Add AWS IP ranges to vpn config file.

aws_vpn_routes.rb

#!/usr/bin/env ruby

# This script outputs a series of lines that can be added to the [ipv4] section
# of a NetworkManager VPN config file (typically found in
# /etc/NetworkManager/system-connections/)
#
# ./aws_vpn_routes.rb | sudo tee -a /etc/NetworkManager/system-connections/<connection_name>

require 'net/http'
require 'json'

AWS_IPRANGES_ENDPOINT='https://ip-ranges.amazonaws.com/ip-ranges.json'

def get_ipranges_data
  resp = Net::HTTP.get_response(URI.parse(AWS_IPRANGES_ENDPOINT))
  unless resp.is_a?(Net::HTTPSuccess)
    abort "Error downloading ipranges data: #{resp.code} #{resp.message}\n#{resp.body}"
  end
  JSON.parse(resp.body)
end

get_ipranges_data.fetch("prefixes").each_with_index do |prefix, i|
  ip, masklen = prefix.fetch("ip_prefix").split('/', 2)
  puts "routes#{i+1}=#{ip};#{masklen};0.0.0.0;0;"
end