获取本机IP（考虑多块网卡、虚拟机等复杂情况）

方法1：

基本思路：

通过查询本机路由表，获取访问默认网关时使用的网卡IP地址。该方法在有网络的情况下适应性较好，如果本身不连接到互联网，则无法获取。

代码如下：

        /// <summary>
        /// 获取当前使用的IP
        /// </summary>
        /// <returns></returns>
        public static string GetLocalIP()
        {
            string result = RunApp("route", "print", true);
            Match m = Regex.Match(result, @"0.0.0.0\s+0.0.0.0\s+(\d+.\d+.\d+.\d+)\s+(\d+.\d+.\d+.\d+)");
            if (m.Success)
            {
                return m.Groups[2].Value;
            }
            else
            {
                try
                {
                    System.Net.Sockets.TcpClient c = new System.Net.Sockets.TcpClient();
                    c.Connect("www.baidu.com", 80);
                    string ip = ((System.Net.IPEndPoint)c.Client.LocalEndPoint).Address.ToString();
                    c.Close();
                    return ip;
                }
                catch (Exception)
                {
                    return null;
                }
            }
        }

        /// <summary>
        /// 获取本机主DNS
        /// </summary>
        /// <returns></returns>
        public static string GetPrimaryDNS()
        {
            string result = RunApp("nslookup", "", true);
            Match m = Regex.Match(result, @"\d+\.\d+\.\d+\.\d+");
            if (m.Success)
            {
                return m.Value;
            }
            else
            {
                return null;
            }
        }

        /// <summary>
        /// 运行一个控制台程序并返回其输出参数。
        /// </summary>
        /// <param name="filename">程序名</param>
        /// <param name="arguments">输入参数</param>
        /// <returns></returns>
        public static string RunApp(string filename, string arguments, bool recordLog)
        {
            try
            {
                if (recordLog)
                {
                    Trace.WriteLine(filename + " " + arguments);
                }
                Process proc = new Process();
                proc.StartInfo.FileName = filename;
                proc.StartInfo.CreateNoWindow = true;
                proc.StartInfo.Arguments = arguments;
                proc.StartInfo.RedirectStandardOutput = true;
                proc.StartInfo.UseShellExecute = false;
                proc.Start();

                using (System.IO.StreamReader sr = new System.IO.StreamReader(proc.StandardOutput.BaseStream, Encoding.Default))
                {
                    string txt = sr.ReadToEnd();
                    sr.Close();
                    if (recordLog)
                    {
                        Trace.WriteLine(txt);
                    }
                    if (!proc.HasExited)
                    {
                        proc.Kill();
                    }
                    return txt;
                }
            }
            catch (Exception ex)
            {
                Trace.WriteLine(ex);
                return ex.Message;
            }
        }