title: Is it possible to connect to Cloud SQL Proxy via Host Compute Engine VM's Internal or External IP?
body: <p>I am testing the following configuration.</p>
  
  <ul>
  <li>Cloud SQL (tetsql-1) in Region X Zone A</li>
  <li>A Compute Engine VM (TestVM-1) in the same Region X Zone A. OS is Centos 7</li>
  <li>Compute Engine VM is running cloud SQL proxy on non default port (9090)</li>
  </ul>
  
  <p>With the above configuration I am able to logon to testsql-1 from TestVM-1 with below command:</p>
  
  <pre><code>  `mysql -h 127.0.0.1 --port 9090 -u testuser -D testDB -p`
  </code></pre>
  
  <p>However I am not able use the internal IP of TestVM-1 in the above command. It gives an error.</p>
  
  <p>Another observation is I am able to do <code>telnet 127.0.0.1 9090</code> but when I try <code>telnet &lt;VM -Internal-IP&gt; 9090</code> returns a connection refused error.</p>
  
  <p>Does anyone know if this is expected behaviour? If this is expected, why is it so?</p>