C#获取内外网IP地址

记录有效获取IP的方法

外网IP：

 public static string GetIPAddress()
        {
            string ip = "0.0.0.0";
            try
            {
                WebClient MyWebClient = new WebClient();
                MyWebClient.Credentials = CredentialCache.DefaultCredentials;//获取或设置用于向Internet资源的请求进行身份验证的网络凭据

                Byte[] pageData = MyWebClient.DownloadData("http://www.net.cn/static/customercare/yourip.asp"); //从指定网站下载数据

                string pageHtml = Encoding.Default.GetString(pageData);  //如果获取网站页面采用的是GB2312，则使用这句

                int i1 = pageHtml.IndexOf("<h2>"), i2 = pageHtml.IndexOf("</h2>");
                ip = pageHtml.Substring(i1 + 1, i2 - 1 - i1);
                ip = ip.Substring(3, ip.Length-3);
            }
            catch (WebException webEx)
            {
                webEx.Message.ToString();
            }
            return ip;
        }

　　内网IP：

//内网ip
        public static string GetLocalIP()
        {
            try
            {
                string HostName = Dns.GetHostName(); //得到主机名
                IPHostEntry IpEntry = Dns.GetHostEntry(HostName);
                for (int i = 0; i < IpEntry.AddressList.Length; i++)
                {
                    //从IP地址列表中筛选出IPv4类型的IP地址
                    //AddressFamily.InterNetwork表示此IP为IPv4,
                    //AddressFamily.InterNetworkV6表示此地址为IPv6类型
                    if (IpEntry.AddressList[i].AddressFamily == AddressFamily.InterNetwork)
                    {
                        return IpEntry.AddressList[i].ToString();
                    }
                }
                return "";
            }
            catch (Exception ex)
            {
                return "";
            }
        }

        //获取ip
        public static string GetIP()
        {
            string result = String.Empty;
            if (HttpContext.Current != null && HttpContext.Current.Session != null && HttpContext.Current.Session["IP"] != null)
            {
                result = HttpContext.Current.Session["IP"].ToString();
            }
            else
            {
                result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
                if (null == result || result == String.Empty)
                {
                    result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
                }

                if (null == result || result == String.Empty)
                {
                    result = HttpContext.Current.Request.UserHostAddress;
                }

                if (null == result || result == String.Empty || !IsIP(result))
                {
                    return "0.0.0.0";
                }
            }
            return result;
        }

　　验证字符串是否为IP：

1  public static bool IsIP(string ip)
2         {
3             return Regex.IsMatch(ip, @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$");
4         }