We don't usually find a firewall on Android, but that doesn't mean that they don't exist or that they can't be very useful if you are very security-conscious regarding your Android. Among other options, you will find NoRoot Firewall, an application that, as its name suggests, doesn't need any superuser permissions and which will help you monitor and control all of the connections established by your device.

NoRoot Firewall 4.0.2 Total control of your Internet connection

This tool will help you find out what apps are connecting to the Internet and when. This will let you know whether it is just normal activity or whether it is a risk to your privacy. The app can be configured very easily and offers these basic functions:

Restrict connections to the Internet selectively or en bloc.

Filter connections by host or domain name.

Basic interface layout making it easy to use for any user.

Minimal permissions.

Notification system so that you can always be alert to any suspicious connection.

NoRoot Firewall 4.0.2 Requirements and additional information:

Minimum operating system requirements: Android 5.0.

NoRoot Firewall 4.0.2 NewS

NoRoot Firewall is an application with which you will be able to monitor and control all of those apps and processes that establish Internet connections