在项目中经常要获取用户的上网的IP地址，如何获取用户的IP地址，方法很多，现在介绍以下2种。

/// <summary>
        /// 获取本机在局域网的IP地址
        /// </summary>
        /// <returns></returns>
        private string GetLocalIPAddress()
        {
            System.Net.IPAddress[] addressList = Dns.GetHostEntry(Dns.GetHostName()).AddressList;
            string strNativeIP = "";
            string strServerIP = "";
            if (addressList.Length > 1)
            {
                strNativeIP = addressList[0].ToString();
                strServerIP = addressList[1].ToString();
            }
            else if(addressList.Length==1)
            {
                strServerIP = addressList[0].ToString();
            }
            return strServerIP;
        }

另外一种就是抓取网页中查询到的上网地址的IP来实现的。实现如下：

/// <summary>
        /// 获取本机的上网IP
        /// </summary>
        /// <returns></returns>
        private string GetConnectNetAddress()
        {
            string strUrl = "http://www.ip138.com/ip2city.asp"; //获得IP的网址
            Uri uri = new Uri(strUrl);
            WebRequest webreq = WebRequest.Create(uri);
            Stream s = webreq.GetResponse().GetResponseStream();
            StreamReader sr = new StreamReader(s, Encoding.Default);
            string all = sr.ReadToEnd(); //读取网站返回的数据 格式：您的IP地址是：[x.x.x.x]
            int i = all.IndexOf("[") + 1;
            string tempip = all.Substring(i, 15);
            string ip = tempip.Replace("]", "").Replace(" ", "").Replace("<", "");
            return ip;
        }