Please note that this solution only works for capturing HTTP traffic only!
What you’ll need:
1. DD-WRT router
2. Computer (machine1) with 2 network interface with Charles Proxy installed
3. Computer(machine2) with 1 network interface with ZebraTester installed
4. And of course, device that doesn’t have a configurable proxy setting
A. Connect the DD-WRT router to an existing network (Double NAT is ok) setup as a gateway
B. Set the HTTP redirect to:
a. HTTP Redirect = enable
b. HTTP Destination IP = machine1’s IP
c. HTTP Destination Port = machine1’s Proxy Port (Charles Proxy’s port)
d. HTTP Source Network = IP of device to capture traffic from
C. On machine1 configure Charles Proxy as transparent proxy server and set External Proxy Settings to point to machine 2’s IP for http (https optional)
D. Run ZebraTester on machine2 and verify traffic being received by looking at the ZT console. When done with configuration, you can then start recording.