Use Fiddler Classic as a Reverse Proxy

Configure Fiddler Classic as Reverse Proxy

To use this method, the hostname for the request to reroute must be 127.0.0.1:8888, localhost:8888, [::1]:8888, or the machine's NETBIOS hostname on port 8888.

1. Click Tools > Options. Ensure Allow remote clients to connect is checked.

   

2. Close Fiddler Classic.

3. Start REGEDIT.

4. Create a new DWORD named ReverseProxyForPort inside HKEY_CURRENT_USER\SOFTWARE\Microsoft\Fiddler2.

5. Set the DWORD to the local port where Fiddler Classic will re-route inbound traffic (usually port 80 for a standard HTTP server).

6. Restart Fiddler Classic.

7. In a browser, go to http://127.0.0.1:8888.

Write a FiddlerScript Rule

1. Click Tools > Options. Ensure Allow remote clients to connect is checked.

   

2. Click Tools > Options, and ensure the "Allow remote clients to connect" checkbox is checked.

3. Restart Fiddler Classic if prompted.

4. Click Rules > Customize Rules.

5. Inside the OnBeforeRequest handler*, add a new line of code:

   if (oSession.host.toLowerCase() == "webserver:8888") oSession.host = "webserver:80";
   

6. Using a browser on the client machine, go to http://webserver:8888.

Configure Fiddler Classic to Listen to Client Application Target Port

1. Reconfigure your target server to listen on a different port. For example, if a web server runs on port 80, reconfigure it to run on port 81.

2. Click Tools > Options....

3. Click Connections.

4. Type the client's target port number next to Fiddler listens to port:

   

5. Configure Fiddler Classic as a reverse proxy or write a FiddlerScript Rule to re-route traffic to the target server's new port (described above).