Finding If User Is A Member Of A Group

I want to find out by using C#, if a user is a member of an AD group but I am not able to get it to work? I have tried many examples on the net, can anyone help me out? Below is the code:

Code:

---

public void LookupUser()
{
bool UserExists = false;
string UserName = "FrankB@MadeUp.com";
string GroupName = "Europa No.1";
string strPath = "CN="+GroupName+",OU=SomeOU,DC=SomeName,DC=co,DC=uk";

DirectoryEntry userGroup = new DirectoryEntry(strPath);
DirectorySearcher searcher = new DirectorySearcher(userGroup);
//Set up the LDAP search filter
string strFilter =
String.Format("(&(objectCategory=person)(objectClass=user)(sAMAccountName={0}))", UserName);
searcher.Filter = strFilter;
SearchResult result = null;
if (searcher != null)
{
result = searcher.FindOne();
}
if(result != null)
for (int counter = 0; counter <
result.Properties["member"].Count; counter++)
{
string user = (string)result.Properties["member"][counter];
if(user.ToUpper()==UserName.ToUpper())
{
UserExists=true;
}
else
{
if(bool.Parse(UserExists.ToString())==true){}
else
{
UserExists=false;
}
}
}
}

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Code:

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public void LookupUser2 ()
{
string UserName = "FrankB@MadeUp.com";
string GroupName = "Europa No.1";
DirectoryEntry objADAM;
DirectoryEntry objGroupEntry;
DirectorySearcher objSearchADAM;
SearchResultCollection objSearchResults;
string strPath;

// Construct the binding string.
strPath = "CN="+GroupName+",OU=SomeOU,DC=SomeName,DC=co,DC=uk";

// Get the AD LDS object.
objADAM = new DirectoryEntry(strPath);
objADAM.RefreshCache();

// Get search object, specify filter and scope,
// perform search.
objSearchADAM = new DirectorySearcher(objADAM);
objSearchADAM.Filter = "(&(objectClass=group))";
objSearchADAM.SearchScope = SearchScope.Subtree;
objSearchResults = objSearchADAM.FindAll();

// Enumerate groups and members.
if (objSearchResults.Count != 0)
{
foreach(SearchResult objResult in objSearchResults)
{
objGroupEntry = objResult.GetDirectoryEntry();
Console.WriteLine("Group    {0}",
objGroupEntry.Name);
foreach(object objMember
in objGroupEntry.Properties["member"])
{
Console.WriteLine(" Member: {0}",
objMember.ToString());
}
}
}
else
{
Console.WriteLine("Results: No groups found.");
}
}

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I think that by using the System.DirectoryServices.AccountManagement namespace added in .NET 3.5 if it is available. Below is an example for group checking:

Code:

---

using(var pc = new PrincipalContext(ContextType.Domain))
using(var user = UserPrincipal.FindByIdentity(pc, IdentityType.SamAccountName, "DOMAIN\JDoe"))
using(var group = GroupPrincipal.FindByIdentity(pc, "FUNNY_USERS"))
{
    return user.IsMemberOf(group);
 }

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Well, if you want to check for group membership and if it is alright for you to test against the domain instead of against AD then you can simple use the below code:

Code:

---

bool IsInGroup(string user, string group)
{
    using (var identity = new WindowsIdentity(user))
    {
        var principal = new WindowsPrincipal(identity);
        return principal.IsInRole(group);
    }
}

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I think that you might be using the wrong API for the task you are doing. Do you intend to write an authentication code for an application? If yes then there must be a simple API that you can use. Like for instance, in ASP.NET, you can try to access this information using the Page.User object. Or else whether the purpose of the application is to query Active Directory?