Routing issues

[Ivan Capan <capica@luthien.irb.hr>]

I have a following setup: Debian with iptables firewalling out several
computers with routable IP addresses. In order to get responses from the
net, I had to manually add routing table with 'route add -host' for each
computer.                          

routing table is like this:
host1.domain    *               255.255.255.255 UH    0      0        0 eth1
host2.domain    *               255.255.255.255 UH    0      0        0 eth1
host3.domain    *               255.255.255.255 UH    0      0        0 eth1
localnet        *               255.255.255.0   U     0      0        0 eth0
localnet        *               255.255.255.0   U     0      0        0 eth1
default         maingateway     0.0.0.0         UG    0      0 	      0 eth0 
        (eth0 is outgoing interface, eth1 is local)

The question is: This firewall is supposed to be built in front of two C
subnets (on a same cable, it's a feature of a CISCO ruter, don't ask me   
details:). 
What kind of routing table must be built? Is it OK to put route
add -net xxx.yyy.zz1.0 dev eth1
add -net xxx.yyy.zz2.0 dev eth1 ?

I have a small margin for errors, because there are servers on that subnets 
which must be up 0-24 so I rather ask here before doing some nasty things :)