Different IP for in and out requests

[Mathilde]

Hi !
I am currently setting up  the network for the server room of the IT association of my school.

Here is what it should look like:


I only have control of what is in the Server Room.
The problem is that my school blocks all unknown trafic from acvcessing the internet with a captive portal.
I had 1 IP unlocked meaning it can access the internet without registering with the captive portal. (it's 10.200.1.1)

The probem is that is that I need all servers to access the internet freely (i.e. use the unblocked IP using NAT) and also be accessible from the internal network (by 10.200.x.x for example) with their own dedicated IP (I know the free ranges, but the IT department won't unblock more than 1 IP).

I've been trying to configure 1:1 NAT and but without luck... (I managed to make BINAT work but the trafic to the internet would not be translated to the unblocked IP obviously... )

How am I supposed to do it ?

Thank you all !