Which IP do I tunnel? The one that I see on "ip a" command or the natted one?

[networkloser]

I access server via this IP = abc

When I do ip a on server, I get this IP = def

Now the database server...

Its ip is ghi and its mapped to jkl.

Now tell me how do I tunnel this?

[networkloser]

https://i.stack.imgur.com/SAbCk.png
This is the the moba that I use. Tell me in this format sir. Also don't forget to tell me the reason.

[deanwebb]

There's no need for tunnelling in this example. Tunnelling is done when there is a security requirement or an incompatible protocol (like IPv6 on an IPv4 backbone). If it is application-to-application tunnelling, typically that is done within the application itself and runs with the TCP/IP settings on the computer, with no need for intervention from the user or sysadmin.

Since all the devices are on IPv4, there's no need for a protocol tunnel in this example. The firewall shows a tunnel, but that is more just permitting traffic back and forth.