To select all active local IP addresses (v4), use the following C# code:
using System.Net;
using System.Net.NetworkInformation;
using System.Net.Sockets;
// …
private static IEnumerable<IPAddress> GetLocalV4Addresses()
{
return from iface in NetworkInterface.GetAllNetworkInterfaces()
where iface.OperationalStatus == OperationalStatus.Up
from address in iface.GetIPProperties().UnicastAddresses
where address.Address.AddressFamily == AddressFamily.InterNetwork
select address.Address;
}

