Get nETBIOSName from a UserPrincipal object

Question

I am using the System.DirectoryServices.AccountManagement part of the .Net library to interface into ActiveDirectory.

Having called GetMembers() on a GroupPrincipal object and filter the results, I now have a collection of UserPrincipal objects

GroupPrincipal myGroup;  // population of this object omitted here 

foreach (UserPrincipal user in myGroup.GetMembers(false).OfType<UserPrincipal>())
{
    Console.WriteLine(user.SamAccountName);
}

The above code sample will print out usernames like "TestUser1". I need to compare these to a list coming from another application in "DOMAIN\TestUser1" format.

How do I get the "DOMAIN" part from the UserPrincipal object?

I can't just append a known domain name as there are multiple domains involved and I need to differentiate DOMAIN1\TestUser1 and DOMAIN2\TestUser2.

@marc_s The UserPrincipleName contains the name in [email protected] format - I can't see how to easily convert that into DOMAIN\user format (especially as the domains involved are a known list - each production environment will be a different list of domains than my dev environment) — Grhm
You can also use the msDS-PrincipalName property as described here stackoverflow.com/questions/10702188 — Greg Bray
Or use user.Sid.Translate(typeof(System.Security.Principal.NTAccount)).ToString() to get the Domain\Username of each group member. See stackoverflow.com/questions/6759463 — Greg Bray
@GregBray msDs-Principalname did not exist in Win2003 for AD LDS systems (see msdn.microsoft.com/en-us/library/cc221208.aspx) and on AD DS may contain the NETBIOS name (see msdn.microsoft.com/en-us/library/cc223404.aspx). I no longer have access to the domains I originally had this problem with to check - but your suggestion may be useful to those that follow... — Grhm

Will Marcouiller Will Marcouiller · Accepted Answer · 2010-11-26T14:35:18

You have two choices that I can think of.

Parse, or take everything that is on, the right of [email protected];
Use the System.DirectoryServices namespace.

I don't know about UserPrincipal, neither do I about GroupPrincipal. On the other hand, I know of a working way to achive to what you want.

[TestCase("LDAP://fully.qualified.domain.name", "TestUser1")] 
public void GetNetBiosName(string ldapUrl, string login)
    string netBiosName = null;
    string foundLogin = null;

    using (DirectoryEntry root = new DirectoryEntry(ldapUrl))
        Using (DirectorySearcher searcher = new DirectorySearcher(root) {
            searcher.SearchScope = SearchScope.Subtree;
            searcher.PropertiesToLoad.Add("sAMAccountName");
            searcher.Filter = string.Format("(&(objectClass=user)(sAMAccountName={0}))", login);

            SearchResult result = null;

            try {
                result = searcher.FindOne();

                if (result == null) 
                    if (string.Equals(login, result.GetDirectoryEntry().Properties("sAMAccountName").Value)) 
                        foundLogin = result.GetDirectoryEntry().Properties("sAMAccountName").Value
            } finally {
                searcher.Dispose();
                root.Dispose();
                if (result != null) result = null;
            }
        }

    if (!string.IsNullOrEmpty(foundLogin)) 
        using (DirectoryEntry root = new DirectoryEntry(ldapUrl.Insert(7, "CN=Partitions,CN=Configuration,DC=").Replace(".", ",DC=")) 
            Using DirectorySearcher searcher = new DirectorySearcher(root)
                searcher.Filter = "nETBIOSName=*";
                searcher.PropertiesToLoad.Add("cn");

                SearchResultCollection results = null;

                try {
                    results = searcher.FindAll();

                    if (results != null && results.Count > 0 && results[0] != null) {
                        ResultPropertyValueCollection values = results[0].Properties("cn");
                        netBiosName = rpvc[0].ToString();
                } finally {
                    searcher.Dispose();
                    root.Dispose();

                    if (results != null) {
                        results.Dispose();
                        results = null;
                    }
                }
            }

    Assert.AreEqual("INTRA\TESTUSER1", string.Concat(netBiosName, "\", foundLogin).ToUpperInvariant())
}

Other related information or links available in this SO question.
C# Active Directory: Get domain name of user?
How to find the NetBIOS name of a domain

Get nETBIOSName from a UserPrincipal object

5 Answers