public string ResponseMyIP()
        {
                string str = null;
                //这个负责抓IP的页。第一步先抓取这个html页的全部内容
                string url = "http://www.ikaka.com/ip/index.asp";
                WebClient wc = new WebClient();
                wc.Credentials = CredentialCache.DefaultCredentials;
                Byte[] pageData = wc.DownloadData(url);
                string MyUrl = System.Text.Encoding.UTF8.GetString(pageData);
                //正则找到页面中的IP部分，并输出。
                Regex regex = new Regex(@"(((\d{1,2})|(1\d{2})|(2[0-4]\d)|(25[0-5]))\.){3}((\d{1,2})|(1\d{2})|(2[0-4]\d)|(25[0-5]))");
                foreach (Match m in regex.Matches(MyUrl))
                {
                    str = m.ToString();
                }
                return str;          
           
        }

string user_IP;
        if (System.Web.HttpContext.Current.Request.ServerVariables["HTTP_VIA"] != null)
        {
            user_IP = System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString();
        }
        else
        {
            user_IP = System.Web.HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"].ToString();
        }

------解决方案--------------------
C# code
string qip = "";
            if (Request.ServerVariables["HTTP_VIA"] != null)
            {
                qip = Request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString();
            }
            else
            {
                qip = Request.ServerVariables["ReMOTE_ADDR"].ToString();
            }

------解决方案--------------------
static string GetPage(string url) 
 { 
 HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url); 
 try 
 { 
 using (HttpWebResponse res = (HttpWebResponse)req.GetResponse()) 
 { 
 using (StreamReader sr = new StreamReader(res.GetResponseStream())) 
 { 
 return sr.ReadToEnd(); 
 } 
 } 
 } 
 catch (System.Exception e) 
 { 
 return e.Message; 
 } 
 finally 
 { 
 req.Abort(); 
 } 
 } 
 // 通过外部网站得到本机的外部IP 
 static string GetOuterIP() 
 { 
 string patt = @"IP: \[(? <IP>[0-9\.]*)\]"; 
 string url = ""; 
 return Regex.Match(GetPage(url), patt).Groups["IP"].Value; 
 } 

 static void Main() 
 { 
 foreach (IPAddress ip in Dns.GetHostEntry(Dns.GetHostName()).AddressList) 
 { 
 Console.WriteLine(ip); 
 } 
 Console.WriteLine(); 
 Console.WriteLine(GetOuterIP()); 
 }  
  


------解决方案--------------------
你是想获取他所在的位置吧?  
/// <summary>
       /// 获取指定URL页面的内容，使用HttpWebRequest方式
       /// </summary>
       /// <param name="xURL">URL的字符串表现形式</param>
       /// <param name="encode">页面使用的编码</param>
       /// <returns>返回页面HTML代码</returns>
       public string Get_Page(string xURL)
       {
           string content = "";
           HttpWebRequest httpget = (HttpWebRequest)HttpWebRequest.Create(xURL);
           try
           {
               HttpWebResponse httpres = (HttpWebResponse)httpget.GetResponse();
               Stream httpstr = httpres.GetResponseStream();
               StreamReader sr