* Launch with firefox -ProfileManager , create new profile, and launch
firefox with that (new) profile
* Go Preferences -> Advanced -> Network -> Connection -> Settings
* Once choose "Manual proxy configuration", set random http proxy, change port
(like HTTP Proxy: aaaaaa Port: 8080).
* Then choose *again* "Use system proxy settings"
* Click OK
* Now open some http:// page like http://www.google.com/
Step to reproduce:
* Launch with firefox -ProfileManager , create new profile, and launch www.google. com/
firefox with that (new) profile
* Go Preferences -> Advanced -> Network -> Connection -> Settings
* Once choose "Manual proxy configuration", set random http proxy, change port
(like HTTP Proxy: aaaaaa Port: 8080).
* Then choose *again* "Use system proxy settings"
* Click OK
* Now open some http:// page like http://