NAT: 1-1 mapping from 192.168.x.x to 10.168.x.x ?

Hi,

I have a machine on a 192.168.x.x network that I would like to
configure in such a way that it believes to be in 10.168.x.x.

In other words, if a packet comes in from, say, 192.168.3.4, I would
like it to be mangled as it was coming from 10.168.3.4.

In the same way, I would like outgoing packets for 10.168.x.x to be
mapped to 192.168.x.x.

I read the iptables manual and found out abount DNAT and SNAT, but it
seems what they do at most is mangle addresses into a pool of
addresses, is a round robin fashion. I don't need round robin. I need
a 1-1 mapping.

Anybody knows if this is doable ?

Thanks!
stefano

Stefano Masini wrote:
> Hi,
>
> I have a machine on a 192.168.x.x network that I would like to
> configure in such a way that it believes to be in 10.168.x.x.
>
> In other words, if a packet comes in from, say, 192.168.3.4, I would
> like it to be mangled as it was coming from 10.168.3.4.
>
> In the same way, I would like outgoing packets for 10.168.x.x to be
> mapped to 192.168.x.x.
>
> [snip]
>
> Anybody knows if this is doable ?

Specify a netmask on the --to address. The example in the netfilter HOWTO:

# iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -o eth1 \
-j SNAT --to 1.2.3.0/24

The example does SNAT based on outgoing source address, whereas you
probably want to do SNAT based on incoming source address and DNAT based
on incoming destination address (separate rules) in PREROUTING for
different interfaces.