Transport SSL

Transport — SSL

The ssl:// scheme variant of Transport TLS. Functionally identical class layout; the only difference is the URL scheme passed to stream_socket_server / stream_socket_client, which affects PHP's default cipher negotiation.

When to choose SSL over TLS

In nearly every situation — don't. Pick Transport::TLS.

The ssl:// scheme exists mostly for compatibility with legacy PHP code. Modern peers negotiate TLS 1.2 / 1.3 either way; the scheme just changes which cipher family PHP starts the negotiation in.

The one common case where Transport::SSL is the natural fit is implicit TLS services with a long-established convention of being called over ssl:// — e.g. SMTPS on port 465, IMAPS on 993, POP3S on 995. Either transport works there; SSL is what existing PHP examples in the wild use.

Server

use InitPHP\Socket\Socket;
use InitPHP\Socket\Enum\Transport;

$server = Socket::server(Transport::SSL, '0.0.0.0', 8443, timeout: 5.0)
    ->option('local_cert', __DIR__ . '/server.pem');

$server->listen();
$server->live(function ($srv, $conn) {
    $payload = $conn->read();
    if ($payload !== null) {
        $conn->write("ssl-echo: {$payload}");
    }
});

Every configuration knob, lifecycle method and exception type is identical to Transport TLS — read that page for the full reference.

Client

use InitPHP\Socket\Socket;
use InitPHP\Socket\Enum\Transport;

$client = Socket::client(Transport::SSL, 'smtp.gmail.com', 465, timeout: 10.0)
    ->option('verify_peer', false)
    ->option('verify_peer_name', false);

$client->connect();
$client->write("EHLO [127.0.0.1]\r\n");
echo $client->read(1024);
$client->disconnect();

Pinning a specific protocol version

If you have a server that only speaks a specific version, pin it via crypto():

use InitPHP\Socket\Enum\CryptoMethod;

$client = Socket::client(Transport::SSL, 'legacy.example.com', 465);
$client->connect();
$client->crypto(CryptoMethod::TLSv1_2);   // upgrade or pin

For server-side, set the context option before listen():

$server->crypto(CryptoMethod::TLSv1_2);

See Enums for every CryptoMethod case and how it maps to PHP's STREAM_CRYPTO_METHOD_* constants.

Why is the class still here?

The interface symmetry is worth more than the deduplication. Code that selects a transport by configuration value (tls vs ssl) maps trivially onto the Transport enum. Removing one or the other would force every caller to special-case.

See also

• Transport TLS — the canonical reference. Everything there applies to SSL.
• SSL Context Options — every key option() accepts.
• Recipe SMTP Client — a runnable example using Transport::SSL against port 465.