Android - How to prevent an application from accessing to the internet by another application

Question

TrafficStats give us the information about which application consumes how bandwith, well.

I would like to write an application which disables/enables some other application's internet usage whenever needed.

I see there are some google play applications which are doing that but how?

Answer 1

private void setMobileDataEnabled(Context context, boolean enabled) throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
    final ConnectivityManager conman = (ConnectivityManager)  context.getSystemService(Context.CONNECTIVITY_SERVICE);
    final Class conmanClass = Class.forName(conman.getClass().getName());
    final Field connectivityManagerField = conmanClass.getDeclaredField("mService");
    connectivityManagerField.setAccessible(true);
    final Object connectivityManager = connectivityManagerField.get(conman);
    final Class connectivityManagerClass =  Class.forName(connectivityManager.getClass().getName());
    final Method setMobileDataEnabledMethod = connectivityManagerClass.getDeclaredMethod("setMobileDataEnabled", Boolean.TYPE);
    setMobileDataEnabledMethod.setAccessible(true);

    setMobileDataEnabledMethod.invoke(connectivityManager, enabled);
}

Dont forget to add this line to your manifest file

<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"/>

Answer 2

for that consider of using iptables

good example (showing how to write a firewall program) is orWall

Put your apps behind Orbot and block all unwanted traffic in one go.

Orwall page also pointing to GitHub source Codes

"This is not a solution. This is just another program doing this thing. I am asking how to code a program like this.. Which can enable or disable internet access for another application. So -1"

do u know how to read?

iptables is a user-space application program that allows a system administrator to configure the tables provided by the Linux kernel firewall (implemented as different Netfilter modules) and the chains and rules it stores. Different kernel modules and programs are currently used for different protocols; iptables applies to IPv4, ip6tables to IPv6, arptables to ARP, and ebtables to Ethernet frames.

iptables requires elevated privileges to operate and must be executed by user root, otherwise it fails to function. On most Linux systems, iptables is installed as /usr/sbin/iptables and documented in its man pages, which can be opened using man iptables when installed. It may also be found in /sbin/iptables, but since iptables is more like a service rather than an "essential binary", the preferred location remains /usr/sbin.

The term iptables is also commonly used to inclusively refer to the kernel-level components. x_tables is the name of the kernel module carrying the shared code portion used by all four modules that also provides the API used for extensions; subsequently, Xtables is more or less used to refer to the entire firewall (v4, v6, arp, and eb) architecture.

The successor of iptables is nftables, which was merged into the Linux kernel mainline in kernel version 3.13, which was released on 19 January 2014

origin: iptables - wikipedia