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How to keep my application "authenticated" with an AD account? c#

I am pretty new to C#
I have been using Powershell scripts to code things like Unlocking an AD user or Enabling/Disabling an account. however, I do this with a different account, so I will log in with the admin account (Get-Credential) and storing it as '$cred' for example.
I am currently trying to do a similar thing in C# and I have found how to effectively "Authenticate"
But I am not sure how to store that Authentication, or have my app Authenticated to do things with it like Disable or Unlock an AD Account.
I have this:
public bool ADauthenticate(string username, string password)
{
bool result = false;
using (DirectoryEntry _entry = new DirectoryEntry())
{
_entry.Username = username;
_entry.Password = password;
DirectorySearcher _searcher = new DirectorySearcher(_entry);
_searcher.Filter = "(objectclass=user)";
try
{
SearchResult _sr = _searcher.FindOne();
string _name = _sr.Properties["displayname"][0].ToString();
MessageBox.Show("authenticated!");
result = true;
this.Close();
}
catch
{
MessageBox.Show("Incorrect credentials");
this.ADUsername.Text = "";
this.ADPwd.Text = "";
}
}
return result; //true = user Authenticated.
}
Which just tells me that the account is correct of course, but doesn't keep my application "authenticated", any ideas?

It's not accurate to say that your "application" was authenticated. All that was authenticated is a single network connection to your domain controller. As soon as _entry is destroyed, you lose that authentication.
If you want everything to happen using those credentials, then you have several options, ranging from easy (for you) to more difficult:
Have your users run your application under the credentials they need. Then you don't need to bother getting their username and password or setting the username and password on the DirectoryEntry object. Users can do this by:
Using Shift + right-click on the application icon and click "Run as a different user", or
Create a shortcut to: runas.exe /user:DOMAIN\username "yourapplication.exe". This will open a command window asking for the password, then start your application under those credentials.
You still ask for the username and password, but restart your application under those credentials using Process.Start().
Keep the username and password variables alive for the life of the application and pass them to every DirectoryEntry object you create in your application.
Options 1 and 2 require the computer that you're running this from is joined to the same or trusted domain as the domain you are connecting to. But since I see you're not specifying the domain name, I'm guessing that's the case.

You can do this a lot easier by using the System.DirectoryServices.AccountManagement assembly and namespace.
Add a reference to the System.DirectoryServices.AccountManagement assembly to your project, and then use this code to validate username/password against AD:
using System.DirectoryServices.AccountManagement;
// create the principal context
using (PrincipalContext ctx = new PrincipalContext(ContextType.Domain, "YourDomain"))
{
bool accountValidated = ctx.ValidateCredentials(userName, password);
// do whatever you want to do with this information
}

Get AD users and groups from client

Is there any way possible to access a clients AD users and groups outsite an intranet setting?
I am not looking for azure solutions.
The tech i am working with is .Net Core web api and Angular as frontend.
Retrieving AD information on my own domain is achievable and i could get UserPrincipals,
but if the web API and AD is not hosted on the same server, how does that work?

I can't tell you exactly how to do it, since I haven't done it with .NET Core yet, but I can tell you what you need to do and you can look up more details about each part.
Use forms authentication. You will need a login page that asks for their username and password.
Validate the credentials. There are several ways to do this. My favourite is in this answer, which uses LdapConnection from System.DirectoryServices.Protocols because it's the least amount of network requests needed to do the job and it will tell your why credentials fail (which would let you take the user to a "change password" page if their password has expired, for example). However, using DirectoryEntry/DirectorySearcher is easier for looking up groups, so you might want to also use that for validating too, by using the user's credentials in the constructor of DirectoryEntry (but you'd lose knowing the reason for failed attempts).
Look up the user's account. I prefer using DirectoryEntry/DirectorySearcher from System.DirectoryServices for this. Eldar's answer shows how to do that.
Find the user's groups. I wrote a whole article about this: Finding all of a user's groups. Assuming you only have one domain in your environment, and you already have a DirectoryEntry object for the user's account, this code will work:
private static IEnumerable<string> GetUserMemberOf(DirectoryEntry de) {
var groups = new List<string>();
//retrieve only the memberOf attribute from the user
de.RefreshCache(new[] {"memberOf"});
while (true) {
var memberOf = de.Properties["memberOf"];
foreach (string group in memberOf) {
var groupDe = new DirectoryEntry($"LDAP://{group.Replace("/", "\\/")}");
groupDe.RefreshCache(new[] {"cn"});
groups.Add(groupDe.Properties["cn"].Value as string);
}
//AD only gives us 1000 or 1500 at a time (depending on the server version)
//so if we've hit that, go see if there are more
if (memberOf.Count != 1500 && memberOf.Count != 1000) break;
try {
de.RefreshCache(new[] {$"memberOf;range={groups.Count}-*"});
} catch (COMException e) {
if (e.ErrorCode == unchecked((int) 0x80072020)) break; //no more results
throw;
}
}
return groups;
}
If you have more than one domain in your environment, then it'll be a bit more complicated.

var entry = new DirectoryEntry("LDAP://DC=DomainController,DC=com","UserName","P4$$w0Rd!???");
// userName password must be valid
var searcher = new DirectorySearcher(entry);
searcher.PropertiesToLoad.Add("sn");
var accName = "accNameToSearch"; // you can also use wildcart
// https://learn.microsoft.com/en-us/windows/win32/adsi/search-filter-syntax
searcher.Filter = $"(&(objectCategory=person)(objectClass=user)(sAMAccountName={accName}))";
var result = searcher.FindOne();
var sn = result.Properties["sn"];
There is no UserPrincipal class for that nuget package yet. But you can still query users and other stuff with ad query syntax like above.

