可能最简单的方法是PInvoke LogonUser Win32 api。

http://www.pinvoke.net/default.aspx/advapi32/LogonUser.html

MSDN参考在这里…

http://msdn.microsoft.com/en-us/library/aa378184.aspx

绝对要使用登录类型

LOGON32_LOGON_NETWORK (3)

这只创建了一个轻量级的令牌-完美的认证检查。(其他类型可用于构建交互式会话等)

使用DirectoryServices非常简单的解决方案:

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;
}

需要NativeObject访问来检测坏的用户/密码

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;
}   

这里介绍的几个解决方案缺乏区分错误用户/密码和需要更改的密码的能力。这可以通过以下方式来实现:

using System;
using System.DirectoryServices.Protocols;
using System.Net;

namespace ProtocolTest
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                LdapConnection connection = new LdapConnection("ldap.fabrikam.com");
                NetworkCredential credential = new NetworkCredential("user", "password");
                connection.Credential = credential;
                connection.Bind();
                Console.WriteLine("logged in");
            }
            catch (LdapException lexc)
            {
                String error = lexc.ServerErrorMessage;
                Console.WriteLine(lexc);
            }
            catch (Exception exc)
            {
                Console.WriteLine(exc);
            }
        }
    }
}

如果用户密码错误，或者用户不存在，error将包含

“8009030C: LdapErr: DSID-0C0904DC，注释:AcceptSecurityContext错误，数据52e, v1db1”，

如果用户密码需要修改，则包含

"8009030C: LdapErr: DSID-0C0904DC，注释:AcceptSecurityContext错误，数据773,v1db1"

lexc。ServerErrorMessage数据值是Win32错误码的十六进制表示。这些是通过调用Win32 LogonUser API调用返回的相同错误代码。下面的列表总结了一些常见的十六进制和十进制值:

525​ user not found ​(1317)
52e​ invalid credentials ​(1326)
530​ not permitted to logon at this time​ (1328)
531​ not permitted to logon at this workstation​ (1329)
532​ password expired ​(1330)
533​ account disabled ​(1331) 
701​ account expired ​(1793)
773​ user must reset password (1907)
775​ user account locked (1909)

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!)

我们在内部网做这些

你必须使用System.DirectoryServices;

下面是代码的核心部分

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();
        }
    }
}