title: Jenkins - (private subnet) WebHook with Github does not trigger automatic build
body: <p><strong>Problem :</strong> <br/><br/>
  I am working on a CI setup to configure github - Jenkins web hook for triggering builds with code commits on github. Below are the current configuration details</p>
  
  <ul>
  <li>My Jenkins is inside an AWS private subnet</li>
  <li>I have plugin: "GitHub Web Hook" configured with API URL, Username and OAuth token, Test Credentials gives a success message.</li>
  <li>I have "Build when a change is pushed to GitHub" selected under "Build Triggers"</li>
  </ul>
  
  <p>Jenkins job works perfectly with the manual build. But it does not work (automatic build trigger) when a code commit is done on the github.</p>
  
  <p><strong>Need Help on:</strong></p>
  
  <ol>
  <li>How can I debug in detail about this situation, if the "Git hub webhook" configuration test worked, can I say git hub is able to connect to my Jenkins which is in private or it does something else to test ?</li>
  <li>Please rectify / guide on the steps to get it working</li>
  </ol>