using System;

using System.Collections.Generic;

using System.Net;

​

public class Program

{

    public static List<IPAddress> GenerateIPAddressList(string fromIP, string toIp)

    {

        var start = IPAddress.Parse(fromIP).GetAddressBytes();

        var end = IPAddress.Parse(toIp).GetAddressBytes();

        var addresses = new List<IPAddress>();

        for (var i = start[0]; i <= end[0]; i++)

            for (var j = start[1]; j <= end[1]; j++)

                for (var k = start[2]; k <= end[2]; k++)

                    for (var l = start[2]; l <= end[3]; l++)

                        addresses.Add(new IPAddress(new[]{i, j, k, l}));

        return addresses;

    }

​

    public static void Main()

    {

        var list = GenerateIPAddressList("192.168.1.1", "192.168.1.5");

        foreach (var ip in list)

        {

            Console.WriteLine(ip);

        }

    }

}