IP地址段遍历

#region 搜索ftp服务器地址
        /// <summary>
        /// 搜索ftp服务器
        /// </summary>
        public void SearchFtpServer()
        {

var beginIp=""192.168.1.1;
var endIp=""192.168.1.251;
            var currentIp = IPAddress.Parse(beginIp);
            var endIp = IPAddress.Parse(endIp);

            var beginNum = GetIpNumber(currentIp);
            var endNum = GetIpNumber(endIp);

            for (long i = beginNum; i <= endNum; i++)
            {
              //TODO:根据ip地址做事
                currentIp = NextIP(currentIp);
            }
        }

        #region ip地址相关
        /// <summary>
        /// 将ip地址转换为数字表示
        /// </summary>
        /// <param name="ip"></param>
        /// <returns></returns>
        private long GetIpNumber(IPAddress ip)
        {
            var ipBytes = ip.ToString().Split(new char[] { '.' });
            var num = Convert.ToInt64(ipBytes[0]) * 256 * 256 * 256 +
                Convert.ToInt64(ipBytes[1]) * 256 * 256 +
                Convert.ToInt64(ipBytes[2]) * 256 +
                Convert.ToInt64(ipBytes[3]);
            return num;
        }

        /// <summary>
        /// 从一个IPAddress 获取它的下一个 IPAddress
        /// </summary>
        /// <param name="theIP"></param>
        /// <returns></returns>
        private IPAddress NextIP(IPAddress theIP)
        {
            byte[] ipBytes = theIP.GetAddressBytes();
            if (ipBytes[3] != 255)
            {
                ipBytes[3] += 1;
            }
            else if (ipBytes[2] != 255)
            {
                ipBytes[2] += 1;
                ipBytes[3] = 1;
            }
            else if (ipBytes[1] != 255)
            {
                ipBytes[1] += 1;
                ipBytes[2] = 1;
                ipBytes[3] = 1;
            }
            else if (ipBytes[0] != 255)
            {
                ipBytes[0] += 1;
                ipBytes[1] = 1;
                ipBytes[2] = 1;
                ipBytes[3] = 1;
            }
            IPAddress ip = new IPAddress(ipBytes);

            return ip;
        }
        #endregion