Add exception to ipfw firewall (fixes Vagrant+VirtualBox with Cisco VPN)

README.md

Should work for Vagrant managed VirtualBox virtual machines hosted on OS X (up to OS X Maverics which has ipfw-based firewall. OS X Yosemite has another pf-based firewall so not sure about that...)

Usage:

Run with sudo and pass in your VirtualBox managed VM's vboxnet IP address or address range:

sudo ruby add_ipfw_exception.rb 172.16.0.0/12

add_ipfw_exception.rb

#!ruby
if ENV['USER'] != 'root'
  puts "I need to run with sudo!"
  exit(1)
end

if ARGV[0].nil?
  puts "Please provide the ip address or ip range for the exception"
  exit(0)
end

deny_rule_string = 'deny ip from any to any'
deny_rule_id = nil

rules = `ipfw list`.split(/\n/)

rules.each do |rule|
  if rule.index(deny_rule_string)
    deny_rule_id = rule.split(/ /).first
    break
  end
end

if deny_rule_id.nil?
  puts "Bad rule was not found. Carry on."
  exit(0)
end

`ipfw add #{deny_rule_id.to_i - 1} allow ip from #{ARGV[0]} to any`
exit(0)