How to retrieve Users in a Group, including primary group users

Question

I\'m working in .net 2.0 and need to retrieve all the users of a given AD group. I have the following method that does return all the members of the group, but it does not

Answer 1

The primary group of a user is given by primaryGroupID attribute of a user. In fact primaryGroupID contains the RID of the primary group in a string format. That's why, I first get the SID of the group you are looking for users, then I compute (badly) the RID, and I search for users with a primaryGroupID containing the RID.

/* Connection to Active Directory
 */
DirectoryEntry deBase = new DirectoryEntry("LDAP://WM2008R2ENT:389/dc=dom,dc=fr");

/* Directory Search for agroup
 */
string givenGrpName = "MonGrpSec"; 
DirectorySearcher dsLookFor = new DirectorySearcher(deBase);
dsLookFor.Filter = string.Format ("(sAMAccountName={0})", givenGrpName);
dsLookFor.SearchScope = SearchScope.Subtree;
dsLookFor.PropertiesToLoad.Add("cn");
dsLookFor.PropertiesToLoad.Add("objectSid");

SearchResult srcGrp = dsLookFor.FindOne();

/* Get the SID
 */
SecurityIdentifier secId = new SecurityIdentifier(srcGrp.Properties["objectSid"][0] as byte[], 0);

/* Find The RID (sure exists a best method)
 */
Regex regRID = new Regex(@"^S.*-(\d+)$");
Match matchRID =  regRID.Match(secId.Value);
string sRID = matchRID.Groups[1].Value;

/* Directory Search for users that has a particular primary group
 */
DirectorySearcher dsLookForUsers = new DirectorySearcher(deBase);
dsLookForUsers.Filter = string.Format("(primaryGroupID={0})", sRID);
dsLookForUsers.SearchScope = SearchScope.Subtree;
dsLookForUsers.PropertiesToLoad.Add("cn");

SearchResultCollection srcUsers = dsLookForUsers.FindAll();

foreach (SearchResult user in srcUsers)
{
  Console.WriteLine("{0} is the primary group of {1}", givenGrpName, user.Properties["cn"][0]);
}