title: Charles Proxy and Interceptor are not tracking any http request in Ubuntu
body: <p>I can't seem to get any activity showing on anything relating to HTTP/proxy requests in Ubuntu.</p>
  
  <p>I downloaded Charles Proxy first, opened it, but shows nothing.
  Then I tried Interceptor (Chrome extension), also nothing.</p>
  
  <p>Having a look at my Ubuntu settings, it's entirely possible I'm supposed to configure something in here, in support of these options, but it's not documented at all.</p>
  
  <p><a href="https://i.stack.imgur.com/8pS70.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8pS70.png" alt="enter image description here"></a></p>
  
  <p><strong>How I can go about listening to network requests, intercepting them and serving other/mock json when they happen?</strong></p>