C# - Prüfen ob Internet verfügbar ist.

// using System.Runtime.InteropServices;

[DllImport("WININET", CharSet = CharSet.Auto)]
static extern bool InternetGetConnectedState( out InternetConnectionState lpdwFlags, int dwReserved);

[Flags]
enum InternetConnectionState : int
{
    INTERNET_CONNECTION_MODEM = 0x1,
    INTERNET_CONNECTION_LAN = 0x2,
    INTERNET_CONNECTION_PROXY = 0x4,
    INTERNET_RAS_INSTALLED = 0x10,
    INTERNET_CONNECTION_OFFLINE = 0x20,
    INTERNET_CONNECTION_CONFIGURED = 0x40
}

// Beispielaufruf
InternetConnectionState flags;
bool Internetavaliable = InternetGetConnectedState(out flags, 0);