count_ec2_ips.rb - https://docs.aws.amazon.com/general/latest/gr/aws-ip-ranges.html

count_ec2_ips.rb

#!/usr/bin/env ruby

if %w(-h --help).include?(ARGV.first)
  abort <<~USAGE
    #{__FILE__} <FILE> to count IPs in given file
    #{__FILE__}        to count IPs using latest file on disk
    DL=1 #{__FILE__}   to download the AWS IP ranges
  USAGE
end

require "ipaddr"
require "json"
require "net/http"

ip_ranges_url = "https://ip-ranges.amazonaws.com/ip-ranges.json"
filename = ARGV.first

if ENV.key?("DL")
  date = Time.now.strftime("%F")
  filename = "ip-ranges_#{date}.json"
  ip_ranges_data = Net::HTTP.get(URI(ip_ranges_url))
  puts "✅  Downloaded #{ip_ranges_url}"
  File.write(filename, ip_ranges_data)
  puts "💾  Saved them to #{filename}"
else
  filename = Dir["ip-ranges_*.json"].reverse.first
end

no_file = filename.nil? || !File.exist?(filename)

abort "Run with DL=1 to download #{ip_ranges_url}" if no_file

puts "✏️   Counting IPs in #{filename}"

ip_ranges_data ||= File.read(filename)
ip_ranges = JSON.parse(ip_ranges_data)
count_v4  = ip_ranges["prefixes"]
  .select { |pref| pref["service"] == "EC2" }
  .map { |pref| 2 ** (32 - IPAddr.new(pref["ip_prefix"]).prefix) }
  .sum
count_v6 = ip_ranges["ipv6_prefixes"]
  .select { |pref| pref["service"] == "EC2" }
  .map { |pref| 2 ** (128 - IPAddr.new(pref["ipv6_prefix"]).prefix) / 2**(128-64) }.sum

puts "IPv4: #{count_v4}"
puts "IPv6: #{count_v6}"

✅  Downloaded https://ip-ranges.amazonaws.com/ip-ranges.json
💾  Saved them to ip-ranges_2025-02-04.json
✏️   Counting IPs in ip-ranges_2025-02-04.json
IPv4: 64920861
IPv6: 65532946485