startup.lua

rednet.open('back')
print('Authorization Required')
while true do
    a, b = rednet.receive()
    if b == 'Cowabunga' then
        rs.setOutput('left', true)
        sleep(5)
        rs.setOutput('left', false)

    else
        rs.setOutput('left', false)

    end
    sleep(1)
end