I am trying to pick up HTTP requests from a program but when this program sends http requests, through TCP View I can see that it sends it on my machine's 192.x ip instead of 127.0.0.1 and fiddler is not picking this up. Any clues on how to fix this?
Thanks!
1 Answer, 1 is accepted
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Nick Iliev
Telerik team
answered on 06 Dec 2023, 07:26 AM
Hello,
To use Fiddler Everywhere, you need to ensure that the client application is configured to use the Fiddler proxy. Fiddler Everywhere captures all traffic that goes through the proxy. If the client application is set to use the system proxy, you can use Fiddler's system capturing mode. If the client application is not automatically respecting the system proxy, then you could try to explicitly instruct it to use the Fiddler proxy (by default, at 127.0.0.1:8866). If that option doesn't work you have the option to start the application through the Fiddler's terminal (if that is applicable option for the client application) and capture its traffic as a child process of the terminal.
If none of the above solutions work, please provide more details about the application you are using so that we can offer proper guidance.
Thanks for this response, the terminal has now worked but now the application only sends a connect request and seems to "hang" on that, it never follows up with a get/post request etc. Any clues on how to fix that? Works fine when not run in fiddler just doesn't show up!
Nick Iliev
Telerik team
commented on 07 Dec 2023, 07:36 AM
The CONNECT Tunnel is an HTTP request between the client and the proxy app (in this case, Fiddler Everywhere) and is used to determine which TLS version should be used so that the proxy can complete the TLS handshake with the server. That can only happen if the client app is using the certificate authority (CA) that Fiddler installs in the OS certificate manager application or if it is using the CA explicitly.
The above said that you are seeing the CONNECT Tunnels but not the actual HTTPS requests that must follow, indicating that your client application is not using the Fiddler certificate or the OS certificate manager. That could happen due to misconfiguration of the client application or additional security policy (like certificate pinning) where the application expects and trusts only specific CA and won't work with user-installed CAs.