using System.Net.NetworkInformation;
using System.Net.Sockets;

foreach (NetworkInterface netif in NetworkInterface.GetAllNetworkInterfaces()
 .Where(a => a.SupportsMulticast)
 .Where(a => a.OperationalStatus == OperationalStatus.Up)
 .Where(a => a.NetworkInterfaceType != NetworkInterfaceType.Loopback)
 .Where(a => a.GetIPProperties().GetIPv4Properties() != null)
 .Where(a => a.GetIPProperties().UnicastAddresses.Any(ua => ua.Address.AddressFamily == AddressFamily.InterNetwork))
 .Where(a => a.GetIPProperties().UnicastAddresses.Any(ua => ua.IsDnsEligible))
)
{

 Console.WriteLine("Network Interface: {0}", netif.Name);
 IPInterfaceProperties properties = netif.GetIPProperties();
 foreach (IPAddressInformation unicast in properties.UnicastAddresses)
  Console.WriteLine("\tUniCast: {0}", unicast.Address);
}

string localIP;
using (Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, 0))
{
 socket.Connect("8.8.8.8", 65530);
 IPEndPoint endPoint = socket.LocalEndPoint as IPEndPoint;
 localIP = endPoint.Address.ToString();
}
Console.WriteLine(localIP);

using System.Net;

string sHostName = Dns.GetHostName();
IPHostEntry ipE = Dns.GetHostEntry(sHostName);
IPAddress[] IpA = ipE.AddressList;
for (int i = 0; i < IpA.Length; i++)
{
 Console.WriteLine("IP Address {0}: {1} ", i, IpA[i].ToString());
}