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();
        }
    }
}

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

不幸的是，没有“简单”的方法来检查AD上的用户凭据。

使用到目前为止所介绍的每一种方法，你可能会得到一个假阴性:用户的信用将是有效的，但AD在某些情况下将返回false:

用户需要在下次登录时更改密码。 用户密码已过期。

ActiveDirectory不允许您使用LDAP来确定密码是否由于用户必须更改密码或密码是否过期而无效。

要确定密码更改或密码过期，您可以调用Win32:LogonUser()，并检查以下2个常量的windows错误码:

Error_password_must_change = 1907 Error_password_expired = 1330

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 = "";

        }
    }

我使用这个过程作为DLL登录到我们开发的其他应用程序… (我们目前正在使用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;
}

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!)