path: root/server/keytab-backend.8

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.\"
.IX Title "KEYTAB-BACKEND 8"
.TH KEYTAB-BACKEND 8 "2018-06-03" "1.4" "wallet"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
keytab\-backend \- Extract keytabs from the KDC without changing the key
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
\&\fBkeytab-backend\fR retrieve \fIprincipal\fR
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBkeytab-backend\fR retrieves a keytab for an existing principal from the
\&\s-1KDC\s0 database without changing the current key.  It allows generation of a
keytab for a service without rekeying that service.  It requires a
\&\fBkadmin.local\fR patched to support the \fB\-norandkey\fR option to \fBktadd\fR.
.PP
This script is intended to run under \fBremctld\fR.  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.
.PP
The principal is checked for basic sanity (only accepting alphanumerics,
\&\f(CW\*(C`_\*(C'\fR, and \f(CW\*(C`\-\*(C'\fR with an optional instance and then only alphanumerics,
\&\f(CW\*(C`_\*(C'\fR, \f(CW\*(C`\-\*(C'\fR, and \f(CW\*(C`.\*(C'\fR 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.
.PP
\&\fBkeytab-backend\fR does not do any authorization checks.  Those should be
done by \fBremctld\fR before it is called.
.SH "FILES"
.IX Header "FILES"
.IP "\fI/etc/krb5kdc/allow\-extract\fR" 4
.IX Item "/etc/krb5kdc/allow-extract"
The configuration file that controls which principals can have their
keytabs retrieved.  Blank lines and lines starting with \f(CW\*(C`#\*(C'\fR, as well as
anything after \f(CW\*(C`#\*(C'\fR 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 \fBkeytab-backend\fR.  Any principal that does
not match one of those regular expressions cannot be retrieved.
.IP "\fI/var/lib/keytabs\fR" 4
.IX Item "/var/lib/keytabs"
The temporary directory used for creating keytabs.  \fBkeytab-backend\fR 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.
.SH "AUTHOR"
.IX Header "AUTHOR"
Russ Allbery <eagle@eyrie.org>
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
Copyright 2006\-2008, 2010, 2013 The Board of Trustees of the Leland Stanford
Junior University
.PP
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the \*(L"Software\*(R"),
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:
.PP
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
.PP
\&\s-1THE SOFTWARE IS PROVIDED \*(L"AS IS\*(R", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.\s0  \s-1IN 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.\s0
.PP
SPDX-License-Identifier: \s-1MIT\s0
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fIkadmin.local\fR\|(8), \fIremctld\fR\|(8)
.PP
This program is part of the wallet system.  The current version is
available from <https://www.eyrie.org/~eagle/software/wallet/>.