<b>N.B</b> Development of this app ceased in mid 2012. Use https://f-droid.org/packages/dev.ukanth.ufirewall instead. Tap the tab at the top to switch between whitelist and blacklist mode. Tap Menu and Apply Changes to apply. Recommended platforms are Android 1.6 to 2.3.7. Requires root: Yes. iptables (the firewall itself) has to be run as root.