I currently use openDNS to filter user's web requests however they can often bypass this filtering by finding a proxy server (not yet on the openDNS block list) and configuring firefox to use it. Is there anyway I can just lock firefox so this non-admin user can't switch to a proxy full stop? or perhaps somehow stop them using a proxy with iptables..
EDIT: Tested this on firefox 18. The *.js file name may be called all.js in older firefoxes. I'm not that familiar with firefox, that i could say if adding your own all.js would work too
create a text file containing :
The byteshift that file into mozilla.cfg with offset 13. Easiest is to use : http://www.alain.knaff.lu/howto/MozillaCustomization/cgi/byteshf.cgi
Then copy that mozilla.cfg into the directory where mozilla exe is located.
and add line
then reboot firefox
Editing the channel-pref requires opening as admin or giving r/w to standard users. You can edit several other configs like this. List found at: FAQs:_About:config_Entries">http://kb.mozillazine.org/Firefox_:FAQs:_About:config_Entries