How to get the groups of a user in Active Directory? (c#, asp.net)

I use this code to get the groups of the current user. But I want to manually give the user and then get his groups. How can I do this?

using System.Security.Principal;

public ArrayList Groups()
{
    ArrayList groups = new ArrayList();

    foreach (IdentityReference group in System.Web.HttpContext.Current.Request.LogonUserIdentity.Groups)
    {
        groups.Add(group.Translate(typeof(NTAccount)).ToString());
    }

    return groups;
}

If you're on .NET 3.5 or up, you can use the new System.DirectoryServices.AccountManagement (S.DS.AM) namespace which makes this a lot easier than it used to be.

Read all about it here: Managing Directory Security Principals in the .NET Framework 3.5

Update: older MSDN magazine articles aren't online anymore, unfortunately - you'll need to download the CHM for the January 2008 MSDN magazine from Microsoft and read the article in there.

Basically, you need to have a "principal context" (typically your domain), a user principal, and then you get its groups very easily:

public List<GroupPrincipal> GetGroups(string userName)
{
   List<GroupPrincipal> result = new List<GroupPrincipal>();

   // establish domain context
   PrincipalContext yourDomain = new PrincipalContext(ContextType.Domain);

   // find your user
   UserPrincipal user = UserPrincipal.FindByIdentity(yourDomain, userName);

   // if found - grab its groups
   if(user != null)
   {
      PrincipalSearchResult<Principal> groups = user.GetAuthorizationGroups();

      // iterate over all groups
      foreach(Principal p in groups)
      {
         // make sure to add only group principals
         if(p is GroupPrincipal)
         {
             result.Add((GroupPrincipal)p);
         }
      }
   }

   return result;
}

and that's all there is! You now have a result (a list) of authorization groups that user belongs to - iterate over them, print out their names or whatever you need to do.

Update: In order to access certain properties, which are not surfaced on the UserPrincipal object, you need to dig into the underlying DirectoryEntry:

public string GetDepartment(Principal principal)
{
    string result = string.Empty;

    DirectoryEntry de = (principal.GetUnderlyingObject() as DirectoryEntry);

    if (de != null)
    {
       if (de.Properties.Contains("department"))
       {
          result = de.Properties["department"][0].ToString();
       }
    }

    return result;
}

Update #2: seems shouldn't be too hard to put these two snippets of code together.... but ok - here it goes:

public string GetDepartment(string username)
{
    string result = string.Empty;

    // if you do repeated domain access, you might want to do this *once* outside this method, 
    // and pass it in as a second parameter!
    PrincipalContext yourDomain = new PrincipalContext(ContextType.Domain);

    // find the user
    UserPrincipal user = UserPrincipal.FindByIdentity(yourDomain, username);

    // if user is found
    if(user != null)
    {
       // get DirectoryEntry underlying it
       DirectoryEntry de = (user.GetUnderlyingObject() as DirectoryEntry);

       if (de != null)
       {
          if (de.Properties.Contains("department"))
          {
             result = de.Properties["department"][0].ToString();
          }
       }
    }

    return result;
}

GetAuthorizationGroups() does not find nested groups. To really get all groups a given user is a member of (including nested groups), try this:

using System.Security.Principal

private List<string> GetGroups(string userName)
{
    List<string> result = new List<string>();
    WindowsIdentity wi = new WindowsIdentity(userName);

    foreach (IdentityReference group in wi.Groups)
    {
        try
        {
            result.Add(group.Translate(typeof(NTAccount)).ToString());
        }
        catch (Exception ex) { }
    }
    result.Sort();
    return result;
}

I use try/catch because I had some exceptions with 2 out of 200 groups in a very large AD because some SIDs were no longer available. (The Translate() call does a SID -> Name conversion.)

First of all, GetAuthorizationGroups() is a great function but unfortunately has 2 disadvantages:

1. Performance is poor, especially in big company's with many users and groups. It fetches a lot more data then you actually need and does a server call for each loop iteration in the result
2. It contains bugs which can cause your application to stop working 'some day' when groups and users are evolving. Microsoft recognized the issue and is related with some SID's. The error you'll get is "An error occurred while enumerating the groups"

Therefore, I've wrote a small function to replace GetAuthorizationGroups() with better performance and error-safe. It does only 1 LDAP call with a query using indexed fields. It can be easily extended if you need more properties than only the group names ("cn" property).

