Is there any way to secure network traffic between any two applications with SSL even both applications don't support SSL mode?
Diagram:
(Host X (Application A) ) --------unsecured connection----- (Host Y (Application B) )
(Host X (App. C (App. A)) ) -----secured connection------- (Host Y (App. C (App. B)) )
try stunnel.
and if it does not have to be ssl, try a ssh tunnel.
Depends on the application but almost certainly yes.
For instance you could just setup an IPSec tunnel, or use IPv6 or lots of other ways - talk to us more about your application please.