Getting authenticate AD users objectGuid from asp.net

Question

Hi all

I am using windows authentication within an ASP.NET application. I am wondering how to best get the objectGuid from the currently logged in user?

Regards, Egil.

Answer 1

You can do this with the System.DirectoryServices namespace.

Dim entry As DirectoryServices.DirectoryEntry
Dim mySearcher As System.DirectoryServices.DirectorySearcher
Dim result As System.DirectoryServices.SearchResult
Dim myEntry As DirectoryEntry
Dim domainName As String
Dim userId As String
Dim objectGuid As Guid

'Split the username into domain and userid parts
domainName = Page.User.Identity.Name.Substring(0, Page.User.Identity.Name.IndexOf("\"))
userId = Page.User.Identity.Name.Substring(Page.User.Identity.Name.IndexOf("\") + 1)

'Start at the top level domain
entry = New DirectoryEntry(domainName)

mySearcher = New DirectorySearcher(entry)

'Build a filter for just the user
mySearcher.Filter = ("(&(anr=" & userId & ")(objectClass=user))")

'Get the search result ...
result = mySearcher.FindOne

'... and then get the AD entry that goes with it
myEntry = result.GetDirectoryEntry

'The Guid property is the objectGuid
objectGuid = myEntry.Guid

There might be a better way to do this, but this works!

Answer 2

You need to use NativeGuid property. C# code:

string login = HttpContext.Current.User.Identity.Name;
string domain = login.Substring(0, login.IndexOf('\\'));
string userName = login.Substring(login.IndexOf('\\') + 1);
DirectoryEntry domainEntry = new DirectoryEntry("LDAP://" + domain);
DirectorySearcher searcher = new DirectorySearcher(domainEntry);
searcher.Filter = string.Format(
   "(&(objectCategory=person)(objectClass=user)(sAMAccountName={0}))",
   userName);
SearchResult searchResult = searcher.FindOne();
DirectoryEntry entry = searchResult.GetDirectoryEntry();
Guid objectGuid = new Guid(entry.NativeGuid);

Answer 3

The suggest solutions are rather expensive. Rather than searching by domain and username, a better solution is to use the SID to lookup the account:

// using System.Security.Principal;
IPrincipal userPrincipal = HttpContext.Current.User;
WindowsIdentity windowsId = userPrincipal.Identity as WindowsIdentity;
if (windowsId != null)
{
    SecurityIdentifier sid = windowsId.User;

    using(DirectoryEntry userDe = new DirectoryEntry("LDAP://<SID=" + sid.Value + ">"))
    {
        Guid objectGuid = new Guid(userDe.NativeGuid);
    }
}