Firewall and 2 eth interfaces


I have a question about AFP firewall.
In conf.afp if defined untrusted /firewalled/ network interface.
there is text: “Only one interface is accepted for each value”.
It means that my eth0 with publis IP is secured by AFP and eth1 with public IP os total open?

Thank you for unswer.

any answer?
is possible to config firewall for 2 ent interfaces?