It is. But the developer keep it secret.
But it is easy to do.
1. Download one of hosts files below.
AdAway Blocks mobile advertising and analytics networks.
Dan Pollock's Hosts Blocks spyware, pop-ups, trackers, exploits, and advertisements.
HostsFile.org Hosts Blocks advertisements, trackers, gambling, and adult websites.
hpHosts Includes hpHosts Exploits, hpHosts Hijacking, hpHosts Malware, and hpHosts Phishing. Blocks advertisements, trackers, and malware.
hpHosts ad and tracking Blocks advertisements and trackers.
2. Rename downloaded file to: domains.csv
3. Move/Copy domains.csv to folder /sdcard/firewall or /storage/emulated/0/firewall
4. Open NoRoot Data Firewall app. Tap 3 white dots in top right corner, then tap Backup/Restore, then tap Restore.
I have just launched a "NoRoot Data Firewall" app in GooglePlay recently.
It has the following features:
* NO ROOT REQUIRED FIREWALL.
* Control the access permission for each app to access internet with mobile network and WIFI.
* Support to only blocking background data and let foreground data go.
* Record, analyze and sort the data usage for each app.
* Analyze the accessed websites for each app.
* Startup automatically.
* Capture packets(Sniffer).
* Manage app permissions for 4.3, 4.4 devices.
The google play app is here: https://play.google.com/store/apps/details?id=com.jianjia.firewall
Hope you like it.