Listen 80, will listen on all lan interfaces, so it will take requests from dmz and answer them on the same interface.
When it comes to passing requests on another lan, you simply need to address this other lan, ea.
proxy_pass http://192.168.123.123;
(Normal) routing will do the rest.
When it comes to passing requests on another lan, you simply need to address this other lan, ea.
proxy_pass http://192.168.123.123;
(Normal) routing will do the rest.