c# - .NET Core 2.x how to get the current active local network IPv4 address?

Question

On which is running the WebService. Like the one I can get in cmd.exe > ipconfig:

What I would like to achieve is automatic IP configuration of Kestrel, like:

.UseKestrel(opts => 
    { 
        opts.Listen(/*LocalIPv4ActiveAddress*/, 5000);
    }) 

So I can switch my development machines with different active network interfaces (WiFi || Ethernet) and different local network IP addresses.

Answer 1

You can try something like this:

// order interfaces by speed and filter out down and loopback
// take first of the remaining
var firstUpInterface = NetworkInterface.GetAllNetworkInterfaces()
    .OrderByDescending(c => c.Speed)
    .FirstOrDefault(c => c.NetworkInterfaceType != NetworkInterfaceType.Loopback && c.OperationalStatus == OperationalStatus.Up);
if (firstUpInterface != null) {
    var props = firstUpInterface.GetIPProperties();
    // get first IPV4 address assigned to this interface
    var firstIpV4Address = props.UnicastAddresses
        .Where(c => c.Address.AddressFamily == AddressFamily.InterNetwork)
        .Select(c => c.Address)
        .FirstOrDefault();
}