Unicast packets to multiple destinations -only-

[Luigi Corsello <mlreader@lucomp.net>]

Hi all,

I got 3 IPs in one interface (ip addr add, not aliasing), and wanted to 
only allow unicast packets to any of them (and/or their subnet in one 
case, to allow broadcasts for the local net).
Aim: no broadcasts, no multicast, spoofing prevention?.

You can't have multiple -d in rules. My quick solution was 3 tables
(this is a sample):

iptables -N ta
iptables -N tb
iptables -N tc

iptables -A tc -d ! $ip3 -j DROP
iptables -A tb -d ! $ip2 -j tc
iptables -A ta -d ! $ip1 -j tb

iptables -A INPUT -j ta

It works, much junk stays out.  All services work.
 From the list point of view, is this insane(a) stupid(b) or clever(c)? 
and why?

Cheers,
/lc