Two natd daemons

[Ash]

Alexandr Lookoshkoff wrote:
> Hello freebsd-questions,
> 
>   I have gateway with two external links and want to some users using
>   second link. How it can be done?
> 
>   Is it possible via two copyes of natd running?
> 

What you are asking involves making a routing decision based on the 
source IP (sometimes called Policy Based Routing or Source Based 
Routing, depending on the vendor). IP Routing decisions are typically 
based on the destination address, not the source. What you want is some 
mechanism that will make route decisions based on the source address 
(i.e. packets with a source address from network A get routed out of 
interface 1 to gateway 1, while packets from  Network B get routed out 
of interface 2 to gateway 2).

I haven't used ipfw/natd in years, so I honestly don't know if natd/ipfw 
will allow you to do what you want. However, I do know that Packet 
Filter (pf(4) ported over to FreeBSD from OpenBSD) will allow you to do 
this. Check out pf.conf(5)'s man page and do a search for "route-to". 
You might want to check out Peter N. M. Hansteen's "Firewalling with 
with OpenBSD's PF packet filter":

http://www.bgnett.no/~peter/pf/en/long-firewall.html

As well as the official user's guide:

ftp://ftp.openbsd.org/pub/OpenBSD/doc/pf-faq.txt


Good luck to you,
-Ash