#!/usr/bin/env ruby

# Purpose
# Iterate over a range of IP addresses
# Change the /etc/network/interfaces subnet

# WARNING!
# I haven't tested this yet
# It might not work

require 'rubygems'
require 'net/ssh'

hosts = (2..254).map {|x| "172.16.31.#{x}"}
username = "your_username_here"
password = "your_password_here"
cmd = "sed -i -r -e '/netmask/ s/255.255.255.0/255.255.254.0/' /etc/network/interfaces"

hosts.each do |host|
  begin
    Net::SSH.start( host , username, :password => password, :timeout => 5) do |ssh|
      puts ssh.exec! cmd
    end
  rescue Timeout::Error
    puts "  Timed out"
    puts host
  rescue Errno::EHOSTUNREACH
    puts "  Host unreachable"
    puts host
  rescue Errno::ECONNREFUSED
    puts "  Connection refused"
    puts host
  rescue Net::SSH::AuthenticationFailed
    puts "  Authentication failure"
    puts host
  end
end