PHP - Swiftmailer using STARTTLS and self signed certificates

Question

I'm trying to send an email with php and swiftmailer, using STARTTLS, but I'm getting a certificate error. I have root access to the SMTP server, and the certificate used is self-signed. I'm using Debian on both machines (web server and smtp server)

PHP message: PHP Warning: stream_socket_enable_crypto(): SSL operation failed with code 1. OpenSSL Error messages: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed in [..]/lib/classes/Swift/Transport/StreamBuffer.php on line 97 PHP message: PHP Fatal error: Uncaught exception 'Swift_TransportException' with message 'Unable to connect with TLS encryption' in [..]/lib/classes/Swift/Transport/EsmtpTransport.php:294

Do I need to add my own certificate somewhere to get it accepted? Or is this some OpenSSL configuration error?

Answer 1

Editor's note: disabling SSL verification has security implications. Without verification of the authenticity of SSL/HTTPS connections, a malicious attacker can impersonate a trusted endpoint (such as GitHub or some other remote Git host), and you'll be vulnerable to a Man-in-the-Middle Attack.

Be sure you fully understand the security issues before using this as a solution.

Swiftmailer has now been updated to include an option for this. It can now be solved using the setStreamOptions method from your Swift_SmtpTransport instance rather than editing the swift class.

$transport = Swift_SmtpTransport::newInstance('smtp.server.com', 123, 'tls')
    ->setUsername('username')
    ->setPassword('password')
    ->setStreamOptions(array('ssl' => array('allow_self_signed' => true, 'verify_peer' => false)));

Answer 2

Editor's note: disabling SSL verification has security implications. Without verification of the authenticity of SSL/HTTPS connections, a malicious attacker can impersonate a trusted endpoint (such as GitHub or some other remote Git host), and you'll be vulnerable to a Man-in-the-Middle Attack.

Be sure you fully understand the security issues before using this as a solution.

You do not need to edit /vendor files. You can specify (undocumented) options in your config/mail.php file:

'stream' => [
    'ssl' => [
        'allow_self_signed' => true,
        'verify_peer' => false,
        'verify_peer_name' => false,
    ],
],

You can check it yourself in vendor/laravel/framework/src/Illuminate/Mail/TransportManager.php on line ~50:

...
if (isset($config['stream'])) {
    $transport->setStreamOptions($config['stream']);
}
...

Needless to say, circumventing peer verification has huge security implications (read vulnerabilities). I imagine this solution for some dev or local environment, never in production or even in an Internet/Publicly available app.

Answer 3

I got the same problem using Swiftmailer in Laravel.

Looks like there is no option for this in Swiftmailer. Clean solution would be to add your own root CA to your server and sign your mail server certificate with this CA. The certificate would be valid after this. See for example this tutorial.

Editor's note: disabling SSL verification has security implications. Without verification of the authenticity of SSL/HTTPS connections, a malicious attacker can impersonate a trusted endpoint (such as GitHub or some other remote Git host), and you'll be vulnerable to a Man-in-the-Middle Attack.

Be sure you fully understand the security issues before using this as a solution.

Anyway, a quick dirty hack you should not use would be to edit swiftmailer\swiftmailer\lib\classes\Swift\Transport\StreamBuffer.php. In _establishSocketConnection() line 253 replace:

$options = array();

with something like this:

$options = array('ssl' => array('allow_self_signed' => true, 'verify_peer' => false));

This will change the ssl options of stream_context_create() (a few lines below $options):

$this->_stream = @stream_socket_client($host.':'.$this->_params['port'], $errno, 
    $errstr, $timeout, STREAM_CLIENT_CONNECT, stream_context_create($options));

Answer 4

Editor's note: disabling SSL verification has security implications. Without verification of the authenticity of SSL/HTTPS connections, a malicious attacker can impersonate a trusted endpoint (such as GitHub or some other remote Git host), and you'll be vulnerable to a Man-in-the-Middle Attack.

Be sure you fully understand the security issues before using this as a solution.

For me, I had to add $transport->setStreamOptions(array('ssl' => array('allow_self_signed' => true, 'verify_peer' => false, 'verify_peer_name' => false))); to the Mailer.php file, see:

    /**
     * Returns the SMTP transport
     *
     * @return \Swift_SmtpTransport
     */
    protected function getSmtpInstance(): \Swift_SmtpTransport {
            $transport = new \Swift_SmtpTransport();
            $transport->setTimeout($this->config->getSystemValue('mail_smtptimeout', 10));
            $transport->setHost($this->config->getSystemValue('mail_smtphost', '127.0.0.1'));
            $transport->setPort($this->config->getSystemValue('mail_smtpport', 25));
            if ($this->config->getSystemValue('mail_smtpauth', false)) {
                    $transport->setUsername($this->config->getSystemValue('mail_smtpname', ''));
                    $transport->setPassword($this->config->getSystemValue('mail_smtppassword', ''));
                    $transport->setAuthMode($this->config->getSystemValue('mail_smtpauthtype', 'LOGIN'));
            }
            $smtpSecurity = $this->config->getSystemValue('mail_smtpsecure', '');
            if (!empty($smtpSecurity)) {
                    $transport->setEncryption($smtpSecurity);
            }
            $streamingOptions = $this->config->getSystemValue('mail_smtpstreamoptions', []);
            if (is_array($streamingOptions) && !empty($streamingOptions)) {
                    $transport->setStreamOptions($streamingOptions);
            }

            /* EDIT - allow self-signed mail cert */
            $transport->setStreamOptions(array('ssl' => array('allow_self_signed' => true, 'verify_peer' => false, 'verify_peer_name' => false)));
            /* EDIT end */

            return $transport;
    }

I got this from another link, can't find it now.

One think that I did extra to the other answers was to specify the 'verify_peer_name' => false