If you are running release 0.3 or 0.4 of SUN UNIX ( 4.1c BSD ) and you wish to alter the point at which ARP takes over here is the patch : adb -w vmunix.new arpresolve + 0da ? ia should yield cmpl instruction if not quit. arpresolve + 0de ? x should yield 400 ( i.e. 1024) to zap it say ?w number ^D