To Get Local Machine IP in C#

What is the syntax for getting the computer's own (if possible, external) IP address?
IPHostEntry host; string localIP = "?";
host = Dns.GetHostEntry(Dns.GetHostName()); foreach (IPAddress ip in host.AddressList) {
    if (ip.AddressFamily.ToString() == "InterNetwork")
    {
        localIP = ip.ToString();
    } } return localIP;