Set the NTP server of your android device

android-set-ntp-server.md

tags
Android Android Things

Set the NTP server of your android device

Just use this command to set a server address to automatically sync your device time. ( ͡° ͜ʖ ͡°)✧

$ adb shell settings put global ntp_server <new-ntp-server>

Background

I have a Raspberry Pi 3 with Android Things installed on it. But the time is never synchronized...

After googling it, I found this piece of code in NtpTrustedTime.java

public class NtpTrustedTime implements TrustedTime {
    ...
    public static synchronized NtpTrustedTime getInstance(Context context) {
        if (sSingleton == null) {
            final Resources res = context.getResources();
            final ContentResolver resolver = context.getContentResolver();
            final String defaultServer = res.getString(
                    com.android.internal.R.string.config_ntpServer);
            final long defaultTimeout = res.getInteger(
                    com.android.internal.R.integer.config_ntpTimeout);
            final String secureServer = Settings.Global.getString(
                    resolver, Settings.Global.NTP_SERVER);
            final long timeout = Settings.Global.getLong(
                    resolver, Settings.Global.NTP_TIMEOUT, defaultTimeout);
            final String server = secureServer != null ? secureServer : defaultServer;
            sSingleton = new NtpTrustedTime(server, timeout);
            sContext = context;
        }
        return sSingleton;
    }
}

It shows that android tring to get NTP server from:

1. Settings.Global.NTP_SERVER first

2. Then com.android.internal.R.string.config_ntpServer

And the NTP server of my Android Things is time.android.com, that's why it dose not work (I'm in China...).

---

Fortunately, it is easy to set settings via adb:

$ adb shell settings put global ntp_server asia.pool.ntp.org

# test
$ adb shell settings get global ntp_server 
> asia.pool.ntp.org

🎉 CHEERS

I have 3 NTP addresses.

$ adb shell settings list global | grep ntp
ntp_server=<NTP_Server_Address_1>
ntp_server_2=<NTP_Server_Address_2>
ntp_server_dhcpopt=<NTP_Server_Address_3>

If the first NTP server is unreachable, the device tries to connect to the first one, after which it connects to the next NTP server.
Now, the command adb shell settings get global ntp_server returns the first NTP server that is unreachable, it does not return the server to which it is connected.
Is there any adb command to know which NTP server it is connected to?

Thanks

adb shell settings get global --- instructs on getting that specific config only and it is the expected behavior
to see how ntp actually connects using the current configurations, you would need to see the sync in action

There are actually more ntp servers used on android. System uses time.android.com (defined normally by the global settings vars .. not 100% sure) while gps uses whatever is defined on gps.conf. For example i created magisk module to force gps to use pool.ntp.org or time.xtracloud.net.

Some things you can do:

• for eg. you can use 3c network monitor, but since ntp sync does not happen so often you will not be able to see it in real time easily
• you might need a script to watch for connections on port 123 and log them
• or you can use some burp packet listener to monitor traffic from phone on pc
• best bet is to use a vpn firewall like netguard which does the logging as long as traffic is routed through its local vpn. You will watch for system (pid 1000) or gps (pid 1021). in my attempts i could not force sync time, even rebooting or setting time to manual, as it remains cached somehow. but the sync normally happens at least once a day

running android 11. i think the behavior is different from phone to phone.

Are you at liberty of sharing the magisk module that you created that forces GPS to utilize 'pool.ntp.org' or 'time.xtracloud.net'?

I created a repo with it https://github.com/fusionneur/fusionGPS . The module itself is a port for compatibility with latest magisk (see references in readme). I used it in the last 4 months and observed an improved location locking than with the default gps.conf on my OnePlus 7T PRO. Let me know on how it works for you. Also I invite anyone to propose updated and improved optimizations in gps.conf

You sir, are a gentleman and a scholar.

time.windows.com is a good choice in China.

Thank you for this thread.

There is no existing ntp_server setting in LineageOS 20 but can easily be created just by pushing the "put global ntp_server domain" command through adb.

Setting is preserved between reboots and my router logs can confirm that NTP address changed from time.android.com to the chosen NTP server. GPS automatically connects to time.xtracloud.net (Cloudflare) in this ROM.

Failed to execute this command, my devices is android 12 colorOS, it seems no write permisson

➜ /Users/guaio >adb shell settings put global ntp_server ntp.aliyun.com

Exception occurred while executing 'put':
java.lang.SecurityException: Permission denial: writing to settings requires:android.permission.WRITE_SECURE_SETTINGS
	at com.android.providers.settings.SettingsProvider.enforceWritePermission(SettingsProvider.java:2640)
	at com.android.providers.settings.SettingsProvider.mutateGlobalSetting(SettingsProvider.java:1632)
	at com.android.providers.settings.SettingsProvider.insertGlobalSetting(SettingsProvider.java:1586)
	at com.android.providers.settings.SettingsProvider.call(SettingsProvider.java:588)
	at android.content.ContentProvider.call(ContentProvider.java:2473)
	at android.content.ContentProvider$Transport.call(ContentProvider.java:521)
	at com.android.providers.settings.SettingsService$MyShellCommand.putForUser(SettingsService.java:382)
	at com.android.providers.settings.SettingsService$MyShellCommand.onCommand(SettingsService.java:278)
	at com.android.modules.utils.BasicShellCommandHandler.exec(BasicShellCommandHandler.java:97)
	at android.os.ShellCommand.exec(ShellCommand.java:38)
	at com.android.providers.settings.SettingsService.onShellCommand(SettingsService.java:50)
	at android.os.Binder.shellCommand(Binder.java:970)
	at android.os.Binder.onTransact(Binder.java:854)
	at android.os.Binder.execTransactInternal(Binder.java:1226)
	at android.os.Binder.execTransact(Binder.java:1163)

Thanks for the information. I've tried several servers, cn.ntp.org.cn is the fastest one in China.

In my device if I first of all do adb shell settings get global ntp_server, it returns null.

For those trying to connect to your TV, I used adb connect 192.168.1.65:5555 to connect to my tv via LAN. Once you run that command you're gonna have to click Accept on the pop-up that is shown on your tv screen.
adb devices should show your TV as active, then you can run the commands above.