title: listen on port 80 but can't access from public using nginx on centos 7.1
body: <pre><code>Active Internet connections (only servers)
  Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
  tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      16146/nginx: master
  </code></pre>
  
  <p>nginx did listen to port 80. Here is my config in <code>/etc/nginx/conf.d/default.conf</code></p>
  
  <pre><code>server {
      listen       80;
      server_name  _;
  
      #charset koi8-r;
      #access_log  /var/log/nginx/log/host.access.log  main;
  
      location / {
          root   /usr/share/nginx/html;
          index  index.html index.htm;
      }
  
      #error_page  404              /404.html;
  
      # redirect server error pages to the static page /50x.html
      #
      error_page   500 502 503 504  /50x.html;
      location = /50x.html {
          root   /usr/share/nginx/html;
      }
  
      # proxy the PHP scripts to Apache listening on 127.0.0.1:80
      #
      #location ~ \.php$ { ...
  </code></pre>
  
  <p>I'm running nginx on cloud host with a public ip, but I can't access that ip from public network because connection timeout.</p>