Archive: Posts Tagged ‘PowerShell’

Prevent accidental deletions of AD objects

No comments June 5th, 2013

The “ask DS team” posted a blog post about “Two lines that can save your AD from a crisis”. Not a bad thing to do as it will prevent you or another admin to accidentally delete users or computer objects.

The lines they wrote protected users, computers and OUs. Did they forget about Groups?

Anyway, to also include all your groups:

# Set the "ProtectedFromAccidentalDeletion" attribute to "true" on all users,
# computers and groups in your domain where the attribute is set to "false"

Get-ADObject -filter {ObjectClass -eq "user" -or objectclass -eq "group"} -Properties ProtectedFromAccidentalDeletion | where {$_.ProtectedFromAccidentalDeletion -eq $false} | Set-ADObject -ProtectedFromAccidentalDeletion:$true

If you try to delete a user og computer object, you will get an error stating the object is protected from accidental deletion. You will have to untick the “Protect object from accidental deletion”:

pic1

 

What if you’d like to move the user object to a different OU? Same error as above. You must set the attribute to ‘false’.

If you have hundreds of objects in an OU you’d like to move, it’s easier to use Powershell to revert the attribute of all objects in the spesific OU:

Get-ADObject -SearchBase 'OU=OU1,dc=domain,dc=com' -filter {ObjectClass -eq "user" -or objectclass -eq "group"} -Properties ProtectedFromAccidentalDeletion | where {$_.ProtectedFromAccidentalDeletion -eq $true} | Set-ADObject -ProtectedFromAccidentalDeletion:$false

Will Gareth Bale stay with Spurs next season?

 

Reset the Secure Channel

No comments October 25th, 2011

When a computer joins a domain, a computer account is created in AD. The computer account gets its own password that will expire after 30 days (default). When the password expire, the computer itself will initiate a password change with a DC in its domain.

When the computer starts up, it uses this password to create a secure channel (SC) with a DC. The computer will request to sign all traffic that passes the SC. If a DC says “go ahead”, all traffic that is signed passes through this channel.

Traffic like NTLM pass through authentication is typically signed traffic.

So what will happen if there is a mismatch between the computer account password? The computer tries to authenticate, but the DC says this is not the correct password.

The SC is down.

Tools like “netdom” could be used to reset the password, but this only worked to reset the SC between two DCs. It was not possible to reset the SC on a domain member. The computer had to rejoin the domain.

Syntax:

netdom resetpwd /server:<Name of a DC> /userd:domain\administrator /passwordd:admin_password

Netdom was written back in the NT4 days, and a new tool has taken over. Not just taken over for Netdom, but also for tools like Nltest. Windows PowerShell.

To reset the SC between a computer and a DC:

Open PowerShell on the computer and run the *cmdlet:

Test-ComputerSecureChannel -repair

*The cmdlet requires PowerShell 2.0, which is pre-installed on Win7/2008R2.

In Win8 there are thousands of new cmdlets, so if you have not began to look at PS. Now is a good time.

 

References:

PowerShell 2.0 for XP, 2003, Vista, 2008: http://support.microsoft.com/kb/968929

Symptoms of a broken SC: http://blogs.technet.com/b/asiasupp/archive/2007/01/18/typical-symptoms-when-secure-channel-is-broken.aspx

Test-ComputerSecureChannel cmdlet: http://technet.microsoft.com/en-us/library/dd367893.aspx