gateway/routing questions

[Chad Leigh -- Shire.Net LLC]

I used to have a situation like this but it was a few years ago and I 
have forgotten how to set this up in detail.

I have a class C network (public) and I have a FreeBSD box with lots of 
aliases on it providing various services.  There is also a Mandrake 
Linux box that belongs to a customer sitting on my net as well.  My 
provider where I am colocated provides the gateway for my class C in 
his fancy shmancy switch :-) .

I want to add another box (a Linux one unfortunately for some high 
performance Java 1.4 stuff that won't run on FreeBSD) but I want to 
make it so that it is on a private class C that should co-exist with my 
regular class C.

Lets say my public one is (this is made up) 128.1.1.0.  This is where 
the FBSD box lives.  I want to overlay 192.168.1.0 on my LAN.  I will 
give my FBSD box the address (alias) of 192.168.1.1 .  The new Linux 
box will have a bunch of addresses starting at 192.168.1.10 .

The Linux box on the 192.168 network should not have any access going 
out (so I don't need NAT for example) nor of course coming in.  But the 
FBSD box should continue to have its normal public access on 128.1.1.0 
network plus access the Linux box on 192.168.  The Linux box should be 
able to talk to the FBSD box.

I think that all I need to do is add an alias address (and a static 
route out the ethernet port?) to my BSD box and it should work.   I 
don't need anything else to have the BSD box live in this private 
network as well as the public one, since the private network does not 
need to get out at all.

Is this reasoning correct?  In my test lab here I cannot recreate this 
exactly given some restrictions on how it is set up and so when I go 
and take the Linux box and stick it in the data room on Friday it  
needs to work without lots of trouble :-)

thanks
Chad