How I can hardening qubes .
Qubes aims to ship with secure defaults, so no general hardening should be necessary (unlike an operating system that was not designed primarily with security in mind). Anything not done by default is probably something that depends on the user’s unique situation (use case, threat model, etc.). In other words, if there’s something that all users should do as soon as they install Qubes OS in order to harden the system, then we (the project) should simply make that the default and ship Qubes that way. If we haven’t already done that for a given thing, then it’s probably not something that would be appropriate for every user, or we’re still working on making it the default.