Check if a VPN connection is active in Android?

问题:

I have a third party VPN app on my non-rooted Android 4.4 device, and want to write a background service to monitor the VPN connection and alert the user if the VPN connection has been broken.

Is there a way to do this? I couldn't find any way using the VPNService API.

Thanks -D

回答1:

This is works for me: Tested from API 16 to 23:

  List<String> networkList = new ArrayList<>();
    try {
        for (NetworkInterface networkInterface : Collections.list(NetworkInterface.getNetworkInterfaces())) {
            if (networkInterface.isUp())
                networkList.add(networkInterface.getName());
        }
    } catch (Exception ex) {
        Timber.d("isVpnUsing Network List didn't received");
    }

    return networkList.contains("tun0");

P.S. Also it can be another networkInterface with name "ppp0", but in my tests with different VPN apps it's always was "tun0"

回答2:

Using NetworkCapabilities worked for me. You have to loop over all existing networks and check which has VPN_TRANSPORT

ConnectivityManager cm = (ConnectivityManager)mContext.getSystemService(Context.CONNECTIVITY_SERVICE);
Network[] networks = cm.getAllNetworks();

Log.i(TAG, "Network count: " + networks.length);
for(int i = 0; i < networks.length; i++) {

  NetworkCapabilities caps = cm.getNetworkCapabilities(networks[i]);

  Log.i(TAG, "Network " + i + ": " + networks[i].toString());
  Log.i(TAG, "VPN transport is: " + caps.hasTransport(NetworkCapabilities.TRANSPORT_VPN));
  Log.i(TAG, "NOT_VPN capability is: " + caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN));

}

回答3:

Write a little app that hits an internal page or pings an internal site...

HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet(internal_url);
HttpResponse response = client.execute(request);

String html = "";
InputStream in = response.getEntity().getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
StringBuilder str = new StringBuilder();
String line = null;
while((line = reader.readLine()) != null)
{
    str.append(line);
}
in.close();
html = str.toString();

or

String str = "";
try 
{
    Process process = Runtime.getRuntime().exec(
            "/system/bin/ping -c 8 " + internal_url);
    BufferedReader reader = new BufferedReader(new InputStreamReader(
            process.getInputStream()));
    int i;
    char[] buffer = new char[4096];
    StringBuffer output = new StringBuffer();
    while ((i = reader.read(buffer)) > 0)
        output.append(buffer, 0, i);
    reader.close();


    str = output.toString();

} 
catch (IOException e)
{

    e.printStackTrace();
}
return str;

回答4:

How about checking the network infos? If one has a type of VPN, I would assume there's a VPN connection.

Requires the ACCESS_NETWORK_STATE permission.

            List<NetworkInfo> connectedNetworks    = new ArrayList<>();

        if (Build.VERSION.SDK_INT >= 21)
            {
            Network[] networks = m_ConnectivityManager.getAllNetworks();

            for (Network n : networks)
                {
                NetworkInfo ni = m_ConnectivityManager.getNetworkInfo(n);

                if (ni.isConnectedOrConnecting())
                    {
                    connectedNetworks.add(ni);
                    }
                }
            }
        else
            {
            NetworkInfo[] nis = m_ConnectivityManager.getAllNetworkInfo();

            for (NetworkInfo ni : nis)
                {
                if (ni.isConnectedOrConnecting())
                    {
                    connectedNetworks.add(ni);
                    }
                }
            }

        boolean bHasVPN = false;

        if (Build.VERSION.SDK_INT >= 21)
            {
            for (NetworkInfo ni : connectedNetworks)
                {
                bHasVPN |= (ni.getType() == ConnectivityManager.TYPE_VPN);
                }
            }