I have problem with IP public, my Network configuration

[wireless] <------> [Router] <------ > [ Linux proxy ] < ------ > [Client ]

IP configuration
[202.123.123.1] <------->[202.123.123.2 and 192.168.0.1] < ------ > [192.168.0.2 and 202.123.123.3] < ------ > [202.123.123.4]


this configuration will use IP 202.123.123.2 on internet
how to config my network to use IP Client 202.123.123.4 on internet

you can create a virtual nic on the linux proxy -

eth0 being 202.123.123.2
eth0:1 being 202.123.123.4

if that is what you are looking for ...

also, is [client] too directly connected to the internet via ip 202.123.123.3 as well as to the local network using the 192.168 subnet?

it's not work

[202.123.123.1] <------->[eth0:202.123.123.2 and eth1:192.168.0.1] < ------ > [eth0:192.168.0.2 and eth1:202.123.123.3] < ------ > [eth0:202.123.123.4]

any idea??

I am extremely sorry ... did not read the diagram right as it had wrapped around ....

It looks to me like your trouble is occuring at the router. Many personal and dsl routers do NAT, meaning the router pretends that it is the one sending the information. Unsolicited information coming the other way is then stopped at the router. It sounds as though you are trying to get your client machine visable on the public network. To do that you will need to configure your router (assumeing that is where the problem lies). Different routers use different terms; some say "NAT", others "firewall", some will require you to set up a "bridge".

What are you attempting to do, by the way? If you need to host a service on the public internet you may just need to set up port forwarding (pin holes) on your router. That would be the prefered method.