Authenticating user with LDAP from PHP with only SamAccountName and Password?

Question

how can I authenticate from PHP using LDAP when I only have the SamAccountName and Password? Is there a way to bind with just SamAccountName and Password and without Distinguished Name. The only examples I have found assume you have the DN:

$server="XXX.XXX.XXX.XXX";
$dn = "cn=$username, "; 
$basedn="ou=users, ou=accounts, dc=domain, dc=com";

if (!($connect = ldap_connect($server))) { 
   die ("Could not connect to LDAP server"); 
} 

if (!($bind = ldap_bind($connect, "$dn" . "$basedn", $password))) {        
   die ("Could not bind to $dn"); 
} 

$sr = ldap_search($connect, $basedn,"$filter"); 
$info = ldap_get_entries($connect, $sr); 
$fullname=$info[0]["displayname"][0]; 
$fqdn=$info[0]["dn"]; 

Answer 1

This works for me. I spent many a days trying to figure this one out.

<?php

//We just need six varaiables here
$baseDN = 'CN=Users,DC=domain,DC=local';
$adminDN = "YourAdminDN";//this is the admin distinguishedName
$adminPswd = "YourAdminPass";
$username = 'Username';//this is the user samaccountname
$userpass = 'UserPass';
$ldap_conn = ldap_connect('ldaps://yourADdomain.local');//I'm using LDAPS here

if (! $ldap_conn) {
        echo ("<p style='color: red;'>Couldn't connect to LDAP service</p>");
    }
else {    
        echo ("<p style='color: green;'>Connection to LDAP service successful!</p>");
     }
//The first step is to bind the administrator so that we can search user info
$ldapBindAdmin = ldap_bind($ldap_conn, $adminDN, $adminPswd);

if ($ldapBindAdmin){
    echo ("<p style='color: green;'>Admin binding and authentication successful!!!</p>");

    $filter = '(sAMAccountName='.$username.')';
    $attributes = array("name", "telephonenumber", "mail", "samaccountname");
    $result = ldap_search($ldap_conn, $baseDN, $filter, $attributes);

    $entries = ldap_get_entries($ldap_conn, $result);  
    $userDN = $entries[0]["name"][0];  
    echo ('<p style="color:green;">I have the user DN: '.$userDN.'</p>');

    //Okay, we're in! But now we need bind the user now that we have the user's DN
    $ldapBindUser = ldap_bind($ldap_conn, $userDN, $userpass);

    if($ldapBindUser){
        echo ("<p style='color: green;'>User binding and authentication successful!!!</p>");        

        ldap_unbind($ldap_conn); // Clean up after ourselves.

    } else {
        echo ("<p style='color: red;'>There was a problem binding the user to LDAP :(</p>");   
    }     

} else {
    echo ("<p style='color: red;'>There was a problem binding the admin to LDAP :(</p>");   
} 
?>