How can I validate a username and password against Active Directory? I simply want to check if a username and password are correct.
15 Answers
If you work on .NET 3.5 or newer, you can use the System.DirectoryServices.AccountManagement namespace and easily verify your credentials:
// create a "principal context" - e.g. your domain (could be machine, too)
using(PrincipalContext pc = new PrincipalContext(ContextType.Domain, "YOURDOMAIN"))
{
// validate the credentials
bool isValid = pc.ValidateCredentials("myuser", "mypassword");
}
It's simple, it's reliable, it's 100% C# managed code on your end - what more can you ask for? :-)
Read all about it here:
- Managing Directory Security Principals in the .NET Framework 3.5
- MSDN docs on System.DirectoryServices.AccountManagement
Update:
As outlined in this other SO question (and its answers), there is an issue with this call possibly returning True for old passwords of a user. Just be aware of this behavior and don't be too surprised if this happens :-) (thanks to @MikeGledhill for pointing this out!)
We do this on our Intranet
You have to use System.DirectoryServices;
Here are the guts of the code
using (DirectoryEntry adsEntry = new DirectoryEntry(path, strAccountId, strPassword))
{
using (DirectorySearcher adsSearcher = new DirectorySearcher(adsEntry))
{
//adsSearcher.Filter = "(&(objectClass=user)(objectCategory=person))";
adsSearcher.Filter = "(sAMAccountName=" + strAccountId + ")";
try
{
SearchResult adsSearchResult = adsSearcher.FindOne();
bSucceeded = true;
strAuthenticatedBy = "Active Directory";
strError = "User has been authenticated by Active Directory.";
}
catch (Exception ex)
{
// Failed to authenticate. Most likely it is caused by unknown user
// id or bad strPassword.
strError = ex.Message;
}
finally
{
adsEntry.Close();
}
}
}
very simple solution using DirectoryServices:
using System.DirectoryServices;
//srvr = ldap server, e.g. LDAP://domain.com
//usr = user name
//pwd = user password
public bool IsAuthenticated(string srvr, string usr, string pwd)
{
bool authenticated = false;
try
{
DirectoryEntry entry = new DirectoryEntry(srvr, usr, pwd);
object nativeObject = entry.NativeObject;
authenticated = true;
}
catch (DirectoryServicesCOMException cex)
{
//not authenticated; reason why is in cex
}
catch (Exception ex)
{
//not authenticated due to some other exception [this is optional]
}
return authenticated;
}
the NativeObject access is required to detect a bad user/password
Unfortunately there is no "simple" way to check a users credentials on AD.
With every method presented so far, you may get a false-negative: A user's creds will be valid, however AD will return false under certain circumstances:
- User is required to Change Password at Next Logon.
- User's password has expired.
ActiveDirectory will not allow you to use LDAP to determine if a password is invalid due to the fact that a user must change password or if their password has expired.
To determine password change or password expired, you may call Win32:LogonUser(), and check the windows error code for the following 2 constants:
- ERROR_PASSWORD_MUST_CHANGE = 1907
- ERROR_PASSWORD_EXPIRED = 1330
Probably easiest way is to PInvoke LogonUser Win32 API.e.g.
MSDN Reference here...
Definitely want to use logon type
LOGON32_LOGON_NETWORK (3)
This creates a lightweight token only - perfect for AuthN checks. (other types can be used to build interactive sessions etc.)
A full .Net solution is to use the classes from the System.DirectoryServices namespace. They allow to query an AD server directly. Here is a small sample that would do this:
using (DirectoryEntry entry = new DirectoryEntry())
{
entry.Username = "here goes the username you want to validate";
entry.Password = "here goes the password";
DirectorySearcher searcher = new DirectorySearcher(entry);
searcher.Filter = "(objectclass=user)";
try
{
searcher.FindOne();
}
catch (COMException ex)
{
if (ex.ErrorCode == -2147023570)
{
// Login or password is incorrect
}
}
}
// FindOne() didn't throw, the credentials are correct
This code directly connects to the AD server, using the credentials provided. If the credentials are invalid, searcher.FindOne() will throw an exception. The ErrorCode is the one corresponding to the "invalid username/password" COM error.
You don't need to run the code as an AD user. In fact, I succesfully use it to query informations on an AD server, from a client outside the domain !
