[KLUG Members] Routing after validating IP address

[Komal]

Is there a way to configure Linux to forward packets only if the IP
address validates against a IP address-to MAC table?

I have several machines which have priviledges based on their IP
address
like higher bandwidth, outgoing SMTP, etc. Now it is entirely
possible,
that when any of these machines are down (typcally at the end of the
day or early morning), someone in the office can statically set their
IP address to any of these and enjoy these priviledges.

How do I validate IP addresses before routing? I know I can do this by
creating a userspace netfilter process which marks packets after
validation, but is there any out of the box solution?

Thanks

Regards,

Komal