Enumerates IPv4 address space allocation.

ipv4.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
 
class Program
{
    static void Main()
    {
        var sources = new[] {
 
            // ARIN (American Registry for Internet Numbers)
            "ftp://ftp.arin.net/pub/stats/arin/delegated-arin-latest",
 
            // LACNIC (Latin American and Caribbean Internet Addresses Registry)
            "ftp://ftp.lacnic.net/pub/stats/lacnic/delegated-lacnic-latest",
 
            // APNIC (Asia-Pacific Network Information Centre)
            "http://ftp.apnic.net/stats/apnic/delegated-apnic-latest",
 
            // RIPE (Réseaux IP Européens)
            "ftp://ftp.ripe.net/ripe/stats/delegated-ripencc-latest",
 
            // AfriNIC
            "ftp://ftp.afrinic.net/pub/stats/afrinic/delegated-afrinic-latest" };
 
        var records = new[] { new { Country = "", Start = IPAddress.None, Length = 0 } }.ToList();
        records.Clear();
 
        foreach (var source in sources)
        {
            WebClient request = new WebClient();
            byte[] buffer = request.DownloadData(source);
            MemoryStream mem = new MemoryStream(buffer);
            StreamReader sr = new StreamReader(mem, Encoding.ASCII);
 
        Next:
            var line = sr.ReadLine();
            if (line == null) continue;
 
            if (line == "" || line[0] == '#') goto Next;
            var data = line.Split('|');
            if (data[2] == "ipv4" && data[5] != "summary")
                records.Add(new {
                    Country = data[1],
                    Start = IPAddress.Parse(data[3]),
                    Length = int.Parse(data[4]) });
            goto Next;
        }
 
        foreach (var record in (from rec in records
                                orderby IPtoLong(rec.Start)
                                select rec))
            Console.WriteLine(record.Country + "\t" + record.Start + "\t" + record.Length);
    }
 
    static long IPtoLong(IPAddress addr)
    {
        var bytes = addr.GetAddressBytes();
        return ((long)bytes[0] << 24) | ((long)bytes[1] << 16) | ((long)bytes[2] << 8) | (long)bytes[3];
    }
}