Not sure if I understand your question correctly. HTTPfox works fine on Firefox on Linux (including Ubuntu) as far as I know.
If you're looking for something more general, outside the browser, Wireshark can listen to the traffic happening on your network (in particular on your machine). It has a comprehensive set of protocol analysers, including HTTP.
Since it doesn't run within the browser (or other application), it won't be able to see what's going on within the application itself. In particular, it will be harder look into HTTPS traffic, although with some configurations (provided you have the server's private key and you're using a subset of cipher suites Wireshark can decipher), you'll also be able to look into SSL/TLS-encrypted traffic (and the HTTP analyser will work on top of this, in this case).