Question

I’m using C# to find my local computer’s objectGuid by querying Active Directory. To do this, I’m currently using a DirectorySearcher, passing it a (hardcoded) path as the search root, and then filtering by computer name:

string adRootPath = @"LDAP://OU=foo,DC=bar,DC=baz,DC=com";    
DirectoryEntry adRoot = new DirectoryEntry(adRootPath);

DirectorySearcher searcher = new DirectorySearcher(adRoot);
searcher.Filter = @"(&(objectCategory=Computer)(CN=" + Environment.MachineName + "))";

I don’t want to hardcode the search root, and was wondering if there is a better way. I thought about just using an empty search root, but I was worried that computer names may not always be unique across different domains.

Is there a better way?

Answer 1

If you’re on .NET 3.5 or newer, you can use a PrincipalSearcher and a “query-by-example” principal to do your searching:

// create your domain context
PrincipalContext ctx = new PrincipalContext(ContextType.Domain);

// define a "query-by-example" principal - here, we search for a ComputerPrincipal 
// and with the name of "MyPC"
ComputerPrincipal cp = new ComputerPrincipal(ctx);
cp.Name = "MyPC";

// create your principal searcher passing in the QBE principal    
PrincipalSearcher srch = new PrincipalSearcher(cp);

// find all matches
foreach(var found in srch.FindAll())
{
    // do whatever here - "found" is of type "Principal" - it could be user, group, computer.....          
}

If you haven’t already – absolutely read the MSDN article Managing Directory Security Principals in the .NET Framework 3.5 which shows nicely how to make the best use of the new features in System.DirectoryServices.AccountManagement