Delay in getting public IP from my asp.net application

Question

I have an asp.net website in which I am getting the external IP using the below code.

        public static string GetExternalIp()
        {
            try
            {
                string externalIP = "";
                externalIP = (webclient.DownloadString("http://checkip.dyndns.org/"));
                externalIP = (new Regex(@"\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}")).Matches(externalIP)[0].ToString();
                return externalIP;
            }
            catch {
                //return null;
                return Dns.GetHostByName(Environment.MachineName).AddressList[0].ToString();
            }
        }

The code is getting the external IP perfectly however, it takes 3 to 5 secs to get the public IP to my application. Based on this stackoverflow post Public IP Address i added the below line to my code as the user has mentioned this will be faster for the consecutive times in getting the public IP

public static WebClient webclient = new WebClient();

However this is also taking time. I googled and found another code using HTTPWebRequest. Below is the code

    string myExternalIP;
    string strHostName = System.Net.Dns.GetHostName();
    string clientIPAddress = System.Net.Dns.GetHostAddresses(strHostName).GetValue(0).ToString();
    string clientip = clientIPAddress.ToString();
    System.Net.HttpWebRequest request =
      (System.Net.HttpWebRequest) System.Net.HttpWebRequest.Create("http://www.whatismyip.org");
    request.UserAgent = "User-Agent: Mozilla/4.0 (compatible; MSIE" +
      "6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";
    System.Net.HttpWebResponse response =
      (System.Net.HttpWebResponse) request.GetResponse();
    using(System.IO.StreamReader reader = new StreamReader(response.GetResponseStream())) {
      myExternalIP = reader.ReadToEnd();
      reader.Close();
    }

This code is fast but its creating a html document containing the public IP.

How to get only the IP address from that HTML document?

Is there any code which will be more fast than the one I am currently using.

Where exactly are you stuck? If it takes time for an external service to respond, you can't control that. There's no code you can write which will speed up the internet. For the code at the end, why don't you simply parse the IP from the response? (Similarly to how you *already do* in the original code, though you'd need a much more complicated regular expression and, honestly, a DOM parser would make more sense at that point.) — David, Jan 15 '16 at 17:17
They both return an HTML document, in the first example you are parsing it out with a regular expression, why didn't you do that in the second? — CodingGorilla, Jan 15 '16 at 17:19

score 2 · Accepted Answer · answered Jan 15 '16 at 18:13

Use a different service, such as ipify.org with json response. It's faster and requires no parsing.

using Newtonsoft.Json;
using System.Net;

namespace Stackoverflow
{

    public static class GetExternalIP
    {
        class IpAddress
        {
            public string ip { get; set; }
        }
        public static string GetExternalIp()
        {

            WebClient client = new WebClient();

            string jsonData = client.DownloadString("https://api.ipify.org/?format=json");
            IpAddress results = JsonConvert.DeserializeObject<IpAddress>(jsonData);

            string externalIp = results.ip;

            return externalIp;
        }
    }
}

Delay in getting public IP from my asp.net application

1 Answers1