I want to know if there's a way to validate domain credential and make sure we don't use the Cached Domain Credential ?
I use this to validate the credential :
bool valid = false;
using (PrincipalContext context = new PrincipalContext(ContextType.Domain))
{
valid = context.ValidateCredentials( username, password );
}
The problem is when I change the password, the old password is still working.
EDIT : If you force the password to be reset, the cached domain credential will not be use. But between the moment we force the reset, and moment the user reset the password, the old password will still work.
Question already has an answer Why does Active Directory validate last password?
Solution is to use a Kerberos authentication.
The following code shows how you can perform credential validation using only Kerberos. The authentication method at use will not fall back to NTLM in the event of failure.
private const int ERROR_LOGON_FAILURE = 0x31;
private bool ValidateCredentials(string username, string password, string domain)
{
NetworkCredential credentials
= new NetworkCredential(username, password, domain);
LdapDirectoryIdentifier id = new LdapDirectoryIdentifier(domain);
using(LdapConnection connection = new LdapConnection(id, credentials, AuthType.Kerberos))
{
connection.SessionOptions.Sealing = true;
connection.SessionOptions.Signing = true;
try
{
connection.Bind();
}
catch (LdapException lEx)
{
if (ERROR_LOGON_FAILURE == lEx.ErrorCode)
{
return false;
}
throw;
}
return true;
}
you might try something like this
try
{
using (var directoryEntry = new DirectoryEntry(ldapPath, userName, password))
{
var invocation = directoryEntry.NativeObject;
return true;
}
}
catch (Exception ex)
{
return false;
}
Related
What I have is a function that allows a domain user to be authenticated against their LDAP credentials. However, it works long as I hard-code a known password as a raw string... which is a no-no, of course. I wish to pass in a string value received from a TextBox I have set up. Here is the function:
public static bool fnValLDAPCreds()
{
bool validation;
try
{
LdapConnection ADConn = new LdapConnection(new LdapDirectoryIdentifier((string)null, false, false));
NetworkCredential NetCred = new NetworkCredential(Environment.UserName, "Password123", Environment.UserDomainName);
ADConn.Credential = NetCred;
ADConn.AuthType = AuthType.Negotiate;
// the user's authenticated here; creds used to login on the domain controller.
ADConn.Bind(NetCred);
validation = true;
MessageBox.Show("You were successfully authenticated against AD using LDAP!");
}
catch (LdapException)
{
validation = false;
MessageBox.Show("Your login was unsuccesful. Try a different set of credentials.");
}
return validation;
}
What I've tried to do was substitute in a value from my TextBox, but since it lies in the static bool I have not been successful with making any external references to a control in the current context. I'm calling this function in button handler to fire it off. How can I swap in a string DomPassWord variable that gets its value from the textbox I have setup to obtain it?
NetworkCredential NetCred = new NetworkCredential(Environment.UserName, DomPassWord, Environment.UserDomainName); is what I'm striving for, as I can securely match a password in the domain with no hard-coding, using something like DomPassWord = txtUserPW.Text. Tried the SecureString route, but was unsuccessful in that regard as well. Any ideas?
You cannot access text boxes inside a static method, since they aren't static fields (at least it looks like it from what you've written).
But you can simply pass your arguments to your method. Change it to something like this:
public void ButtonClick(object sender, EventArgs args)
{
// bool valid = fnValLDAPCreds(Environment.UserName, "Password123", Environment.UserDomainName);
bool valid = fnValLDAPCreds(txtUserName.Text, txtUserPW.Text, Environment.UserDomainName);
}
public static bool fnValLDAPCreds(string username, string password, string domain)
{
try
{
LdapConnection ADConn = new LdapConnection(new LdapDirectoryIdentifier((string)null, false, false));
NetworkCredential NetCred = new NetworkCredential(username, password, domain);
ADConn.Credential = NetCred;
ADConn.AuthType = AuthType.Negotiate;
// the user's authenticated here; creds used to login on the domain controller.
ADConn.Bind(NetCred);
MessageBox.Show("You were successfully authenticated against AD using LDAP!");
return true;
}
catch (LdapException)
{
MessageBox.Show("Your login was unsuccesful. Try a different set of credentials.");
return false;
}
}
Kinda tangential, but have you thought about AuthType.Ntlm? If all you're doing this for is to make sure user 'Charlie' is actually Charlie by making him type in his password? Then you're on the right track. But if you're trying to connect in to AD using the current user credentials as a way of getting to AD itself? Then you might want to take a look at
ADConn.AuthType = AuthType.Ntlm;
... and letting windows handle this for you (no need to have the user type in a password at all - it'll use their current windows credentials.)
I have the following two implementations of authenticating users with LDAP and LDAPS and I was wondering which was better / more correct. For the record, both of these work on both SSL and non-SSL connections.
