Android some network job(ping) doesn't work

Question

I am developing an android application. It uses some network service like:

• Firebase Firestore
• 3rd party REST API
• Ping.

When I develop this, everything works fine. So I tested it on my phone, and I uploaded it in the play store. After uploaded to the play store, I tried to download and tested. But ping is only failed!!!

I cannot understand this situation.

First, Firebase Firestore works fine.

Second, I am using 3rd party REST API. To using the service, I am using "Retrofit" library. It works fine too.

Third, my app has the feature to check server status. For this feature, I implemented "ping". This is just ping.

"ping -c 1 xxx.xxx.xxx.xxx"

And show the latency to the end user. It works fine in debug/release/signed APK.

But it doesn't work when I download from the play store.

I just added only one permission.

<uses-permission android:name="android.permission.INTERNET" />

Should I define ACCESS_NETWORK_STATE permission too? But Firestore and other 3rd party REST API works fine.

---

Below is my 'build.gradle' file.

android {
    signingConfigs {
        config {
            keyAlias xxx
            keyPassword xxx
            storeFile xxx
            storePassword 'xxx'
        }
    }
    compileSdkVersion 25
    buildToolsVersion "25.0.3"
    defaultConfig {
        multiDexEnabled true
        applicationId "xxx"
        minSdkVersion 22
        targetSdkVersion 25
        versionCode 16
        versionName "1.1.7"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            signingConfig signingConfigs.config
        }
        debug {
        }
    }
    productFlavors {
    }
}

And my "proguard-rules.pro" file is empty.

Below is my code to get the ping information.

    public static String ping(String host) throws IOException, InterruptedException {

    Runtime runtime = Runtime.getRuntime();
    Process proc = runtime.exec("ping -c 1 -w 3 " + host);
    proc.waitFor();
    int exit = proc.exitValue();

    if (exit == 0) {
        StringBuffer echo = new StringBuffer();
        try (BufferedReader buffer = new BufferedReader(new InputStreamReader(proc.getInputStream()))) {
            String line = "";
            while ((line = buffer.readLine()) != null) {
                echo.append(line + "\n");
            }
        }

        return getPingStats(echo.toString());
    } else if (exit == 1) {
        pingError = "failed, exit = 1";
        Log.e(TAG, "[CHICKEN] ping - error: " + pingError);
        return null;
    } else {
        pingError = "error, exit = 2";
        Log.e(TAG, "[CHICKEN] ping - error: " + pingError);
        return null;
    }
}