you can do SSH remote port forwading if enabled on server-A.
Run this command on server-B
ssh -R Server-A-port:127.0.0.1:server-B-port -N -f user@Server-A
So now any request hit on server-A:Server-A-portserver-A:Server-A-port it will be passed to server-B:server-B-portserver-B:server-B-port
you can read more about ssh forwading here.