AFWall+ is a fork of the DroidWall front-end for the iptables Linux firewall, allowing you to configure without having to bring up a Terminal app. You may want to use it for security reasons, restrict data usage if you don't have an unlimited data plan, save battery power, or even just block ads on some of your apps. AFWall+ lets you toggle the firewall on and off, allow or disallow WiFi and 3G traffic for each app on your device and set a password to protect your settings. Advanced users can also manually define custom iptables rules.