The Kerberos 5 SU authentication component provides functions to verify
the identity of a user
and determine whether or not the user is authorized to obtain the
privileges of the target account.
If the target account is
then the Kerberos 5 principal used
for authentication and authorization will be the
the current user, e.g.
Otherwise, the principal will simply be the current user's default
The user is prompted for a password if necessary.
Authorization is performed
by comparing the Kerberos 5 principal with those listed in the
file in the target account's home directory
The following options may be passed to the authentication module:
debugging information at
If the authentication module
is not the first in the stack,
and a previous module
obtained the user's password,
that password is used
to authenticate the user.
If this fails,
the authentication module returns failure
without prompting the user for a password.
This option has no effect
if the authentication module
is the first in the stack,
or if no previous modules
obtained the user's password.
This option is similar to the
except that if the previously obtained password fails,
the user is prompted for another password.