User & Password against Active Directory in C#

Get current login user from Active Directory in C#:

You can use the WindowsIdentity class to get the current Windows identity, and then the DirectoryEntry class to query Active Directory for information about the user. Here is an example:

WindowsIdentity currentIdentity = WindowsIdentity.GetCurrent();
DirectoryEntry directoryEntry = new DirectoryEntry("LDAP://" + currentIdentity.Name);
string currentUser = directoryEntry.Properties["sAMAccountName"].Value.ToString();
Console.WriteLine("Current user: " + currentUser);

Get the groups of a user in Active Directory in C#:

You can use the DirectorySearcher class to search for the user in Active Directory, and then the DirectoryEntry class to retrieve the groups that the user is a member of. Here is an example:

string userName = "jdoe";
DirectorySearcher searcher = new DirectorySearcher("(samaccountname=" + userName + ")");
SearchResult result = searcher.FindOne();
if (result != null)
{
    DirectoryEntry directoryEntry = result.GetDirectoryEntry();
    PropertyValueCollection groups = directoryEntry.Properties["memberOf"];
    foreach (string group in groups)
    {
        Console.WriteLine(group);
    }
}

Validate a username and password from Active Directory in C#:

You can use the DirectoryEntry class to bind to Active Directory with the username and password, and check if the binding was successful. Here is an example:

string userName = "jdoe";
string password = "password123";
DirectoryEntry directoryEntry = new DirectoryEntry("LDAP://mydomain.com", userName, password);
try
{
    object obj = directoryEntry.NativeObject;
    Console.WriteLine("Username and password are valid.");
}
catch (DirectoryServicesCOMException)
{
    Console.WriteLine("Username and password are invalid.");
}

Note that the NativeObject property is used to force a validation of the credentials. If the username and password are invalid, this will throw a DirectoryServicesCOMException.

C# Active Directory Authentication Example:

Active Directory (AD) authentication in C# involves connecting to an AD server and verifying user credentials.

using System.DirectoryServices.AccountManagement;

class Program {
    static void Main() {
        using (PrincipalContext context = new PrincipalContext(ContextType.Domain, "yourdomain.com")) {
            bool isValid = context.ValidateCredentials("username", "password");
            Console.WriteLine($"Is Valid: {isValid}");
        }
    }
}

Authenticate User Against Active Directory in C#:

Validate a user's credentials against Active Directory.

using System.DirectoryServices.AccountManagement;

bool AuthenticateUser(string username, string password) {
    using (PrincipalContext context = new PrincipalContext(ContextType.Domain, "yourdomain.com")) {
        return context.ValidateCredentials(username, password);
    }
}

Validate Active Directory Credentials in C#:

Check if provided credentials are valid in Active Directory.

bool isValid = AuthenticateUser("username", "password");
Console.WriteLine($"Credentials are valid: {isValid}");

C# Check Username and Password Against AD:

A simple function to check if a username and password are valid.

bool isValid = AuthenticateUser("username", "password");
Console.WriteLine($"Credentials are valid: {isValid}");

LDAP Authentication in C#:

Use the Lightweight Directory Access Protocol (LDAP) for authentication.

using System.DirectoryServices;

bool AuthenticateLDAP(string username, string password) {
    DirectoryEntry entry = new DirectoryEntry("LDAP://yourdomain.com", username, password);
    try {
        // Attempt to bind with the provided credentials
        object nativeObject = entry.NativeObject;
        return true;
    } catch (DirectoryServicesCOMException) {
        return false;
    }
}

Windows Authentication in C# Against Active Directory:

Leverage Windows authentication for seamless AD integration.

using System.Web.Security;

bool isWindowsAuthenticated = HttpContext.Current.Request.LogonUserIdentity.IsAuthenticated;

C# Login Form Using Active Directory:

Create a login form that authenticates users against Active Directory.

string username = "userInput";
string password = "passwordInput";

bool isValid = AuthenticateUser(username, password);
Console.WriteLine($"Login successful: {isValid}");

C# Active Directory Login Code Example:

A complete example of a login function using Active Directory.

bool loginSuccess = AuthenticateUser("username", "password");
Console.WriteLine($"Login success: {loginSuccess}");

LDAP Bind in C# for User Authentication:

Perform an LDAP bind operation for user authentication.

using System.DirectoryServices.Protocols;

bool AuthenticateLDAPBind(string username, string password) {
    using (LdapConnection connection = new LdapConnection("yourldapserver")) {
        connection.Bind(new NetworkCredential(username, password));
        return true; // If bind succeeds
    }
}

C# Check If User Exists in Active Directory:

Verify if a user exists in Active Directory.

bool userExists = CheckUserExists("username");
Console.WriteLine($"User exists: {userExists}");