如果你在内部网络中运行，你将能够获得本地机器的IP地址，如果不是，你将获得外部IP地址: 网络:

//this will bring the IP for the current machine on browser
System.Web.HttpContext.Current.Request.UserHostAddress

桌面:

//This one will bring all local IPs for the desired namespace
IPAddress[] localIPs = Dns.GetHostAddresses(Dns.GetHostName());

另一种获取公共IP地址的方法是使用OpenDNS的resolve1.opendns.com服务器，并将myip.opendns.com作为请求。

在命令行上，这是:

  nslookup myip.opendns.com resolver1.opendns.com

或者在c#中使用DNSClient nuget:

  var lookup = new LookupClient(new IPAddress(new byte[] { 208, 67, 222, 222 }));
  var result = lookup.Query("myip.opendns.com", QueryType.ANY);

这比敲击http端点并解析响应要简洁一些。

了解你的公共IP的唯一方法是让别人告诉你;这段代码可以帮助你:

public string GetPublicIP()
{
    String direction = "";
    WebRequest request = WebRequest.Create("http://checkip.dyndns.org/");
    using (WebResponse response = request.GetResponse())
    using (StreamReader stream = new StreamReader(response.GetResponseStream()))
    {
        direction = stream.ReadToEnd();
    }

    //Search for the ip in the html
    int first = direction.IndexOf("Address: ") + 9;
    int last = direction.LastIndexOf("</body>");
    direction = direction.Substring(first, last - first);

    return direction;
}

为了找到IP地址列表，我已经使用了这个解决方案

public static IEnumerable<string> GetAddresses()
{
    var host = Dns.GetHostEntry(Dns.GetHostName());
    return (from ip in host.AddressList where ip.AddressFamily == AddressFamily.lo select ip.ToString()).ToList();
}

但我个人喜欢下面的解决方案，以获得本地有效的IP地址

public static IPAddress GetIPAddress(string hostName)
{
    Ping ping = new Ping();
    var replay = ping.Send(hostName);

    if (replay.Status == IPStatus.Success)
    {
        return replay.Address;
    }
    return null;
 }

public static void Main()
{
    Console.WriteLine("Local IP Address: " + GetIPAddress(Dns.GetHostName()));
    Console.WriteLine("Google IP:" + GetIPAddress("google.com");
    Console.ReadLine();
}

如果你想避免使用DNS:

List<IPAddress> ipList = new List<IPAddress>();
foreach (var netInterface in NetworkInterface.GetAllNetworkInterfaces())
{
    foreach (var address in netInterface.GetIPProperties().UnicastAddresses)
    {
        if (address.Address.AddressFamily == AddressFamily.InterNetwork)
        {
            Console.WriteLine("found IP " + address.Address.ToString());
            ipList.Add(address.Address);
        }
    }
}

private static string GetLocalIpAdresse()
    {
        var host = Dns.GetHostEntry(Dns.GetHostName());
        foreach(var ip in host.AddressList)
        {
            if (ip.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)
            {
                return ip.ToString();
            }
        }
        throw new Exception  ("No network adapters with an IPv4 address in the system");
    }