Only allow connections if file (or special condition) is present

[Jörg Tobias Borgert]

Hello!

I was wondering if it possible now (or possible to implement something like
that in the future) that the daemon does only accept connections if a
specific file is present at the moment of the connection request.

I want to achieve that a connection to my server is only possible if I plug
in e.g. an USB stick (which would contain the file) and is always rejected
if that pseudo-hardware-switch isn't set.

My first idea was to symlink the host ceritifcate to
/media/my-usb-stick/certificate-file, but that doesn't feel right.

Thank you very much,

Tobias