Setting firewall tutorial on Android device. Android default allows all connections from all Internet applications without imposing constraints. This, although at first glance seems practical (for example, we should not worry about condecer explicit access to certain applications or open ports for connection) also has many disadvantages since, for example, any application to your own servers and just connect that we do not care for certain reasons.
There are many applications that function as a firewall for Android, some free and others pay. In this tutorial we are going to talk about AFwall + a free firewall for our Android device, without advertising and open source. The first thing to do is download the application from the Play Store. It is also available at other stores as F-Droid applications, application store only specially designed to offer free applications for Android open source.
Once downloaded and installed the run. We ask root permissions (since iptables are protected by the system), we give it and see the main program window.
We highlight three parts in this window:
Title: the top of the window.
Mode: just below title.
Applications: the biggest part of the window.
The first thing to adjust is the "Mode". You can select a whitelist (block all applications and allow only selected) or a blacklist (all connections are allowed except those selected).
The best option is to select the blacklist, that is, allow Internet access to all applications except those who want to block manually. The white list, but offers more privacy, can cause problems with Android because if we prevent Internet access to certain modules can cause system instability.
Select the blacklist and it's time to choose the applications that will block and allow. We see 3 frames in each application. Each serves to block the Internet connection of a given network (Wi-Fi, Data, Roaming).
The first square block connections marked applications in Wi-Fi networks in a LAN
The second picture block connections applications in a Wi-Fi network.
The third frame connection block via the data network.
All we do then is select the applications you do not want to connect to the Internet through these interfaces, for example, can block games that are not connected from the data network (and not needlessly consume traffic ) and only allow other applications to connect through the data network rather than Wi-Fi network.
If you select all the boxes the application will be completely blocked and will not generate any network traffic.
Once selected applications only thing left for us is to activate the firewall. We open the menu and select "Enable Firewall". Automatically firewall rules specified in our Android device and from next device reset these rules come into force shall apply.