ruby script to search a CIDR for a computer you can log into

find_lost_computer.rb

#!/usr/bin/env ruby

require 'netaddr'
require 'open3'
require 'parallel'
require 'io/console'
require 'net/ssh'

if ARGV.length != 1
  puts 'Pass search CIDR as the only argument'
  exit 1
end
cidr = ARGV.pop

print "Enter Username (#{ENV['USER']}): "
username = gets.strip
username = ENV['USER'] if username.length == 0

password = IO::console.getpass "Enter Password, leave blank for public key auth: "

addresses = NetAddr::IPv4Net.parse(cidr)
address_range = 0..(addresses.len - 1)

Parallel.each(address_range, in_threads: 20) do |address_index|
  address = addresses.nth(address_index).to_s
  options = {
    timeout: 1,
    verify_host_key: :never,
  }
  if password.length == 0
    options[:auth_methods] = ['publickey']
  else
    options[:auth_methods] = ['password']
    options[:password] = password
    options[:number_of_password_prompts] = 0
  end

  begin
    Net::SSH.start(address, username, options) do |ssh|
      output = ssh.exec!("hostname")
      puts "#{address}: #{output}"
    end
  rescue Net::SSH::ConnectionTimeout, Net::SSH::AuthenticationFailed, Errno::ECONNREFUSED, Errno::EACCES
  end
end