NetGuard/FAQ.md

NetGuard

Please scroll down if you want to ask a question, request a feature or report a bug.

Frequently Asked Questions (FAQ)

(0) How do I use NetGuard?

• Enable the firewall using the switch in the action bar
• Allow/deny Wi-Fi/mobile internet access using the icons along the right side of the application list

You can use the settings menu to change from blacklist mode (allow all in Settings but block unwanted applications in list) to whitelist mode (block all in Settings but allow favorite applications in list).

• Red/orange/yellow/amber = internet access denied
• Teal/blue/purple/grey = internet access allowd

(1) Can NetGuard completely protect my privacy?

No - nothing can completely protect your privacy. NetGuard 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.

Android N will allow NetGuard to be an Always-On VPN.

If you want to protect yourself more, you can (at least in theory) disable Wi-Fi 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

(2) Can I use another VPN application while using NetGuard

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

(3) Can I use NetGuard on any Android version?

No, the minimum required Android version is 4.0 (KitKat) because NetGuard uses the Android VPN service, which was added in Android 4.0.

(4) Will NetGuard use extra battery power?

If you didn't enable IP filtering, probably not.

However, the network speed graph notification will use extra battery power. This is why the notification is shown only when the screen is on. You can decrease the update frequency using the settings to reduce the battery usage.

(6) Will NetGuard send my internet traffic to an external (VPN) server?

No, depending on the mode of operation basically one of two things will happen with your internet traffic:

• When IP filtering is disabled, blocked internet traffic will be routed into the local VPN which will operate as sinkhole (in effect dropping all blocked traffic)
• When IP filtering is enabled, both blocked and allowed internet traffic will be routed into the local VPN and only allowed traffic will be forwarded to the intended destination (so not to a VPN server)

The Android VPN service is being used to locally route all internet traffic to NetGuard so no root is required to build a firewall application. NetGuard is unlike all other no-root firewalls applications 100% open source, so when you are in doubt you can check the source code yourself.

(7) Why are applications without internet permission shown?

Internet permission can be granted with each application update without user consent. By showing all applications, NetGuard allows you to control internet access even before such an update occurs.

(8) What do I need to enable for the Google Play™ store app to work?

You need 3 packages (applications) enabled (use search in NetGuard to find them quickly):

• com.android.vending (Play store)
• com.google.android.gms (Play services)
• com.android.providers.downloads (Download manager)

Since the Google Play™ store app has a tendency to check for updates or even download them all by itself (even if no account is associated), one can keep it in check by enabling "Allow when device in use" for all 3 of these packages. Click on the down arrow on the left side of an application name and check that option, but leave the network icons set to red (hence blocked).The little human icon will appear for those packages.

Note that NetGuard does not require any Google service to be installed.

(9) Why is the VPN service being restarted?

The VPN service will be restarted when you turn the screen on or off and when connectivity changes (Wi-Fi, mobile) to apply the rules with the conditions 'Allow when screen is on' and 'Block when roaming'.

See here for more details.

(10) Will you provide a Tasker plug-in?

If disabling NetGuard is allowed to Tasker, any application can disabled NetGuard too. Allowing to disable a security application from other applications is not a good idea.

(13) How can I remove the ongoing NetGuard entry in the notification screen?

• Long click the NetGuard notification
• Tap the 'i' icon
• Depending on your device and/or ROMs manufacturer software customizations, you can be directed to either:
  • the App Info screen and you can uncheck 'Show notifications' and agree to the next dialog
  • the App Notifications screen and you can toggle the 'Block' slider to on

Note that, whether or not you get a dialog warning to agree upon, this operation will disable any information or warning notifications from NetGuard as well, like the new application installed notification.

To read about the need for the notification in the first place, see question 24.

Some Android versions display an additional notification, which might include a key icon. This notification can unfortunately not be removed.

(14) Why can't I select OK to approve the VPN connection request?

There might be another (invisible) application on top of the VPN connection request dialog. Some known (screen dimming) applications which can cause this are Lux Brightness, Night Mode and Twilight. To avoid this problem, at least temporary, close all applications and/or services which may be running in the background.

(15) Why won't you support the F-Droid builds?

Because F-Droid doesn't support reproducible builds. Read here why this is important.

Another reason is that F-Droid builds are more often than not outdated, leaving users with an old version with known bugs.

(16) Why are some applications shown dimmed?

Disabled applications and applications without internet permission are shown dimmed.

