I hope the RFC1918 check is already made. If not it could be added. As I wrote before, there have been reasonable checks in place but people here have asked them to be removed because they wanted to do what the checks prevented. (like setting up a gateway with external address in net-44)
Rob
The default gateway entry behavior should as idiot proofed as possible I.e. Not letting one entry a 44 IP as a gateway address, and not letting you add subnets you aren't associated with.
I think somewhere less obvious (like under ones user profile) there should be a place to check a box to enable "advanced user options." And if that is checked then such abnormal things would be accepted?
Not sure how feasible/easy that sort of thing is for Chris to code though.
Those are my thoughts.