⭐ Firewall allows you to block apps from accessing the Internet without root requirement. ⭕ Firewall uses the Android VpnService to route traffic to itself, the apps access the Internet will be filtered on-device instead of on a server. ⭕ The reason VpnService is needed: - Users can allow/block the apps access the Internet, the technical for this solution is using VpnService for control the Internet access - Firewall uses the Android VpnService to block the Internet access for apps on devi