(17) Why is NetGuard using so much memory?

It isn't, NetGuard doesn't allocate any memory, except a little for displaying the user interface elements. It appeared that on some Android variants the Google Play™ store app connection, using almost 150 MB and needed for in-app donations, is incorrectly attributed to NetGuard instead to the Google Play™ store app.

(18) Why can't I find NetGuard in the Google Play™ store app?

NetGuard requires at least Android 4.0, so it is not available in the Google Play™ store app for devices running older Android versions.

(19) Why does aplication XYZ still have internet access?

If you block internet access for an application, there is no way around it. However, applications could access the internet through other applications. Google Play services is handling push messages for most applications for example. You can prevent this by blocking internet access for the other application as well.

Note that some applications keep trying to access the internet, which is done by sending a connection request packet. This packet goes into the VPN sinkhole when internet access for the application is blocked. This packet consists of less than 100 bytes and is counted by Android as outgoing traffic and will be visible in the speed graph notification as well.

(20) Can I Greenify/hibernate NetGuard?

No. Greenifying or otherwise hibernating NetGuard will result in rules not being applied when connectivity changes from Wi-Fi/mobile, screen on/off and roaming/not roaming.

(21) Does doze mode affect NetGuard?

I am not sure, because the doze mode documentation is not clear if the Android VPN service will be affected.

To be sure you can disable battery optimizations for NetGuard manually like this:

Android settings > Battery > three dot menu > Battery optimizations > Dropdown > All apps > NetGuard > Don't optimize > Done

This cannot be done from the application, because according to Google NetGuard is not an application type allowed to do this.

(22) Can I tether / use Wi-Fi calling while using NetGuard?

Yes, but this needs to be enabled in the settings. If it works depends on your Android version, because some Android versions have a bug preventing tethering and the VPN service to work together.

Some devices hibernate Wi-Fi preventing tethering to work when the screen is off. This behavior can be disabled in the Android enhanced/advanced Wi-Fi settings.

(24) Can you remove the notification from the status bar?

Android can kill background services at any time. This can only be prevented by turning a background service into a foreground service. Android requires an ongoing notification for all foreground services to make you aware of potential battery usage (see question 4). So, the notification cannot be removed without causing instability. However, the notification is being marked as low priority, which should result in moving it to the bottom of the list.

The key icon and/or the VPN running notification, which is shown by Android and not by NetGuard, can unfortunately not be removed. The Google documentation says: "A system-managed notification is shown during the lifetime of a VPN connection".

(25) Can you add a 'select all'?

There is no need for a select all function, because you can switch from black list to white list mode using the settings. See also question 0.

(27) How do I read the blocked traffic log?

The columns have the following meaning:

1. Time (tap on a log entry to see the date)
2. Application icon (tap on a log entry to see the application name)
3. Application UID
4. Wi-Fi / mobile connection, green=allowed, red=blocked
5. Interactive state (screen on or off)
6. Protocol (see below) and packet flags (see below)
7. Source and destination port (tap on a log entry to lookup a destination port)
8. Source and destination IPv4 or IPv6 address (tap on a log entry to lookup a destination IP address)
9. Organization name owning the IP address (need to be enabled through the menu)

Protocols:

• ICMP
• IGMP
• ESP (IPSec)
• TCP
• UDP
• Number = one of the protocols in this list
• 4 = IPv4
• 6 = IPv6

Packet flags:

• S = SYN
• A = ACK
• P = PSH
• F = FIN
• R = RST

For a detailed explanation see here.

(28) Why is Google connectivity services allowed internet access by default?

The Google connectivity services system application checks if the current network is really connected to the internet. This is probably done by briefly connecting to some Google server.

If this is not the case, there will be an '!' in the Wi-Fi or mobile icon in the system status bar.

Recent Android versions seem not to switch connectivity from mobile to Wi-Fi when the Wi-Fi network is not really connected, even though there is a connection to the Wi-Fi network (or the other way around). On Android 6.0 and later you might get a notification asking you if you want to keep this connection on or not. To prevent a bad user experience there is a predefined rule to default allow the Google connectivity services.

You can find all predefined rules here.

(29) Why do I get 'The item you requested is not available for purchase'?

You can only purchase pro feature when you installed NetGuard from the Play store.

(30) Can I also run AFWall+ on the same device?

