp attribute updated much more frequently and thus make it more accurate. Of course, this comes at the expense of additional load on the DCs and replication traffic. This may be negligible in a small domain, but may have a significant impact on a large domain.

*ADSI Edit*

Lastly, your other options for being able to accurately track the last logon time of users as close to "real-time" as possible involve scanning the security logs or attributes on all of your domain controllers and doing some heavy parsing. This is where event forwarding and subscriptions would really shine. See my previous post for details. I don't know about you guys, but all that sounds like a nightmare to me. Being able to track inactive user accounts to within 1 day is just going to have to suffice for now.

So we made the decision to decrease the msDS-LogonTimeSyncInterval, and I wrote this nifty Powershell script to give us the good stuff. Each major chunk of code is almost identical but with a minor tweak that represents the different use cases if given different parameters. Reading the comments toward the top on the five parameters will give you a clear picture of how the script works:

# ADUserAccountAudit.ps1
# Writen by Ryan Ries on Jan 19 2012
# Requires the AD Powershell Module which is on 2k8R2 DCs and systems with RSAT installed.
#
# Locates "inactive" AD user accounts. Note that LastLogonTimeStamp is not terribly accurate.
# Accounts that have never been logged into will show up as having a LastLogonTimeStamp of some time
# around 1600 AD - 81 years after the death of Leonardo da Vinci.
# This is because even though their LastLogonTimeStamp attribute is null, we cast it to a DateTime object
# regardless, which converts null inputs into a minimum date, apparently.
#
# For specific use with NetIQ AppManager, put this script on the agent machine at 
# C:\Program Files (x86)\NetIQ\AppManager\bin\Powershell (for 64 bit Windows. Just "Program Files" if 32 bit Windows.)

Param([string]$DN = "dc=corpdom,dc=local",         # LDAP distinguished name for domain
      [string]$domainName = "Corpdom",             # This can be whatever you want it to be
      [int]$inactiveDays = 25,                     # Users that have not logged on in this number of days will appear on this report
      [bool]$includeDisabledAccounts = $false,     # Setting this to true will include accounts that are already disabled in the report as well
      [bool]$includeNoLastLogonAccounts = $false)  # Setting this to true will include accounts that have never been logged into and thus have no LastLogonTimeStamp attribute.

# First, load the Active Directory module if it is not already loaded
$ADmodule = Get-Module | Where-Object { $_.Name -eq "activedirectory" } | Foreach { $_.Name }
if($ADmodule -ne "activedirectory")
{
   Import-Module ActiveDirectory
}

if($includeDisabledAccounts -eq $false)
{
   if($includeNoLastLogonAccounts -eq $false)
   {
      Write-Host "Enabled users that have not logged into $domainName in $inactiveDays days`r`nExcluding accounts that have never been logged into`r`nAccounts younger than $inactiveDays days not shown.`r`n-------------------------------------------------------"
      Search-ADAccount -UsersOnly -SearchBase "$DN" -AccountInactive -TimeSpan $inactiveDays`.00:00:00 | 
      Where-Object {$_.Enabled -eq $true -And $_.LastLogonDate -ne $null } |
      Get-ADUser -Properties Name, sAMAccountName, givenName, sn, lastLogonTimestamp, Enabled, WhenCreated |
      Where-Object {$_.WhenCreated -lt (Get-Date).AddDays(-$($inactiveDays)) } |
      Select sAMAccountName, givenName, sn, @{n="LastLogonTimeStamp";e={[DateTime]::FromFileTime($_.LastLogonTimestamp)}}, Enabled, WhenCreated |
      Sort-Object LastLogonTimeStamp |
      Format-Table   
   }
   else
   {
      Write-Host "Enabled users that have not logged into $domainName in $inactiveDays days`r`nIncluding accounts that have never been logged into`r`nAccounts younger than $inactiveDays days not shown.`r`n-------------------------------------------------------"
      Search-ADAccount -UsersOnly -SearchBase "$DN" -AccountInactive -TimeSpan $inactiveDays`.00:00:00 | 
      Where-Object {$_.Enabled -eq $true } |
      Get-ADUser -Properties Name, sAMAccountName, givenName, sn, lastLogonTimestamp, Enabled, WhenCreated |
      Where-Object {$_.WhenCreated -lt (Get-Date).AddDays(-$($inactiveDays)) } |
      Select sAMAccountName, givenName, sn, @{n="LastLogonTimeStamp";e={[DateTime]::FromFileTime($_.LastLogonTimestamp)}}, Enabled, WhenCreated |
      Sort-Object LastLogonTimeStamp |
      Format-Table 
   }
 
}
else
{
   if($includeNoLastLogonAccounts -eq $false)
   {
      Write-Host "All users that have not logged into $domainName in $inactiveDays days`r`nExcluding accounts that have never been logged into`r`nAccounts younger than $inactiveDays days not shown.`r`n------------------------------------------------------"   
      Search-ADAccount -UsersOnly -SearchBase "$DN" -AccountInactive -TimeSpan $inactiveDays`.00:00:00 |
      Where-Object { $_.LastLogonDate -ne $null } |
      Get-ADUser -Properties Name, sAMAccountName, givenName, sn, lastLogonTimestamp, Enabled, WhenCreated |
      Where-Object { $_.WhenCreated -lt (Get-Date).AddDays(-$($inactiveDays)) } |
      Select sAMAccountName, givenName, sn, @{n="LastLogonTimeStamp";e={[DateTime]::FromFileTime($_.lastlogontimestamp)}}, Enabled, WhenCreated |
      Sort-Object LastLogonTimeStamp |
      Format-Table   
   }
   else
   {
      Write-Host "All users that have not logged into $domainName in $inactiveDays days`r`nIncluding accounts that have never been logged into`r`nAccounts younger than $inactiveDays days not shown.`r`n------------------------------------------------------"   
      Search-ADAccount -UsersOnly -SearchBase "$DN" -AccountInactive -TimeSpan $inactiveDays`.00:00:00 |
      Get-ADUser -Properties Name, sAMAccountName, givenName, sn, lastLogonTimestamp, Enabled, WhenCreated |
      Where-Object {$_.WhenCreated -lt (Get-Date).AddDays(-$($inactiveDays)) } |
      Select sAMAccountName, givenName, sn, @{n="LastLogonTimeStamp";e={[DateTime]::FromFileTime($_.lastlogontimestamp)}}, Enabled, WhenCreated |
      Sort-Object LastLogonTimeStamp |
      Format-Table   
   }
}

So there you have it, a quick and dirty report to locate users that have been inactive for over x days. Accounts that were just created and not logged on to yet would have a LastLogonTimeStamp of null and would therefore show up in this report, so I threw the Where-Object {$_.WhenCreated -lt (Get-Date).AddDays(-$($inactiveDays)) } bit in there to exclude in any case the user accounts that were younger than the specified number of days required to consider an account "inactive." Furthermore, you might want to resist the urge just now to go a step further and programmatically disable inactive user accounts. Most organizations use service accounts and other special accounts that may not get logged into very often, and yet, all hell would break loose if you disabled them. I'm considering a system that disables the accounts, but also reads in a list of accounts which are "immune" and would therefore be ignored by the program. For a future post I guess.

Lastly, I want to thank Ned of the AskDS blog, without whom this post would not have been possible. (Now it sounds like a Grammy speech...) But seriously, I asked him about this stuff and he knew all the answers right away. Helped me out immeasurably on this.