I have a rooted Xperia M dual (C2005) with factory firmare (4.2.2). Installed Afwall+ and blocked all network activity except Firefox and K9mail.
But there is still network usage (Android OS).
There is a blog post about this, but I can't link it. Google on "How to debug/examine data usage leaks in Android using iptables"
Does somebody have an idea how can I block these types of data transfer?