title: UFW firewall is not working on Ubuntu in DigitalOcean
body: <p>In my DigitalOcean (DO) droplet I installed this image: <strong>Ubuntu Docker 17.12.0~ce on 16.04</strong> (which is available on ** DO website > droplet> destroy> rebuild droplet**) , in ssh (after user configuration), I run </p>
  
  <pre><code>sudo ufw default deny incoming
  sudo ufw default allow outgoing
  sudo ufw enable
  sudo ufw status verbose
  </code></pre>
  
  <p>and get:</p>
  
  <pre><code>Status: active
  Logging: on (low)
  Default: deny (incoming), allow (outgoing), allow (routed)
  New profiles: skip
  
  To                         Action      From
  --                         ------      ----
  22                         LIMIT IN    Anywhere                  
  2375/tcp                   ALLOW IN    Anywhere                  
  2376/tcp                   ALLOW IN    Anywhere                  
  22 (v6)                    LIMIT IN    Anywhere (v6)             
  2375/tcp (v6)              ALLOW IN    Anywhere (v6)             
  2376/tcp (v6)              ALLOW IN    Anywhere (v6) 
  </code></pre>
  
  <p>As you see, I don't allow any connections on port 80 (http). Ok to test that firewall really works I run following docker:</p>
  
  <pre><code>sudo docker run -d -p 80:80 -e ENABLE_IPV6=true -v /var/run/docker.sock:/tmp/docker.sock:ro jwilder/nginx-proxy:alpine
  </code></pre>
  
  <p>But when I go to chrome and type my droplet IP I see nginx response (!!!)</p>
  
  <p>I try this also for Ubuntu 17 image (with docker installation by hand) but still get the same problem.</p>
  
  <p><em>Conclusion</em>: ufw firewall doesn't work at all in Ubuntu</p>
  
  <p><strong>Question</strong>: how to configure ufw/Ubuntu to fix this problem?</p>