Transparent mode redirects to host itself

Question

I'm new to mitmproxy and and I'm probably doing something wrong.

I'm running Mitmproxy in transparent mode on Ubuntu and followed the steps on https://docs.mitmproxy.org/stable/howto-transparent/. Its IP is 10.50.10.117.

I then added a line to /etc/hosts in my client machine (10.50.10.116) that points to the mitmproxy server for a test domain (example.com). So this is only on the client machine, and not on the machine running mitmproxy.

Then when I execute 'curl http://example.com' on the client machine, I see the request get to mitmproxy but it errors out with:

10.50.10.116:60936: GET http://example.com/
    Host: example.com
    User-Agent: curl/7.68.0
    Accept: */*
 << Server connection to ('10.50.10.117', 80) failed: Error connecting to "10.50.10.117": [Errno 111] Connection refused

So mitmproxy is trying to connect to its own host on port 80. Why is it not proxying the request to the real example.com?

Thanks.

Henry

Answer 1

https://docs.mitmproxy.org/stable/concepts-modes/#transparent-proxy has an illustration that shows your problem: The TCP packet's destination IP address is mitmproxy and not the actual target. Transparent mode expects Layer 2 redirection.

It looks like you want to run mitmproxy as a reverse proxy. Alternatively, starting with mitmproxy 7 (currently only available as development snapshots, but I encourage you to try them out), you can run it in regular mode and it will pick up host headers for the target information.