(PHP Extension) FTP Connect, Examine Server Certificate, and then Authenticate

Demonstrates how to connect to an FTP server, examine the server's SSL/TLS certificate, and then, if it meets the application's security requirements, proceed to authenticate.

Chilkat PHP Downloads PHP Extension for Windows, Linux, MAC OS X, Alpine Linux, Solaris, OpenBSD, FreeBSD, and Linux armhf/aarch64

<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

//  This example assumes Chilkat Ftp2 to have been previously unlocked.
//  See Unlock Ftp2 for sample code.

$ftp = new CkFtp2();

$ftp->put_Hostname('www.authtls-ftps-server.com');
$ftp->put_Username('FTP_LOGIN');
$ftp->put_Password('FTP_PASSWORD');
$ftp->put_AuthTls(true);
$ftp->put_Port(21);

//  Connect to the FTP server using explicit TLS (AUTH TLS).
$success = $ftp->ConnectOnly();
if ($success != true) {
    print $ftp->lastErrorText() . "\n";
    exit;
}

//  Get the FTP server's certificate.
// serverCert is a CkCert
$serverCert = $ftp->GetSslServerCert();
if ($ftp->get_LastMethodSuccess() != true) {
    print $ftp->lastErrorText() . "\n";
    exit;
}

//  Now that we have the certificate, we can check it in any way we desire.
//  (See the online reference documentation for the certificate object's methods
//  and properties)...

//  Assuming the certificate is OK, proceed to authenticate with the FTP server.
$success = $ftp->LoginAfterConnectOnly();
if ($success != true) {
    print $ftp->lastErrorText() . "\n";
    exit;
}

// 
//  Proceed with uploading/download files, etc...
// 

$ftp->Disconnect();
print 'Success.' . "\n";

?>