Different configs for dual-homed interfaces?

[THOMPSOND @ ORVB . SAIC . COM]

  As part of a firewall configuration, I want to configure a UNIX system
with two ethernet ports: one to the wild and wooly outside and one to the
trusted folks on the inside.  I would like to offer no services on the
outside port but be rather liberal in services offered to the insiders.
(More generally, I would like to be able to offer different sets of 
services on each port.)

  However, I can find no way to configure inetd to do this.  There is no
interface argument on inetd, nor on any of the service deamons, nor on
ifconfig.  I realize that tcpwrapper might control this, but I would like
to block access earlier than that, plus some of the inside services I 
want to offer cannot be controlled by tcpwrapper.

  I am planning to put a router outside of my firewall machine, but 
want an additional barrier against failure of the router.

  I am using a Sun SPARCstation and Sun OS 4.1.3 for my research, but the 
results will be applied to other systems; so a UNIX-wide solution is 
preferrable, but an OS-specific one will still be helpful, as we might be 
able to obtain a specific machine for this use.

  Thanks in advance.

-Dave Thompson, SAIC