We should support dropping all privileges after the daemon is started and all sockets are opened.
We could create a 'gssproxy' user in the system to which we change id after initialization.

The gotcha is that all resources we need access to we'll have to be accessible to this user (/var/lib/gssproxy and all its ccaches and client keytabs).

It may be an optional value in [gssproxy] section of the form:
run_as_user = gssproxy