determine Ethernet Adapter Local Area Connection IPv4 Address from Multiple IP Addresses returned

Question

I am using the below code to retrieve IPv4 Address (Ethernet Adapter Local Area Connection). But i see multiple addresses being returned by the code. Is there a way to say which of the returned addresses would be Ethernet Adapter Local Area Connection IP Address ?

    List<string> all = new List<string>();
    string hostName = Dns.GetHostName();
    IPHostEntry hostEntry = Dns.GetHostEntry(hostName);
    foreach (IPAddress address in hostEntry.AddressList)
    {
        if (address.AddressFamily == AddressFamily.InterNetwork)
            all.Add(address.ToString() + "\n");
    }

    dataGridView2.DataSource = all.Select(x => new { Value = x }).ToList();
}

currently the above code returns 3 values

• 172.20. * ** . ***
• 192.168. * ** . * **
• 192.168. * ** . * **

Ethernet Adapter Local Area Connection IP Address is 172.20. * ** . ***

Answer 1

Are you maybe looking for a connection of properties NetworkInterfaceType and AddressFamily?

foreach (var i in NetworkInterface.GetAllNetworkInterfaces())
{
   Console.WriteLine("{0} ({1})", i.Name, i.NetworkInterfaceType);
   foreach (var a in i.GetIPProperties().UnicastAddresses)
   {
      Console.WriteLine("      {0} ({1})", a.Address, a.Address.AddressFamily);
   }
}

this will give you for example:

Local Area Connection (Ethernet) (InterNetworkV6) 169.254.171.253 (InterNetwork)

Answer 2

Assuming only one connection of interest with one IPv4 address, consider something like this:

var connectionName = "Ethernet Adapter Local Area Connection";
var connection =
    NetworkInterface.GetAllNetworkInterfaces().FirstOrDefault(
        ni => ni.Name == connectionName);
if (connection != null)
{
    Console.WriteLine("Connection \"{0}\" found.", connectionName);

    // Use a regex to focus on the IPv4 address and ignore the IPv6 address if
    // present.
    var ipV4Regex = new Regex("(?<IPv4Address>([0-9]{1,3}\\.){3}[0-9]{1,3})");
    var unicastAddresses = connection.GetIPProperties().UnicastAddresses;
    var ipV4Address =
        unicastAddresses.FirstOrDefault(
            ua => ipV4Regex.Match(ua.Address.ToString()).Success);

    if (ipV4Address != null)
        Console.WriteLine("IPv4 address {0} found.", ipV4Address.Address);
    else
        Console.WriteLine("IPv4 address not found.");
}
else
{
    Console.WriteLine("Connection \"{0}\" not found.", connectionName);
}

I used console output for clarity, but you should find this adaptable to assigning dataGridView2.DataSource .

Answer 3

    {
        var sb = new StringBuilder();

        NetworkInterface[] networkInterfaces =
            NetworkInterface.GetAllNetworkInterfaces();

        foreach (NetworkInterface network in networkInterfaces)
        {
            IPInterfaceProperties properties = network.GetIPProperties();
            foreach (UnicastIPAddressInformation address in
                properties.UnicastAddresses)
            {
                if (address.Address.AddressFamily != AddressFamily.InterNetwork)  // We're only interested in IPv4 addresses for now 
                    continue;
                if (IPAddress.IsLoopback(address.Address))  // Ignore loopback addresses (e.g., 127.0.0.1) 
                    continue;
                if (network.OperationalStatus == OperationalStatus.Up)
                    sb.AppendLine(address.Address.ToString() + " (" + network.Name + ")");
            }
        }
        Console.WriteLine(sb.ToString());
    }