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I want to find the ip that my computer connects to the internet correctly.I have questions about a few things I have tried. Firstly : 

foreach(NetworkInterface ni in NetworkInterface.GetAllNetworkInterfaces()) {
    var addr = ni.GetIPProperties().GatewayAddresses.FirstOrDefault();
    if (addr != null && ni.OperationalStatus == OperationalStatus.Up) {
        switch (ni.NetworkInterfaceType) {
        case NetworkInterfaceType.Wireless80211:
        case NetworkInterfaceType.Ethernet:
            {
                foreach(UnicastIPAddressInformation ip in ni.GetIPProperties().UnicastAddresses) {
                    if (ip.Address.AddressFamily == AddressFamily.InterNetwork) {
                        return ip.Address.ToString();
                    }
                }

                break;
            }
        }
    }
}

When I tried the code above, if my computer has a virtual adapter installed (for example vpn), the vpn adapter is also detected as ethernet and operational status up. When I run vpn, there are two strings ip like (192.168.1.24 and 25.25.1.150). As a result of this error, I decided to find the name of my computer and ping it and find a rope with the returned result. like the code below: 

int timeout = 10000;
Ping ping = new Ping();
try {
    PingReply pingreply = ping.Send(Environment.MachineName.ToString(), timeout);
    if (pingreply.Status == IPStatus.Success) {
        return pingreply.Address.ToString();
    }
}
catch(Exception ex) {
    LogHelper.WriteErrorLog(ex);
    return String.Empty;
}
return String.Empty;

The code above works fine, but there are a few things I can't be sure of. Is there a possibility that the hostname with the second code will be return null? If there are two computer names in the same domain(can be possible?), can I get the correct result from the ping result? Is there any other way than these two codes find correctly under all circumstances? Thank you.

Heisenberg
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  • You might want to take a look at this question: https://stackoverflow.com/questions/2172962/how-to-determine-which-network-adapter-is-connected-to-the-internet – JonasH May 13 '20 at 13:41
  • When I examined and used "iphlpapi.dll", I found that it needed HostName again. So the answer to the question "If there are two computer names in the same domain(can be possible?), can I get the correct result from the ping result?" I asked about my question is not in this link. @JonasH also I already checked that link. – Heisenberg May 13 '20 at 13:51
  • The short answer is no. Pinging the computer is not a reliable way to get the network adapter that is connected to the internet since this will succeed even if not connected to the internet. As far as I know the only way is to check the route to some IP that is guaranteed to be on the internet. – JonasH May 13 '20 at 14:39
  • @JonasH When I disconnect my internet connection and ping it, I get no IPv4 connection by Exception. ..... – Heisenberg May 13 '20 at 14:44

0 Answers0