title: netstat -t doesn't show connections but netstat -nt does
body: <p>I was using <code>netstat</code> to check tcp connections.
  When I try <code>netstat -t | grep 210</code>,  it doesn't show me any connection (the output is empty), but when I try <code>netstat -nt | grep 210</code>, it shows me what I want : </p>
  
  <pre><code>tcp6       0      0 192.168.0.21:56517      192.168.0.210:9999   ESTABLISHED
  tcp6       0      0 192.168.0.21:56520      192.168.0.210:9999   ESTABLISHED
  </code></pre>
  
  <p>I checked the man page of <code>netstat -n</code>, it says "<em>Show numerical addresses instead of trying to determine symbolic host, port or user names.</em>".  </p>
  
  <p>So I am suspecting in the result it shows host name instead.  So I am checking the result of <code>netstat -t</code>,  the result looks like : </p>
  
  <pre><code>tcp6 0 0 localhost:55231 ip-192-168-0-37 ESTABLISHED
  tcp6 0 0 localhost:55232 ip-192-168-0-38 ESTABLISHED
  ...
  </code></pre>
  
  <p>unfortunately I didn't find any item related to the ip <code>192.168.0.210</code>.</p>
  
  <p>Will very appreciate it if any one has a clue what happened...</p>