I'm also curious because when watching with Wireshark on the Non-SSL PrincipalContext version, I still see traffic on Port 636. Of the four combinations (Non-SSL LdapConnection, SSL LdapConnection, Non-SSL PrincipalContext, SSL PrincipalContext) it is the only one that has traffic on both Port 389 and 636 instead of just one or the other. What could be causing this?
LDAP Connection Method:
bool userAuthenticated = false;
var domainName = DomainName;
if (useSSL)
{
domainName = domainName + ":636";
}
try
{
using (var ldap = new LdapConnection(domainName))
{
var networkCredential = new NetworkCredential(username, password, domainName);
ldap.SessionOptions.VerifyServerCertificate = new VerifyServerCertificateCallback((con, cer) => true);
ldap.SessionOptions.SecureSocketLayer = useSSL;
ldap.SessionOptions.ProtocolVersion = 3;
ldap.AuthType = AuthType.Negotiate;
ldap.Bind(networkCredential);
}
// If the bind succeeds, we have a valid user/pass.
userAuthenticated = true;
}
catch (LdapException ldapEx)
{
// Error Code 0x31 signifies invalid credentials, anything else will be caught outside.
if (!ldapEx.ErrorCode.Equals(0x31))
{
throw;
}
}
return userAuthenticated;
PrincipalContext Method:
bool userAuthenticated = false;
var domainName = DomainName;
if (useSSL)
{
domainName = domainName + ":636";
ContextOptions options = ContextOptions.SimpleBind | ContextOptions.SecureSocketLayer;
using (PrincipalContext pc = new PrincipalContext(ContextType.Domain, domainName, null, options))
{
userAuthenticated = pc.ValidateCredentials(username, password, options);
}
}
else
{
using (PrincipalContext pc = new PrincipalContext(ContextType.Domain, domainName))
{
userAuthenticated = pc.ValidateCredentials(username, password);
}
}
return userAuthenticated;
#DTI-Matt, in the examples above, you use VerifyServerCertificate callback that always returns true. This, essentially, defies the purpose of connecting to LDAP over SSL, as no real certificate check is performed.
While you could implement a real certificate check using X509Chain and/or X509Certificate2 classes, it seems PrincipalContext handles the checks for you.
To summarize, both LdapConnection and PrincipalContext provide very similar functionality, in means of connecting to an LDAP server over plain or SSL connection. You have to supply LdapConnection much more hand-written code for it to work properly. On the other hand, PrincipalContext gives you the same functionality with less code to write by hand.
As a note, connections to port 636 (your default LDAP over SSL port), by non-SSL PrincipalContext may be explained by the fact this class tries to connect as secure as possible.
This is what we ended up with that is working over SSL/Non-SSL.
public bool UserValid(string username, string password, bool useSSL)
{
bool userAuthenticated = false;
var domainName = DomainName;
if (useSSL)
{
domainName = domainName + ":636";
}
try
{
using (var ldap = new LdapConnection(domainName))
{
var networkCredential = new NetworkCredential(username, password, DomainName); // Uses DomainName without the ":636" at all times, SSL or not.
ldap.SessionOptions.VerifyServerCertificate += VerifyServerCertificate;
ldap.SessionOptions.SecureSocketLayer = useSSL;
ldap.AuthType = AuthType.Negotiate;
ldap.Bind(networkCredential);
}
// If the bind succeeds, we have a valid user/pass.
userAuthenticated = true;
}
catch (LdapException ldapEx)
{
// Error Code 0x31 signifies invalid credentials, so return userAuthenticated as false.
if (!ldapEx.ErrorCode.Equals(0x31))
{
throw;
}
}
return userAuthenticated;
}
private bool VerifyServerCertificate(LdapConnection connection, X509Certificate certificate)
{
X509Certificate2 cert = new X509Certificate2(certificate);
if (!cert.Verify())
{
// Could not validate potentially self-signed SSL certificate. Prompting user to install certificate themselves.
X509Certificate2UI.DisplayCertificate(cert);
// Try verifying again as the user may have allowed the certificate, and return the result.
if (!cert.Verify())
{
throw new SecurityException("Could not verify server certificate. Make sure this certificate comes from a trusted Certificate Authority.");
}
}
return true;
}
I want to create an Application for editing user accounts on a Server.
The Server do not use AD only local accounts.
I use the following code to connect the remote server:
try
{
PrincipalContext oPrincipalContext = new PrincipalContext(ContextType.Machine, "192.168.123.110", null, ContextOptions.Negotiate, "Administrator", "password");
try
{
MessageBox.Show(oPrincipalContext.ConnectedServer);
GroupPrincipal oGroupPrincipal = GroupPrincipal.FindByIdentity(oPrincipalContext, "Goetter");
try
{
// perform operations here
}
finally
{
oGroupPrincipal.Dispose();
}
}
finally
{
oPrincipalContext.Dispose();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
Whenever I try this, I get an exception, that the user and or password is not authorized, independent of the user I use. Administrator is the build in Admin user account.
