How to Identify Reverse Proxy Servers

Find reverse proxies when troubleshooting Web client connectivity.

A reverse proxy server is typically installed between an Internet connection and a group of servers, such as Web servers, to provide load-balancing, caching, encryption services and additional security for the Web servers it services. If a Web client is having trouble connecting to a Web server, knowing if the Web client is connecting to a reverse proxy server is an important step toward finding the root cause of the issue. Identify reverse proxy servers using a telnet client.

Instructions

1. Click the "Start" button on the Windows 7 PC desktop and click the "Search" box. Type "cmd" in the "Search" box and tap the "Enter" key. The command line window will appear.

2. Type "telnet x.x.x.x:80" replacing the "x.x.x.x" with the system you are testing to determine whether or not it is a reverse proxy server.

3. Press the "Enter" key. If the telnet client is able to establish a connection, type "HEAD / HTTP/1.0" and press the "Enter" key. If the command line output displays an "HTTP/ 1.1 200 OK" message, then the telnet client has connected to a Web server service. If the command line output displays an "HTTP/ 1.1 403 Forbidden" message, then proceed to the next step.

4. Type "HEAD HTTP/1.1 Host: www.hostname.org" replacing the "www.hostname.org" with the actual hostname of a system being serviced by the reverse proxy. Press the "Enter" key. If the command line output displays an "HTTP/1.1 200 OK" message, then the telnet client is connected to a reverse proxy.

References

• "Network Security Assessment"; Chris McNab; 2008