HOWTO: OpenWRT and Fiddler for HTTP and HTTPS Transparent Proxy traffic capture – Part 2


  • Setup a Hyper-V test lab for capturing traffic from an Android client.
  • Use OpenWRT as the routing gateway for the private VM network and Transparent Proxy HTTP and HTTPS traffic to Fiddler.
  • Config Fidder for traffic capture.

See Also:

Configuring OpenWRT for Transpart Proxy

  • Create Port Forward / Pre-routing rules for TCP port 80 and 443 to forward traffic to Fiddler.
    • Assuming Fiddler is running at, port 8888 for HTTP proxy and 8443 for HTTPS proxy.
    • Exclude the Fiddler machine from the port forward.

  • Create Source NAT / Post-routing rule


  • OR write the rules in the Firewall Custom Rules page.


Configuring Fiddler for Transpart Proxy

  • Enable “Allow remote computers to connect” in Fiddler Options and open corresponding ports in the Windows Firewall.

  • Use the command “!listen 8443 your_dummy_CN” to make Fiddler to listen to port 8443 for HTTPS proxy.
    • The dummy CN value is important. Without the CN value Fiddler will not handle the HTTPS handshake.

  • Use the command “prefs set true” to make Fiddler to generate the cert with CN to match the incoming request.

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