Yes it can you'll need to reconfigure the kernel to turn off ALL ip
forwarding if you want a firewall based on application layer proxying.

I can't rememeber if anyone has posted tips on how to carry out
transparant proxying.

Also there are few gotchas to look out for with such things a procfs,
not the best of examples as should strip out all unecessary features
from the kernel and the binary installation anyway.

I'd advice that you subscribe to the netbsd-security list for more
advice with such issues.

On Thu, 26 Mar 1998, John Maier wrote:

> I know NetBSD can function as a gateway but can it function as a Firewall?
> 
> I thought I saw a question on this subject 2-3 years ago, but I lost all of my old mail.
> 
> jam
>