NAT possible with single interface box?

Rick van der Zwet info at
Mon Mar 12 13:27:52 UTC 2018


Could NAT translation be done with a single interface system without the 
use of VLANs?

I have ,a rather odd, (simplified) network configuration:
   - single interface system (Router) which has two private IP addresses and
   - The gateway (to the internet) is found at
   - The Client with IP
The Client (cannot be modified) is supposed to connect to the internet 
via the Router.

My pf rules on Router are:
   nat on sis0 inet proto tcp from to ! ->

Router is configured to allow routing:

pf.conf(5) tell me it will do translation on pass through packets:
      Translation rules apply only to packets that pass through the 
      interface,	and if no interface is specified, translation is applied 
      packets on	all interfaces.

Looking at tcpdump of the router I do not see packages been translated 
yet only being forwarded, which leaves me wondering could this be done 
at all?

Best regards,

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