Comment 6 for bug 318301

Please post the output of the following command:
sudo iptables -L

I discovered something interesting by the way: "ufw" (uncomplicated firewall) seems to come by default on Ubuntu since v8.04:
https://wiki.ubuntu.com/UbuntuFirewall
https://wiki.ubuntu.com/HardyHeron/Alpha4#Firewall

So another thing you could try is this:
sudo ufw disable

Note that you can also install "gufw" to configure ufw through a GUI:
http://www.ubuntugeek.com/gufw-simple-gui-for-ufw-uncomplicated-firewall.html

Concerning changes made to the system by webcontentcontrol:
By default, changes are only made to files from the dansguardian, tinyproxy and firehol packages.
If you locked the firefox proxy settings, changes are made to: /etc/firefox-3.0/pref/firefox.js
If you locked WPA interfaces, changes are made to: /etc/wpa_supplicant/ifupdown.sh

More info:
http://www.netfilter.org/
https://help.ubuntu.com/community/IptablesHowTo
https://launchpad.net/ufw
http://gufw.tuxfamily.org/index.html
http://www.ubuntugeek.com/ufw-uncomplicated-firewall-for-ubuntu-hardy.html