How to set up a proxy server to work with another machine via VPN?

Question

openvpn

Resources: two machines: one is low-powered (let's say machine A), is in the EU, has a static ip; the second is in Russia (machine B), does not have and will not receive static ip, is relatively powerful, suitable for the tasks set. Both machines are running Ubuntu server.

Purpose: all incoming and outgoing data for machine B should go through machine A, then be transmitted to machine B over an encrypted channel (preferably VPN) and vice versa. Roughly speaking, you need to configure A as a proxy, for the client, working with machine A should be equal to working with machine B, the client should not know the ip of machine B, the traffic should always be encrypted between machine A and B. For the client, this whole bunch should be invisible , as if he always works with machine B, and there is no machine A between him and B. Machine B must be available for external connection through machine A.

I hope I was able to convey the idea, please do not write offtopic

Answer 1

What protocol should the client communicate with the target machine? If something is TCP-based, then it's good. UDP-based - worse, but also possible.
Machine_B initiates a connection to machine_A. Next, set on machine_A Static-NAT (Port-redirect) of the desired port. And yet - Dynamic-NAT so that machine_B receives requests from machine_A.
Or you can do without NAT - means SSh . By the way, then VPN is not needed either - SSh has it all.