KEYTAB-BACKEND(8)

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/>.