LDAP and PHP connection failure

Question

I am trying to connect to a secure LDAP server (using LDAPs) via PHP, but I am having problems with it. I get the following error

Warning: ldap_bind() [function.ldap-bind]: Unable to bind to server: Can't contact LDAP server in /var/www/test.php on line 16

I works when I try to connect without LDAPs, but it is required that I use LDAPs because I am going to be dealing with sensitive information.

I am using the following code

<?php
// basic sequence with LDAP is connect, bind, search, interpret search
// result, close connection

echo "<h3>LDAP query test</h3>";
echo "Connecting ...";
$ds=ldap_connect("ldaps://server");  // must be a valid LDAP server!




print $ds;

if ($ds) { 
    echo "<br><br>Binding ..."; 
    $r=ldap_bind($ds);     // this is an "anonymous" bind, typically
                           // read-only access
    echo "Bind result is " . $r . "<br />";

    echo "Searching for (sn=S*) ...";
    // Search surname entry
    $sr=ldap_search($ds, "ou=people,o=server.ca,o=server", "uid=username*");  
    echo "Search result is " . $sr . "<br />";

    echo "Number of entires returned is " . ldap_count_entries($ds, $sr) . "<br />";

    echo "Getting entries ...<p>";
    $info = ldap_get_entries($ds, $sr);
    echo "Data for " . $info["count"] . " items returned:<p>";

print_r($info);
//    for ($i=0; $i<$info["count"]; $i++) {
//        echo "dn is: " . $info[$i]["dn"] . "<br />";
//        echo "first cn entry is: " . $info[$i]["cn"][0] . "<br />";
//        echo "first email entry is: " . $info[$i]["mail"][0] . "<br /><hr />";
//    }

    echo "Closing connection";
    ldap_close($ds);

} else {
    echo "<h4>Unable to connect to LDAP server</h4>";
}
?>

Answer 1

The problem is not related to the actual binding process (invalid credentials) as the warning would be a different one if the LDAP server could not authenticate your credentials. But as Paul Dixon noted the use of ldap_set_option($ds, LDAP_OPT_PROTOCOL_VERSION, 3) should be required - even though I don't think that this is the cause of your problems.

• Which LDAP server type are you connecting to? OpenLDAP, Active Directory or something else?
• What's the operating system of the computer running your PHP program?
• Are you using a self-signed SSL certificate on the LDAP server and is the certificate authority for the given certificate trusted by the machine running your PHP program?
• Which port does the LDAP server run on? 636 would be the "official" port for LDAPS. Perhaps you can add the port explicitly to the server address: ldaps://<<server>>:636.

ext/ldap has some issues with SSL/TLS secured connections. You can try to add

TLS_REQCERT never

to the ldap.conf (/etc/ldap.conf or /etc/ldap/ldap.conf on *nix-based systems) or for Windows machines create a ldap.conf with the above content in C:\OpenLDAP\sysconf\ldap.conf (the path must be an exact match as it's hard-coded into the extension).