Unless you are just testing NetGuard, there is no current reason to use them both, since they cover the same function (firewall), although with different base needs (AFWall+ needs a rooted device) and ways of doing their thing (AFWall+ uses iptables).

Also you need to keep per applicaton access rules always in sync, else the application will not be able to access the network, hence bringing another level of complexity when setting and assuring things work out.

Some pointers on how to set up AFWall+:

• if not using filtering in NetGuard, applications need direct internet access (Wi-Fi and/or mobile) in AFWall+
• if using filtering, NetGuard will need internet access (Wi-Fi and/or mobile) in AFWall+
• if using filtering, when you un/reinstall NetGuard, remember to RE-allow NetGuard in AFWall+
• if using filtering, applications need VPN internet access (check the box to show that option in AFWall+ settings)

(31) Why can some applications be configured as a group only?

For a lot of purposes, including network access, Android groups applications on UID and not on package/application name. Especially system applications often have the same UID, despite having a different package and application name, these are set up like this by the ROM manufacturer at build time. These applications can only be allowed/blocked access to the internet as a group.

(32) Why is the battery/network usage of NetGuard so high?

This is because Android contributes battery and network usage which is normally contributed to other applications to NetGuard in IP filtering mode. The total battery usage is slightly higher when IP filtering mode is enabled. IP filtering mode is always enabled on Android version before 5.0 and optionally enabled on later Android versions.

(33) Can you add profiles?

Profiles are inconvenient because they need to be operated manually. Conditions like 'When screen is on' are on the other hand convenient because they work automatic. Therefore profiles will not be added, but you are welcome to propose new conditions, however they need to be generally usable to be included.

As a workaround you can use the export/import function to apply specific settings in specific circumstances.

(34) Can you add the condition 'when on foreground'?

Recent Android versions do not allow an application to query if other applications are in the foreground or background anymore, so this cannot be added. You can use the condition 'when screen is on' instead.

(35) Why does the VPN not start?

NetGuard "asks" Android to start the local VPN service, but some Android versions contain a bug which prevents the VPN from starting (automatically). Sometimes this is caused by updating NetGuard. Unfortunately this cannot be fixed from NetGuard. What you can try is to restart your device and/or revoke the VPN permissions from NetGuard using the Android settings. Sometimes it helps to uninstall and install NetGuard again (be sure to export your settings first).

(36) Can you add PIN or password protection?

Since turning off the VPN service using the Android settings cannot be prevented, there is little use in adding PIN or password protection.

(37) Why are the pro features so expensive?

The right question is "why are there so many taxes and fees":

• VAT: 25% (depending on your country)
• Google fee: 30%
• Income tax: 50%

So, what is left for the developer is just a fraction of what you pay.

Despite NetGuard being really a lot of work, only some of the convenience and advanced features needs to be purchased, which means that NetGuard is basically free to use and that you don't need to pay anything to reduce your data usage, increase battery life and increase your privacy.

Also note that most free applications will appear not to be sustainable in the end, whereas NetGuard is properly maintained and supported, and that free applications may have a catch, like sending privacy sensitive information to the internet.

(38) Why did NetGuard stop running?

On most devices, NetGuard will keep running in the background with its foreground service. On some devices (in particular some Samsung models), where there are lots of applications competing for memory, Android may still stop NetGuard as a last resort. Unfortunately this cannot be fixed from NetGuard, and can be considered a shortcoming of the device and/or as a bug in Android.

(39) Which usage data will be shared?

On Android version 5.0 or newer, NetGuard will share anonymized usage data to help improve how NetGuard protects you, by understanding how end users work with NetGuard.

The following data will be shared when changing application settings:

• The SHA256 hashed Android ID (needed to prevent multiple records of the same setting)
• The device name *
• The Android version *
• The country configured when initializing Android *
• The application name, version and installer and whether an application is a user installed or a system bundled application
• Whether Wi-Fi and mobile connections will be blocked or allowed and which conditions apply (when screen on, roaming, notify on access, addresses, etc)

This data cannot be used to identify you, so your privacy is guaranteed. Data marked with an asterix (*) is being shared by Google in the Google Play developer console as well.

Usage data will be queued for sending over an unmetered connection (mostly Wi-Fi) when settings are being changed. Usage data will be anonynized before sending. Sending usage data can optionally be disabled per application.

You can see the aggregated data here.

If you didn't find the answer to your question, you can ask your questions in this forum or contact me directly by e-mail.

If you want to request a new feature or want to report a bug, please create an issue on GitHub.