mitmproxy on Ubuntu 20.04+

by Andrew Stilliard

mitmproxy is a free and open source interactive HTTPS proxy.

To quickly get this up and running on Ubuntu 19.04 (Updated and tested in 20.04 & 21.04).

Install mitmproxy

sudo apt install mitmproxy

This should install the latest version, if not you can get the binary direct from the website: https://mitmproxy.org

Start the proxy

For this demo we'll use port 8881 for the proxy but this can be anything not already in use.

For the command line version: 

sudo mitmproxy -p 8881

Or the web UI version 

sudo mitmweb -p 8881 --web-port 8882

Using 8882 as the web port, this will let you open http://127.0.0.1:8882/ to watch the traffic through but again this can be any port you like.

Or a socks5 proxy 

sudo mitmproxy -p 8881 -m socks5  
or  
sudo mitmweb -p 8881 -m socks5 --web-port 8882

Setup proxy

Open your Network settings and click to edit your Network Proxy.

Can also be found by going through chrome://settings/?search=proxy and clicking Open proxy settings

Set to Manual & set both your HTTP & HTTP proxies to localhost port 8881.

Setup SSL/TLS certificate for HTTPS support

This step is only needed the first time it's run.

Go to http://mitm.it/pem/cert which will download the certificate.

Then to import this into Chrome, head to chrome://settings/certificates and click Authorities & then click Import to select the downloaded certificate.

You may find this doesn't kick in with your existing Chrome session so try it our in Incognito/Private/Guest.

Enjoy

If using the command line version the requests will be listed as they come in. Use the up and down arrows to navigate around, press enter to view inside a request and then left & right between the tabs. You can also use your mouse to click the requests and tabs if easier. Then press q to go back to the requests list. Ctrl+c as often to exit.

Or if you're using the web UI, simply head over to http://127.0.0.1:8882/ and it'll start listing requests as you navigate the web.

Remember when you're done to disable your Network proxy setting when you're done with the proxy.