这里是我完整的认证解决方案，供您参考。

首先，添加以下四个引用

 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 = "";

        }
    }

如果你被。net 2.0和托管代码困住了，这里有另一种处理本地和域帐户的方法:

using System;
using System.Collections.Generic;
using System.Text;
using System.Security;
using System.Diagnostics;

static public bool Validate(string domain, string username, string password)
{
    try
    {
        Process proc = new Process();
        proc.StartInfo = new ProcessStartInfo()
        {
            FileName = "no_matter.xyz",
            CreateNoWindow = true,
            WindowStyle = ProcessWindowStyle.Hidden,
            WorkingDirectory = Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData),
            UseShellExecute = false,
            RedirectStandardError = true,
            RedirectStandardOutput = true,
            RedirectStandardInput = true,
            LoadUserProfile = true,
            Domain = String.IsNullOrEmpty(domain) ? "" : domain,
            UserName = username,
            Password = Credentials.ToSecureString(password)
        };
        proc.Start();
        proc.WaitForExit();
    }
    catch (System.ComponentModel.Win32Exception ex)
    {
        switch (ex.NativeErrorCode)
        {
            case 1326: return false;
            case 2: return true;
            default: throw ex;
        }
    }
    catch (Exception ex)
    {
        throw ex;
    }

    return false;
}   

试试这段代码 (注意:报告不能在windows server 2000上工作)

#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

除非你需要为“LogonException”创建自己的自定义异常

完整的. net解决方案是使用来自系统的类。DirectoryServices名称空间。它们允许直接查询AD服务器。下面是一个可以做到这一点的小样本:

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

这段代码使用提供的凭据直接连接到AD服务器。如果凭证无效，则search . findone()将抛出异常。ErrorCode是一个对应于“无效的用户名/密码”COM错误。

您不需要以AD用户的身份运行代码。事实上，我成功地使用它在AD服务器上查询信息，从域外的客户端!

另一个.NET调用用于快速验证LDAP凭据:

using System.DirectoryServices;

using(var DE = new DirectoryEntry(path, username, password)
{
    try
    {
        DE.RefreshCache(); // This will force credentials validation
    }
    catch (COMException ex)
    {
        // Validation failed - handle how you want
    }
}

如果你使用的是。net 3.5或更新版本，你可以使用System.DirectoryServices.AccountManagement命名空间轻松验证你的凭证:

// 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");
}

它简单，可靠，在你的端是100%的c#托管代码——你还能要求什么呢?: -)

在这里阅读所有内容:

在.NET Framework 3.5中管理目录安全主体 System.DirectoryServices.AccountManagement上的MSDN文档

更新:

正如在另一个SO问题(及其答案)中概述的那样，对于用户的旧密码，这个调用可能会返回True。只是要注意这种行为，如果发生这种情况不要太惊讶:-)(感谢@MikeGledhill指出这一点!)