RunOnIpChange

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Threading;

namespace RunOnIpChange
{
    class Program
    {
        static void Main(string[] args)
        {
            string myLastIp = GetMyIp();
            while (true)
            {
                Thread.Sleep(15000);
                string myNewIp = GetMyIp();
                if (myNewIp != myLastIp)
                {
                    Console.Write(string.Format("{0}: new IP: {1}", DateTime.Now, myNewIp));
                    myLastIp = myNewIp;
                    DoStuff();
                }
                else
                {
                    Console.Write(string.Format("{0}: IP is still the same: {1}", DateTime.Now, myNewIp));
                }
            }
        }

        private static void DoStuff()
        {
        }

        private static string GetMyIp()
        {
            WebClient wc = new WebClient();
            return wc.DownloadString("http://myexternalip.com/raw");
        }
    }
}