.. _.k5login(5):

.k5login
========

DESCRIPTION
-----------

The .k5login file, which resides in a user's home directory, contains
a list of the Kerberos principals.  Anyone with valid tickets for a
principal in the file is allowed host access with the UID of the user
in whose home directory the file resides.  One common use is to place
a .k5login file in root's home directory, thereby granting system
administrators remote root access to the host via Kerberos.


EXAMPLES
--------

Suppose the user ``alice`` had a .k5login file in her home directory
containing just the following line::

    bob@FOOBAR.ORG

This would allow ``bob`` to use Kerberos network applications, such as
ssh(1), to access ``alice``'s account, using ``bob``'s Kerberos
tickets.  In a default configuration (with **k5login_authoritative** set
to true in :ref:`krb5.conf(5)`), this .k5login file would not let
``alice`` use those network applications to access her account, since
she is not listed!  With no .k5login file, or with **k5login_authoritative**
set to false, a default rule would permit the principal ``alice`` in the
machine's default realm to access the ``alice`` account.

Let us further suppose that ``alice`` is a system administrator.
Alice and the other system administrators would have their principals
in root's .k5login file on each host::

    alice@BLEEP.COM

    joeadmin/root@BLEEP.COM

This would allow either system administrator to log in to these hosts
using their Kerberos tickets instead of having to type the root
password.  Note that because ``bob`` retains the Kerberos tickets for
his own principal, ``bob@FOOBAR.ORG``, he would not have any of the
privileges that require ``alice``'s tickets, such as root access to
any of the site's hosts, or the ability to change ``alice``'s
password.


SEE ALSO
--------

kerberos(1)