Android operating system may sometime involve many Gaps. Not so far, Stagefright Gap has been propagated in many devices working with Android operating system.
For that, in this article, I’ll show you one of the best firewall you can setup on your devise if it is 5.0 versions or better. The firewall is called NetGuard - no-root firewall and does not require having privileges of root. The download link below this article .
The first thing you should do after installing the firewall is to accept the VPN privileges so that the firewall could control all the communications from and to devise. Furthermore, the firewall will allow you controlling the internet consumption of android applications.
As a firewall, NetGuard will inspect and discard any dangerous software that may damage your devise or spy your activities or personal data by disconnecting it.
Download Link : NetGuard