Awesome

Android Firewall

NetGuard is possibly the first free and open source no-root firewall for Android.

Features

No root required
Simple to use
Free of charge
Open source
No extra battery usage
No calling home
No tracking or analytics
No ads
IPv4/IPv6 TCP/UDP supported

NetGuard doesn't even require the internet permission!

Usage

Enable the firewall using the switch in the action bar
Allow/deny WiFi/mobile internet access using the icons at the right side of the application list

Permissions

ACCESS_NETWORK_STATE: to check if the device is connected to the internet through WiFi
RECEIVE_BOOT_COMPLETED: to start the firewall when starting the device

Frequently Asked Questions (FAQ)

<a name="FAQ1"></a> (1) Can Android Firewall completely protect my privacy?

No - nothing can completely protect your privacy. will do its best, but it is limited by the fact it must use the VPN service. This is the trade-off required to make a firewall which does not require root access. The firewall can only start when Android "allows" it to start, so it will not offer protection during early boot-up (although your network may not be loaded at that time). It will, however, be much better than nothing, especially if you are not rebooting often.

If you want to protect yourself more, you can (at least in theory) disable WiFi and mobile data before rebooting, and only enable them on reboot, after the firewall service has started (and the small key icon is visible in the status bar).

Thanks @pulser

<a name="FAQ2"></a> (2) Can I use VPN applications while using Android Firewall?

If the VPN application is using the VPN service, then no, because Android Firewall needs to use this service, and Android allows only one application at a time to use this service.

<a name="FAQ3"></a> (3) Can I use Android Firewall on any Android version?

No, because the method addDisallowedApplication is being used, the minimum required Android version is 5.0 (Lollipop).

<a name="FAQ4"></a> (4) Will Android Firewall use extra battery power?

No, unlike most of the similar closed source alternatives.

<a name="FAQ5"></a> (5) Can you add selective allowing/blocking IP addresses?

Unfortunately this is not possible without using significant battery power and adding a lot of complex code to do network translation from OSI layer 3 to layer 4 (and thus implementing a TCP/IP stack), which will inevitably introduce bugs as well. This is how most (all?) other no root firewalls work. Android Firewall is unique, because it doesn't implement a TCP/IP stack and is therefore both highly efficient and simple.

For more advanced use cases while not sacrificing battery usage, rooting and using a iptables based firewall, like AFWall+ might be a better option.

Support

Questions: please use this XDA-Developers forum thread
Feature requests and bugs: please report an issue on GitHub

Please do not use GitHub for questions.

Contributing

Translations:

Translations to other languages are welcomed
Check if the language is supported by Android and find its locale
Copy this file to the correct locale folder
Translate the strings in the copied file and omit all lines with translatable="false"
Create a pull request on GitHub for the new/updated translation

Please note that you agree to the license below by contributing, including the copyright.

License

GNU General Public License version 3

This file is part of Android Firewall.

Android Firewall is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your discretion) any later version.

Android Firewall is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with NetGuard. If not, see http://www.gnu.org/licenses/.