# mac changer

case ARGV.length
    when 2
        interface = ARGV.shift # first argument is the interface ( usually eth0 )
        mac = ARGV.shift # mac address
    else
        puts "usage:change.rb <interface> <mac address>"
        raise SystemExit # we exit the script since we didn't receive proper arguments
end

if(mac !~ /(?:[0-9a-f][0-9a-f][-:]){5}[0-9a-f][0-9a-f]/i) # check for a valid mac ( or a potentially evil command :)    )
        puts "#{mac} is an invalid mac"
        raise SystemExit
end

case RUBY_PLATFORM
    when /linux/i        # if we're running under linux
        
        if(Process.uid != 0) # we should be root
            puts "script must be ran as root"
            raise SystemExit
        end

        # i didn't want to rely on the presence of which binary , so we search the path for ifconfig's location
        path    = ENV["PATH"]
        paths   = path.split(/:/)
        ifconf    = ""

        paths.each do |path|
            Dir.chdir(path) do
                if(File.exists?("ifconfig"))
                    puts "found ifconfig in #{path}"
                    ifconf = path +"/ifconfig" # if we found ifconfig
                end
            end
        end

        if(ifconf != "")    # if we know ifconfig's location
            system(ifconf + " #{interface} down");
            system(ifconf + " #{interface} hw ether " + mac)
            system(ifconf + " #{interface} up")
            puts "changed mac!"
        else  # ifconfig not found , adjust your path
            puts "ifconfig not found!"
            raise SystemExit
        end
    
    else
        puts "#{RUBY_PLATFORM} - unsupported platform!" # not running under linux
end