// Usage: GetAdGroupsForUser2("domain\user") or GetAdGroupsForUser2("user","domain")
public static List<string> GetAdGroupsForUser2(string userName, string domainName = null)
{
    var result = new List<string>();

    if (userName.Contains('\\') || userName.Contains('/'))
    {
        domainName = userName.Split(new char[] { '\\', '/' })[0];
        userName = userName.Split(new char[] { '\\', '/' })[1];
    }

    using (PrincipalContext domainContext = new PrincipalContext(ContextType.Domain, domainName))
        using (UserPrincipal user = UserPrincipal.FindByIdentity(domainContext, userName))
            using (var searcher = new DirectorySearcher(new DirectoryEntry("LDAP://" + domainContext.Name)))
            {
                searcher.Filter = String.Format("(&(objectCategory=group)(member={0}))", user.DistinguishedName);
                searcher.SearchScope = SearchScope.Subtree;
                searcher.PropertiesToLoad.Add("cn");

                foreach (SearchResult entry in searcher.FindAll())
                    if (entry.Properties.Contains("cn"))
                        result.Add(entry.Properties["cn"][0].ToString());
            }

    return result;
}

Within the AD every user has a property memberOf. This contains a list of all groups he belongs to.

Here is a little code example:

// (replace "part_of_user_name" with some partial user name existing in your AD)
var userNameContains = "part_of_user_name";

var identity = WindowsIdentity.GetCurrent().User;
var allDomains = Forest.GetCurrentForest().Domains.Cast<Domain>();

var allSearcher = allDomains.Select(domain =>
{
    var searcher = new DirectorySearcher(new DirectoryEntry("LDAP://" + domain.Name));

    // Apply some filter to focus on only some specfic objects
    searcher.Filter = String.Format("(&(&(objectCategory=person)(objectClass=user)(name=*{0}*)))", userNameContains);
    return searcher;
});

var directoryEntriesFound = allSearcher
    .SelectMany(searcher => searcher.FindAll()
        .Cast<SearchResult>()
        .Select(result => result.GetDirectoryEntry()));

var memberOf = directoryEntriesFound.Select(entry =>
{
    using (entry)
    {
        return new
        {
            Name = entry.Name,
            GroupName = ((object[])entry.Properties["MemberOf"].Value).Select(obj => obj.ToString())
        };
    }
});

foreach (var item in memberOf)
{
    Debug.Print("Name = " + item.Name);
    Debug.Print("Member of:");

    foreach (var groupName in item.GroupName)
    {
        Debug.Print("   " + groupName);
    }

    Debug.Print(String.Empty);
}
}

My solution:

UserPrincipal user = UserPrincipal.FindByIdentity(new PrincipalContext(ContextType.Domain, myDomain), IdentityType.SamAccountName, myUser);
List<string> UserADGroups = new List<string>();            
foreach (GroupPrincipal group in user.GetGroups())
{
    UserADGroups.Add(group.ToString());
}

In my case the only way I could keep using GetGroups() without any expcetion was adding the user (USER_WITH_PERMISSION) to the group which has permission to read the AD (Active Directory). It's extremely essential to construct the PrincipalContext passing this user and password.

var pc = new PrincipalContext(ContextType.Domain, domain, "USER_WITH_PERMISSION", "PASS");
var user = UserPrincipal.FindByIdentity(pc, IdentityType.SamAccountName, userName);
var groups = user.GetGroups();

Steps you may follow inside Active Directory to get it working:

> 1. Into Active Directory create a group (or take one) and under secutiry tab add "Windows Authorization Access Group" > 2. Click on "Advanced" button > 3. Select "Windows Authorization Access Group" and click on "View" > 4. Check "Read tokenGroupsGlobalAndUniversal" > 5. Locate the desired user and add to the group you created (taken) from the first step