Try this code (NOTE: Reported to not work on windows server 2000)
#region NTLogonUser
#region Direct OS LogonUser Code
[DllImport( "advapi32.dll")]
private static extern bool LogonUser(String lpszUsername,
String lpszDomain, String lpszPassword, int dwLogonType,
int dwLogonProvider, out int phToken);
[DllImport("Kernel32.dll")]
private static extern int GetLastError();
public static bool LogOnXP(String sDomain, String sUser, String sPassword)
{
int token1, ret;
int attmpts = 0;
bool LoggedOn = false;
while (!LoggedOn && attmpts < 2)
{
LoggedOn= LogonUser(sUser, sDomain, sPassword, 3, 0, out token1);
if (LoggedOn) return (true);
else
{
switch (ret = GetLastError())
{
case (126): ;
if (attmpts++ > 2)
throw new LogonException(
"Specified module could not be found. error code: " +
ret.ToString());
break;
case (1314):
throw new LogonException(
"Specified module could not be found. error code: " +
ret.ToString());
case (1326):
// edited out based on comment
// throw new LogonException(
// "Unknown user name or bad password.");
return false;
default:
throw new LogonException(
"Unexpected Logon Failure. Contact Administrator");
}
}
}
return(false);
}
#endregion Direct Logon Code
#endregion NTLogonUser
except you'll need to create your own custom exception for "LogonException"
For me both of these below worked, make sure your Domain is given with LDAP:// in start
//"LDAP://" + domainName
private void btnValidate_Click(object sender, RoutedEventArgs e)
{
try
{
DirectoryEntry de = new DirectoryEntry(txtDomainName.Text, txtUsername.Text, txtPassword.Text);
DirectorySearcher dsearch = new DirectorySearcher(de);
SearchResult results = null;
results = dsearch.FindOne();
MessageBox.Show("Validation Success.");
}
catch (LdapException ex)
{
MessageBox.Show($"Validation Failure. {ex.GetBaseException().Message}");
}
catch (Exception ex)
{
MessageBox.Show($"Validation Failure. {ex.GetBaseException().Message}");
}
}
private void btnValidate2_Click(object sender, RoutedEventArgs e)
{
try
{
LdapConnection lcon = new LdapConnection(new LdapDirectoryIdentifier((string)null, false, false));
NetworkCredential nc = new NetworkCredential(txtUsername.Text,
txtPassword.Text, txtDomainName.Text);
lcon.Credential = nc;
lcon.AuthType = AuthType.Negotiate;
lcon.Bind(nc);
MessageBox.Show("Validation Success.");
}
catch (LdapException ex)
{
MessageBox.Show($"Validation Failure. {ex.GetBaseException().Message}");
}
catch (Exception ex)
{
MessageBox.Show($"Validation Failure. {ex.GetBaseException().Message}");
}
}
Here my complete authentication solution for your reference.
First, add the following four references
using System.DirectoryServices;
using System.DirectoryServices.Protocols;
using System.DirectoryServices.AccountManagement;
using System.Net;
private void AuthUser() {
try{
string Uid = "USER_NAME";
string Pass = "PASSWORD";
if (Uid == "")
{
MessageBox.Show("Username cannot be null");
}
else if (Pass == "")
{
MessageBox.Show("Password cannot be null");
}
else
{
LdapConnection connection = new LdapConnection("YOUR DOMAIN");
NetworkCredential credential = new NetworkCredential(Uid, Pass);
connection.Credential = credential;
connection.Bind();
// after authenticate Loading user details to data table
PrincipalContext ctx = new PrincipalContext(ContextType.Domain);
UserPrincipal user = UserPrincipal.FindByIdentity(ctx, Uid);
DirectoryEntry up_User = (DirectoryEntry)user.GetUnderlyingObject();
DirectorySearcher deSearch = new DirectorySearcher(up_User);
SearchResultCollection results = deSearch.FindAll();
ResultPropertyCollection rpc = results[0].Properties;
DataTable dt = new DataTable();
DataRow toInsert = dt.NewRow();
dt.Rows.InsertAt(toInsert, 0);
foreach (string rp in rpc.PropertyNames)
{
if (rpc[rp][0].ToString() != "System.Byte[]")
{
dt.Columns.Add(rp.ToString(), typeof(System.String));
foreach (DataRow row in dt.Rows)
{
row[rp.ToString()] = rpc[rp][0].ToString();
}
}
}
//You can load data to grid view and see for reference only
dataGridView1.DataSource = dt;
}
} //Error Handling part
catch (LdapException lexc)
{
String error = lexc.ServerErrorMessage;
string pp = error.Substring(76, 4);
string ppp = pp.Trim();
if ("52e" == ppp)
{
MessageBox.Show("Invalid Username or password, contact ADA Team");
}
if ("775" == ppp)
{
MessageBox.Show("User account locked, contact ADA Team");
}
if ("525" == ppp)
{
MessageBox.Show("User not found, contact ADA Team");
}
if ("530" == ppp)
{
MessageBox.Show("Not permitted to logon at this time, contact ADA Team");
}
if ("531" == ppp)
{
MessageBox.Show("Not permitted to logon at this workstation, contact ADA Team");
}
if ("532" == ppp)
{
MessageBox.Show("Password expired, contact ADA Team");
}
if ("533" == ppp)
{
MessageBox.Show("Account disabled, contact ADA Team");
}
if ("533" == ppp)
{
MessageBox.Show("Account disabled, contact ADA Team");
}
} //common error handling
catch (Exception exc)
{
MessageBox.Show("Invalid Username or password, contact ADA Team");
}
finally {
tbUID.Text = "";
tbPass.Text = "";
}
}
I'm using this procedure as a DLL to login in other app that we developed...
(We are currently using this with OpenEdge Progress)
public static string AzureLogin(string user, string password) {
string status;
try {
new DirectorySearcher(new DirectoryEntry("LDAP://yourdomain.com", user, password) {
AuthenticationType = AuthenticationTypes.Secure,
Username = user,
Password = password
}) {
Filter = "(objectclass=user)"
}.FindOne().Properties["displayname"][0].ToString();
status = $"SUCCESS - User {user} has logged in.";
} catch(System.Exception e) {
status = $"ERROR - While logging in: {e}";
}
return status;
}
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