> None of the legitimate uses of source routing have any need to pass through
> a box that has GATEWAY off.

I consider "traceroute -g intermediary destination" to be a ligitimate use
of source routing, even when the intermeidary is a non-routing host.

When GATEWAY is off, the box should not pass packets in one interface and
out another, but I think it could still pass LSRR and SSRR packets in one
interface and back out the same interface; there could be another option
to disable that too (for use in firewalls etc.). 

--apb (Alan Barrett)