C#获取局域网中的所有正在使用的IP地址

方法不是很好。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Text.RegularExpressions;

namespace _12获取局域网中的所有IP地址
{
    class Program
    {
        static void Main(string[] args)
        {

            IPAddress startIP = InputIPAddress("请输入开始IP地址：");
            IPAddress endIP = InputIPAddress("请输入结束IP地址：");

            int startNum;
            int endNum;
            string str1;
            string str2;
            GetBound(startIP, out startNum, out str1);
            GetBound(endIP, out endNum, out str2);

            if (str1 != str2) 
            {
                Console.WriteLine("输入的IP不在同一段。");
                return;
            }
            for (int i = startNum; i < endNum; i++) 
            {
                try
                {
                    IPAddress ip = IPAddress.Parse(str1 + i);
                    Console.Write("[{0}] - [", ip);
                    IPHostEntry hostEntry = Dns.GetHostEntry(ip);
                    Console.WriteLine("{0}]", hostEntry.HostName);
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.Message + "]");
                }
            }

            Console.ReadKey();
        }

        static void Scan(IPAddress startIP, IPAddress endIP) 
        {

        }

        static void GetBound(IPAddress ip, out int num, out string str) 
        {
            string reg = @"(?<str>\d+\.\d+\.\d+\.)(?<num>\d+)";
            Match match = new Regex(reg).Match(ip.ToString());
            string numStr = match.Groups["num"].Value;
            num = Convert.ToInt32(numStr);
            str = match.Groups["str"].Value;
        }

        static IPAddress InputIPAddress(string msg) 
        {
            string msgTemp = msg;
            IPAddress ip = null;
            while (true) 
            {
                Console.Clear();
                Console.WriteLine(msg);
                string ipStr = Console.ReadLine();
                if (IPAddress.TryParse(ipStr, out ip))
                {
                    break;
                }
                else 
                {
                    msg = "输入的\"" + ipStr + "\"格式不正确，" + msgTemp;
                }
            }
            Console.Clear();

            return ip;
        }
    }
}