NAME

       keytab-backend - Extract keytabs from the KDC without changing the key

SYNOPSIS

       keytab-backend retrieve principal

DESCRIPTION

       keytab-backend retrieves a keytab for an existing principal from the KDC database without changing the
       current key.  It allows generation of a keytab for a service without rekeying that service.  It requires
       a kadmin.local patched to support the -norandkey option to ktadd.

       This script is intended to run under remctld.  On success, it prints the keytab to standard output, logs
       a success message to syslog (facility auth, priority info), and exits with status 0.  On failure, it
       prints out an error message, logs an error to syslog (facility auth, priority err), and exits with a non-
       zero status.

       The principal is checked for basic sanity (only accepting alphanumerics, "_", and "-" with an optional
       instance and then only alphanumerics, "_", "-", and "." in the realm) and then checked against a
       configuration file that lists regexes of principals that can be retrieved.  When deploying this software,
       limit as tightly as possible which principals can be downloaded in this fashion.  Generally only shared
       service principals used on multiple systems should be made available in this way.

       keytab-backend does not do any authorization checks.  Those should be done by remctld before it is
       called.

FILES

       /etc/krb5kdc/allow-extract
           The  configuration file that controls which principals can have their keytabs retrieved.  Blank lines
           and lines starting with "#", as well as anything after "#" on a line, are ignored.  All  other  lines
           should  be  Perl  regular  expressions,  one  per  line,  that  match principals whose keytabs can be
           retrieved by keytab-backend.  Any principal that does not match  one  of  those  regular  expressions
           cannot be retrieved.

       /var/lib/keytabs
           The  temporary  directory  used  for creating keytabs.  keytab-backend will create the keytab in this
           directory, make sure that was successful, and then delete the temporary file after the  results  have
           been sent to standard output.

AUTHOR

       Russ Allbery <eagle@eyrie.org>

COPYRIGHT AND LICENSE

       Copyright 2006-2008, 2010, 2013 The Board of Trustees of the Leland Stanford Junior University

       Permission  is  hereby  granted,  free  of  charge,  to  any person obtaining a copy of this software and
       associated documentation files (the "Software"), to deal in the Software without  restriction,  including
       without  limitation  the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
       copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to  the
       following conditions:

       The  above  copyright  notice  and  this permission notice shall be included in all copies or substantial
       portions of the Software.

       THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  IMPLIED,  INCLUDING  BUT  NOT
       LIMITED  TO  THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN
       NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  CLAIM,  DAMAGES  OR  OTHER  LIABILITY,
       WHETHER  IN  AN  ACTION  OF  CONTRACT,  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

       SPDX-License-Identifier: MIT

SEE ALSO

       kadmin.local(8), remctld(8)

       This  program  is   part   of   the   wallet   system.    The   current   version   is   available   from
       <https://www.eyrie.org/~eagle/software/wallet/>.

1.5                                                2024-04-30                                  KEYTAB-BACKEND(8)