mitmproxy on foosel.nethttps://foosel.net/tags/mitmproxy/Recent content in mitmproxy on foosel.netHugoen-usGina Häußge (foosel)Tue, 12 Mar 2024 00:00:00 +0000How to quickly create a header modifying reverse proxy with mitmproxyhttps://foosel.net/til/how-to-quickly-create-a-header-modifying-reverse-proxy-with-mitmproxy/Tue, 12 Mar 2024 00:00:00 +0000https://foosel.net/til/how-to-quickly-create-a-header-modifying-reverse-proxy-with-mitmproxy/<p>I&rsquo;m currently in the process of testing some changes on OctoPrint involving its automatic user login via request headers, and for that needed to quickly set up a reverse proxy that would modify the headers of the requests going to the development server for some quick testing.</p> <p>Specifically, I wanted a quick CLI tool that would allow me to set up a reverse proxy listening on port 5555, forwarding to <code>http://localhost:5000</code> while also setting the headers <code>X-Remote-User</code> to <code>remote</code> and <code>X-Remote-Host</code> to <code>localhost:5555</code>.</p>I’m currently in the process of testing some changes on OctoPrint involving its automatic user login via request headers, and for that needed to quickly set up a reverse proxy that would modify the headers of the requests going to the development server for some quick testing.

Specifically, I wanted a quick CLI tool that would allow me to set up a reverse proxy listening on port 5555, forwarding to http://localhost:5000 while also setting the headers X-Remote-User to remote and X-Remote-Host to localhost:5555.

Enter mitmproxy, or more specifically its mitmdump tool, which turned out to be a great tool for this job.

All I needed was to run the following command:

mitmdump --mode reverse:http://localhost:5000@5555 --modify-headers "/X-Remote-User/remote" --modify-headers "/X-Forwarded-Host/localhost:5555"

This does the following:

  • --mode reverse:http://localhost:5000@5555 sets up a reverse proxy listening on port 5555, forwarding to http://localhost:5000
  • --modify-headers "/X-Remote-User/remote" sets the X-Remote-User header to remote
  • --modify-headers "/X-Forwarded-Host/localhost:5555" sets the X-Forwarded-Host header to localhost:5555

With that the reverse proxy test page in OctoPrint turned all green and I could test my changes without having to set up an actual reverse proxy in front of the development server.

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