title: Setting proxy port, why cannot I use another port except 9000?
body: <p>I need web server and try Nginx and Lighttpd. I try to set proxy path and can use both. But it doesn't works if I use port 8080, 9001, 19000 ... It works well only under port 9000. It is same both case of Nginx and Lighttpd.  </p>
  
  <p>My environment<br>
  host OS: Windows 10<br>
  VirtualBox 5.2<br>
  guest OS: CentOS 7</p>
  
  <pre><code>Nginx
      location / {
              proxy_pass http://127.0.0.1:9000;
      }  
  
  
  Lighttpd
      proxy.server = ("/" =&gt; ((
          "host" =&gt; "127.0.0.1",
          "port" =&gt; 9000,
      )))
  </code></pre>
  
  <p>Need I set OS environment?<br>
  Why does it work only in case of port 9000?</p>
  
  <h2>The mean of "work well" is like next.</h2>
  
  <p>Server is coded in socket of C language.</p>
  
  <p>I enter 192.168.0.111 in Chrome to connect to server. After accepting, server receive message from socket_fd and send message to socket_fd.   </p>
  
  <pre><code>recv(socket_fd, buf, 3999, 0);
  send(socket_fd, "TTT === TTT", strlen("TTT === TTT"), 0);
  </code></pre>
  
  <p>Message from client is followings</p>
  
  <pre><code>GET / HTTP/1.0
  Host: 127.0.0.1:9000
  Connection: close
  Cache-Control: max-age=0
  Upgrade-Insecure-Requests: 1
  User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.87 Safari/537.36
  Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8
  Accept-Encoding: gzip, deflate
  Accept-Language: ko-KR,ko;q=0.9,en-US;q=0.8,en;q=0.7
  Cookie: TRACKID=c9130c835a38d41a826a34a5939cf8c5
  </code></pre>
  
  <p>Message from server is followings.</p>
  
  <pre><code>TTT === TTT
  </code></pre>
  
  <p>This message is displayed in Chrome.</p>
  
  <hr>
  
  <p>Thank you in advance.</p>