This works for me

public string[] GetGroupNames(string domainName, string userName)
    {
        List<string> result = new List<string>();

        using (PrincipalContext principalContext = new PrincipalContext(ContextType.Domain, domainName))
        {
            using (PrincipalSearchResult<Principal> src = UserPrincipal.FindByIdentity(principalContext, userName).GetGroups())
            {
                src.ToList().ForEach(sr => result.Add(sr.SamAccountName));
            }
        }

        return result.ToArray();
    }

The answer depends on what kind of groups you want to retrieve. The System.DirectoryServices.AccountManagement namespace provides two group retrieval methods:

> [GetGroups][1] - Returns a collection of group objects that specify the groups of which the current principal is a member. > > This overloaded method only returns the groups of which the principal is directly a member; no recursive searches are performed. > > [GetAuthorizationGroups][2] - Returns a collection of principal objects that contains all the authorization groups of which this user is a member. This function only returns groups that are security groups; distribution groups are not returned. > > This method searches all groups recursively and returns the groups in which the user is a member. The returned set may also include additional groups that system would consider the user a member of for authorization purposes.

So GetGroups gets all groups of which the user is a direct member, and GetAuthorizationGroups gets all authorization groups of which the user is a direct or indirect member.

Despite the way they are named, one is not a subset of the other. There may be groups returned by GetGroups not returned by GetAuthorizationGroups, and vice versa.

Here's a usage example:

PrincipalContext domainContext = new PrincipalContext(ContextType.Domain, "MyDomain", "OU=AllUsers,DC=MyDomain,DC=Local");
UserPrincipal inputUser = new UserPrincipal(domainContext);
inputUser.SamAccountName = "bsmith";
PrincipalSearcher adSearcher = new PrincipalSearcher(inputUser);
inputUser = (UserPrincipal)adSearcher.FindAll().ElementAt(0);
var userGroups = inputUser.GetGroups();

[1]: https://docs.microsoft.com/en-us/dotnet/api/system.directoryservices.accountmanagement.principal.getgroups?redirectedfrom=MSDN&view=netframework-4.7.2#overloads "GetGroups" [2]: https://docs.microsoft.com/en-us/dotnet/api/system.directoryservices.accountmanagement.userprincipal.getauthorizationgroups?redirectedfrom=MSDN&view=netframework-4.7.2#System_DirectoryServices_AccountManagement_UserPrincipal_GetAuthorizationGroups "GetAuthorizationGroups"

In case Translate works locally but not remotly e.i group.Translate(typeof(NTAccount)

If you want to have the application code executes using the LOGGED IN USER identity, then enable impersonation. Impersonation can be enabled thru IIS or by adding the following element in the web.config.

<system.web>
<identity impersonate="true"/>

If impersonation is enabled, the application executes using the permissions found in your user account. So if the logged in user has access, to a specific network resource, only then will he be able to access that resource thru the application.

Thank PRAGIM tech for this information from his diligent video

Windows authentication in asp.net Part 87:

https://www.youtube.com/watch?v=zftmaZ3ySMc

But impersonation creates a lot of overhead on the server

The best solution to allow users of certain network groups is to deny anonymous in the web config <authorization><deny users="?"/><authentication mode="Windows"/>

and in your code behind, preferably in the global.asax, use the HttpContext.Current.User.IsInRole :

Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs)
If HttpContext.Current.User.IsInRole("TheDomain\TheGroup") Then
//code to do when user is in group
End If

NOTE: The Group must be written with a backslash \ i.e. "TheDomain\TheGroup"

This is quick and dirty but someone may find it helpful. You will need to add the reference to System.DirectoryServices.AccountManagement for this to work. This is just for getting user roles but can be expanded to include other things if needed.

using System.DirectoryServices.AccountManagement;

PrincipalContext ctx = new PrincipalContext(ContextType.Domain, "DaomainName");
UserPrincipal u = UserPrincipal.FindByIdentity(ctx, "Username");

List<UserRole> UserRoles = u.GetGroups().Select(x => new UserRole { Role = x.Name }).ToList();

public partial class UserRole
{
    public string Role { get; set; }
}