See if user is part of Active Directory group in C# + Asp.net

Question

I need a way to see if a user is part of an active directory group from my .Net 3.5 asp.net c# application.

I am using the standard ldap authentication example off o

Answer 1

If you want to check the user groups membership including the nested groups which is indirectly linked to the user parent group you can try use the "tokenGroups" properties as below:

Using System.DirectoryServices

 public static bool IsMemberOfGroupsToCheck(string DomainServer, string LoginID, string LoginPassword)
        {
            string UserDN = "CN=John.Doe-A,OU=Administration Accounts,OU=User Directory,DC=ABC,DC=com"
            string ADGroupsDNToCheck = "CN=ADGroupTocheck,OU=Administration Groups,OU=Group Directory,DC=ABC,DC=com";

            byte[] sid, parentSID;
            bool check = false;
            DirectoryEntry parentEntry;
            DirectoryEntry basechildEntry;
            string octetSID;

                basechildEntry = new DirectoryEntry("LDAP://" + DomainServer + "/" + UserDN, LoginID, LoginPassword);
                basechildEntry.RefreshCache(new String[] { "tokenGroups" });

                parentEntry = new DirectoryEntry("LDAP://" + DomainServer + "/" + ADGroupsDNToCheck, LoginID, LoginPassword);
                parentSID = (byte[])parentEntry.Properties["objectSID"].Value;
                octetSID = ConvertToOctetString(parentSID, false, false);

                foreach(Object GroupSid in basechildEntry.Properties["tokenGroups"])
                {
                    sid = (byte[])GroupSid;
                    if (ConvertToOctetString(sid,false,false) == octetSID)
                    {
                        check = true;
                        break;
                    }
                }

                basechildEntry.Dispose();
                parentEntry.Dispose();

                return check;
        }