Extract SSL SHA256 Fingerprint

ssh-sha256.php

#!/usr/bin/env php
<?php
/**
 * Get SHA5 digest for remote SSL cert
 *
 * @param string $host Domain or IP address
 * @param int $port Port number, default 443.
 * @return string Hexadecimal in lowercase
 */
function getSHA256Digest($host, $port = 443) {
    // Since it is connecting to VPN by IP, verifying domain name will failed.
    $contextCreate = stream_context_create(["ssl" => [
        "capture_peer_cert" => true,
        // Disable verifications
        "verify_peer" => false,
        "verify_peer_name" => false
    ]]);

    $res = stream_socket_client("ssl://{$host}:{$port}", $errno, $errstr, 30, STREAM_CLIENT_CONNECT, $contextCreate);
    $context = stream_context_get_params($res);

    return openssl_x509_fingerprint($context["options"]["ssl"]["peer_certificate"], "sha256");
}

function main() {
    global $argc, $argv;
    $hashString = null;

    if ($argc == 1) {
        echo "Usage: {$argv[0]} <host> [<port>]\n";
        echo "Usage example: {$argv[0]} 1.2.3.4\n";
        echo "Usage example: {$argv[0]} 1.2.3.4 443\n";
        return;
    }
    else if ($argc == 2) { // Port number not specified
        $hashString = getSHA256Digest($argv[1]);
    }
    else {
        $hashString = getSHA256Digest($argv[1], $argv[2]);
    }

    echo "{$hashString}\n";
}

if (php_sapi_name() == "cli") {
    main();
}