如何确认Linux共享主机是否支持WebSocket及SSH连接

Hey there, let's walk through practical ways to check if your Linux shared host is blocking SSH or WebSocket functionality—these steps should help you narrow down the issue:

• Direct connection attempt: Fire up your terminal (or use Putty/another SSH client) and run:

  ssh your_username@your_hostname_or_ip
  

  Pay close attention to the error message:
  • Connection refused: Likely means port 22 (default SSH port) is blocked by the host's firewall.
  • Connection timed out: The host is either unreachable or actively dropping SSH traffic.
  • Permission denied: This is usually an authentication issue (wrong username/password/key), not a block—double-check your credentials first.
• Port status check: Use an online port checker tool to verify if port 22 is open on your host's IP. If it shows as closed, the host is probably blocking it.
• Ask support directly: Sometimes the fastest way is to shoot a message to your host's support team—ask explicitly if SSH access is allowed on your plan, and if port 22 is unblocked.

Shared hosts often restrict WebSocket access either via port blocks, disabled extensions, or limits on persistent processes. Try these tests:

• Simple WebSocket client test: Use an online WebSocket testing tool to connect to a test endpoint (you can set up a minimal one using Ratchet, or use a public test server if needed). If the connection fails with a "connection closed" or "timeout" error, it might be blocked.
• Check PHP extensions: Create a phpinfo.php file with this content:

  <?php phpinfo(); ?>
  

  Access it via your browser, then search for sockets—if the extension isn't enabled, Ratchet and other WebSocket libraries won't work. Also look for any entries related to disable_functions that might block socket-related functions.
• Test a minimal WebSocket server: Write a tiny Ratchet-based server script (like the example below), upload it to your host, and try to run it via SSH (if you can get access) or a cron job (though shared hosts often block persistent processes):

  <?php
  require 'vendor/autoload.php';
  
  use Ratchet\MessageComponentInterface;
  use Ratchet\ConnectionInterface;
  use Ratchet\Server\IoServer;
  use Ratchet\Http\HttpServer;
  use Ratchet\WebSocket\WsServer;
  
  class TestServer implements MessageComponentInterface {
      public function onOpen(ConnectionInterface $conn) {}
      public function onMessage(ConnectionInterface $from, $msg) {}
      public function onClose(ConnectionInterface $conn) {}
      public function onError(ConnectionInterface $conn, \Exception $e) {}
  }
  
  $server = IoServer::factory(
      new HttpServer(new WsServer(new TestServer())),
      8080
  );
  
  $server->run();
  

  If you get errors like Permission denied when trying to bind to port 8080, or the process gets killed immediately, the host is likely restricting either port access or persistent process execution.
• Check port restrictions: WebSocket can run on standard HTTP/HTTPS ports (80/443) if you use a reverse proxy, but many shared hosts block non-standard ports like 8080. Try configuring your WebSocket server to use port 80/443 (if allowed) and test again.

A quick note: Even if ports are open, many shared hosts don't allow long-running processes (which WebSocket servers require) as part of their shared hosting plans. So you might pass the connection tests but still can't keep the server running.

内容的提问来源于stack exchange，提问作者Wizards