LDAP search fails on server, not in Visual Studio

I'm creating a service to search for users in LDAP. This should be fairly straightforward and probably done a thousand times, but I cannot seem to break through properly. I thought I had it, but then I deployed this to IIS and it all fell apart.
The following is setup as environment variables:
ldapController
ldapPort
adminUsername 🡒 Definitely a different user than the error reports
adminPassword
baseDn
And read in through my Startup.Configure method.
EDIT I know they are available to IIS, because I returned them in a REST endpoint.
This is my code:
// Connect to LDAP
LdapConnection conn = new LdapConnection();
conn.Connect(ldapController, ldapPort);
conn.Bind(adminUsername, adminPassword);
// Run search
LdapSearchResults lsc = conn.Search(
baseDn,
LdapConnection.SCOPE_SUB,
lFilter,
new string[] { /* lots of attributes to fetch */ },
false
);
// List out entries
var entries = new List<UserDto>();
while (lsc.hasMore() && entries.Count < 10) {
LdapEntry ent = lsc.next(); // <--- THIS FAILS!
// ...
}
return entries;
As I said, when debugging this in visual studio, it all works fine. When deployed to IIS, the error is;
Login failed for user 'DOMAIN\IIS_SERVER$'
Why? The user specified in adminUsername should be the user used to login (through conn.Bind(adminUsername, adminPassword);), right? So why does it explode stating that the IIS user is the one doing the login?
EDIT I'm using Novell.Directory.Ldap.NETStandard
EDIT The 'user' specified in the error above, is actually NOT a user at all. It is the AD registered name of the computer running IIS... If that makes any difference at all.
UPDATE After consulting with colleagues, I set up a new application pool on IIS, and tried to run the application as a specified user instead of the default passthrough. Exactly the same error message regardless of which user I set.

Try going via Network credentials that allows you to specify domain:
var networkCredential = new NetworkCredential(userName, password, domain);
conn.Bind(networkCredential);
If that does not work, specify auth type basic (not sure that the default is) before the call to bind.
conn.AuthType = AuthType.Basic;

LDAP Path And Permissions To Query Local User Directory?

I am working on a web application, ASP.NET, C#. Users are required to log in using an account local to the machine the app is running on, which I'll call "cyclops" for this example. I want the app to be able to query the local directory of users and groups to determine what groups the user is in. The code looks something like this:
DirectoryEntry entry = new DirectoryEntry("WinNT://cyclops/Users", "SomeServiceAccount",
"SvcAcctP#$$word", AuthenticationTypes.Secure);
entry.RefreshCache();
// Etc.
My two problems are:
That's pretty clearly not the correct path to use, but my research
and experimentation hasn't found the right answer. This MSDN
article talks about local paths, but doesn't fill in the blanks.
Do I use "LDAP://cyclops/Users", "WinNT://localhost/Users",
"WinNT://cyclops/cn=Users"?
As you can see, I'm providing the
credentials of a local service account. That account needs
permission to access the local directory, but I have no idea where
to set those permissions. Is it a specific file somewhere? Does
the account need to be a member of a particular group?
My experimentation has produced many errors: "The group name could not be found.", "The provider does not support searching...", "The server is not operational.", "Unknown error (0x80005004)", etc.
Thank you for your time...
-JW

WinNT requires the following format
WinNT://<domain/server>/<object name>,<object class>
To get groups of a given user, use
using (DirectoryEntry user = new DirectoryEntry("WinNT://./UserAccount,user"))
{
foreach(object group in (IEnumerable)user.Invoke("Groups",null))
{
using(DirectoryEntry g = new DirectoryEntry(group))
{
Response.Write(g.Name);
}
}
}
where
UserAccount is a name of required user.
dot stands for current machine (you can replace it with cyclops or use Environment.MachineName)
user credentials ("SomeServiceAccount", "SvcAcctP#$$word") might be required, depends on setup
To get users in a particular group, use
using (DirectoryEntry entry = new DirectoryEntry("WinNT://./Users,group"))
{
foreach (object member in (IEnumerable)entry.Invoke("Members"))
{
using(DirectoryEntry m = new DirectoryEntry(member))
{
Response.Write(m.Name);
}
}
}
where
Users is a name of group

Auth as administrator

I've done an application that basically goes through all active users on a network via DirectoryEntry, where I'm able to get each computers Username (login id), this is done by DE.UserName (DirectoryEntry).
Alright, so far so good, now with my problem; whenever I try to fetch it's password it's throwing an exception saying I need to have admin rights in order to get the password of each connected pc.
I am not the owner of the network, so I'm wondering if there's any way to auth as an admin or change your group to Administrator, or in any way bypass this so I can access it's password?
Code:
DirectoryEntry computers = new DirectoryEntry("WinNT://JBVAS");//The domain
IEnumerator enumerator = computers.Children.GetEnumerator();
while(enumerator.MoveNext())
{
DirectoryEntry entry = enumerator.Current as DirectoryEntry;
Console.WriteLine("Username: {0}{1}Password: {2}",
entry.Username, Environment.NewLine, entry.Password);
}

You could use impersonation to make your code (temporary) run under a higher privileged user.
I wrote an easy-to-use impersonation class some years back, you can find it over at CodeProject.com.
An example could be:
using ( new Impersonator( "myUsername", "myDomainname", "myPassword" ) )
{
// code that executes under the new context
}
Put your Active Directory code that needs administrator permissions inside the using block.