Duplicate SPNs aren’t very common but can happen in any Active Directory as there’s no built-in way that tracks and prevent duplicate SPN’s. One has to either know all SPN’s in the environment, track them or check each time whether it already exists or not. Things get more complicated with larger Active Directory environments as people change, new apps are added, old apps are forgotten, but SPNs prevail.
Active Directory Trusts are useful to connect one or more domains. But as useful those are, they can be very dangerous. Also, keeping trusts working and in good shape should be a top priority for Active Directory Admins. While there is a couple of command in the Active Directory module Get-ADTrust, I thought I would try and write my own that checks a few more things. I want to thank Chris Dent for his input on the part of this command. His binary skills amaze me!
In the Active Directory PowerShell module, you have two commands to your disposal that help display group membership. Those are Get-ADGroup and Get-ADGroupMember. The first command contains property Members, which gives you DistinguishedName of all members, and Get-ADGroupMember can provide you either direct members or with Recursive switch all members recursively (skipping groups). Till a few weeks ago, I was a happy user of those commands until I noticed two things. Member property for Get-ADGroup sometimes misses elements for whatever reason.
One of the critical parts of Active Directory is DFS. It allows you to share same NETLOGON/SYSVOL folders across all Domain Controllers in your Forest. Its health is vital to the functionality of your Active Directory. If it’s broken, a lot of things may not work, and it’s not that easy to tell the status of it. At first sight, everything may seem to work correctly, but if you take a closer look – not so much. It’s great if you find it out by yourself, but not fun if suddenly GPO’s don’t apply to some users, computers, and you find out a year later.
I’ve been in IT for a longer time now. I’ve made my fair share of mistakes and misconfigurations. One of those misconfigurations was removing Authenticated Users from Security filtering in Group Policy Objects. While it worked fine at some point Microsoft rolled out a Hotfix MS16-07 on June 14th 2016.
In March 2020, Microsoft will release its monthly updates. With those updates, Microsoft will disable insecure LDAP Bindings, which is going to break a lot of your systems (hopefully not). But this was already communicated, and you know all about it, right? If not, you should read those two articles that can help you with understanding what is happening and when.