Does PrincipalContext only works with AD or also with local accounts? Is anything wrong with my code?
using(PrincipalContext oPrincipalContext = new PrincipalContext(ContextType.Machine, computer.Name, null, ContextOptions.Negotiate, Settings.UserName, Settings.UserPassword))
using(GroupPrincipal oGroupPrincipal = GroupPrincipal.FindByIdentity(oPrincipalContext, Settings.AdministratorsGroup))
{
// perform operations here
}
Change your code and wrap it around a using statement otherwise you may have some errors when trying to call the Dispose() method reason being when you try to dispose the connection may have already been closed by then.
you can use this code here and try either of the examples if you are using ActiveDirectory
example 1
If you work on .NET 3.5, 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");
}
Example 2
using System.Security;
using System.DirectoryServices.AccountManagement;
public struct Credentials
{
public string Username;
public string Password;
}
public class Domain_Authentication
{
public Credentials Credentials;
public string Domain;
public Domain_Authentication(string Username, string Password, string SDomain)
{
Credentials.Username = Username;
Credentials.Password = Password;
Domain = SDomain;
}
public bool IsValid()
{
using (PrincipalContext pc = new PrincipalContext(ContextType.Domain, Domain))
{
// validate the credentials
return pc.ValidateCredentials(Credentials.Username, Credentials.Password);
}
}
}
The public bool IsValid() Method above should work for what you are looking for.
Have a look at PrincipalContext.ValidateCredentials
for your FindByIdentity portion you can try the following replacement code
string strName = System.Security.Principal.WindowsIdentity.GetCurrent().Name;
// This is here because of a .Net error that gets 0x80005000 on "isUser = user.IsMemberOf(groupU);"
string domainName = strName.Split('\\')[0];
var pc = new PrincipalContext(ContextType.Domain, domainName);
Additional Reference Link StackOverFlow Post
ContextType.Machine
i need to verify if the password is correct for a user.
i have this code:
private bool checkOldPasswordValid(string password, string username)
{
using (DirectoryEntry entry = new DirectoryEntry("WinNT://" + Environment.MachineName + ",computer"))
{
entry.Username = username;
entry.Password = password;
DirectorySearcher searcher = new DirectorySearcher(entry);
searcher.Filter = "(objectclass=user)";
try
{
searcher.FindOne();
}
catch (Exception ex)
{
return false;
}
return true;
}
}
but then directory searcher is not supported with WinNt, so i found another way to loop through all records.
foreach (DirectoryEntry dc in entry.Children)
{
// prints the name
System.Diagnostics.Debug.WriteLine(dc.Name);
}
but this just gets the name and doesnt verify the password.
please help . thanks
To autenticate against LDAP or WinNT, you need no DirectorySearcher. You only need to get the NativeObject from your DirectoryEntry instance. Here's a code sample that might guide you through the way.
public bool Authenticate(string username, string password, string domain) {
bool authenticated = false;
using (DirectoryEntry entry = new DirectoryEntry(#"WinNT://" + domain, username, password) {
try {
object nativeObject = entry.NativeObject;
authenticated = true;
} catch (DirectoryServicesCOMException ex) {
}
}
return authenticated;
}
This code will return either a user is authentic or not. Once you can get the NativeObject property using this DirectoryEntry class instance, this means that the AD (or local computer) used impersonation to get this object. If you get the object without having a thrown exception, this means that the AD (or local computer) was able to authenticate the impersonnated user.
While you can use the currently authenticated user by specifying no username and password, but only the domain (or local computer), by specifying a username and password, you say you want to use impersonnation, so the security infrastructure will use the given username and password to try to retrieve the NativeObject property from this DirectoryEntry class instance.
To authenticate against the AD, just replace the "WinNT://" for "LDAP://".
You can use DirectoryEntry itself.
See the example here: http://support.microsoft.com/kb/316748
Why are you using WinNT:// anyways?
Why does the following code lock the account out after one unsuccessful attempt when the policy in AD is set to three attempts? Is there a better way of checking credentials programmatically against AD.
private bool Authenticate(string userName,
string password, string domain)
{
bool authentic = false;
try
{
DirectoryEntry entry = new DirectoryEntry("LDAP://" + domain,
userName, password);
object nativeObject = entry.NativeObject;
authentic = true;
}
catch (DirectoryServicesCOMException) { }
return authentic;
}
Working fine when the correct credentials are entered...
Thanks,
You might find what you need in this article:
http://www.codeproject.com/Articles/90142/Everything-in-Active-Directory-via-Csharp-NET-3-5-.aspx
specifically the ValidateCredentials method.