110 lines
3.6 KiB
Groff
110 lines
3.6 KiB
Groff
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.\" A man page for /etc/default/nss. -*- nroff -*-
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.\"
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.\" Copyright (C) 2006 Red Hat, Inc. All rights reserved.
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.\"
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.\" This copyrighted material is made available to anyone wishing to use,
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.\" modify, copy, or redistribute it subject to the terms and conditions of the
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.\" GNU General Public License v.2.
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.\"
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.\" This program is distributed in the hope that it will be useful, but WITHOUT
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.\" ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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.\" FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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.\" more details.
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.\"
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.\" You should have received a copy of the GNU General Public License along
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.\" with this program; if not, write to the Free Software Foundation, Inc.,
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.\" 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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.\"
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.\" Author: Ulrich Drepper <drepper@redhat.com>
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.TH nss 5 "May 2006" nss
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.SH NAME
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nss \- Name Service Switch configuration file
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.SH DESCRIPTION
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Each call to a function which retrieves data from a system database
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like the password or group database is handled by the Name Service
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Switch implementation in the GNU C library. The various services
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provided are implemented by independent modules, each of which
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naturally varies widely from the other.
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.PP
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The default implementations coming with the GNU C library are by
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default conservative and do not use unsafe data. This might be
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very costly in some situations, especially when the databases
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are large. Some modules allow the system administrator to request
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taking shortcuts if these are known to be safe. It is then the
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system administrator's responsibility to ensure the assumption
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is correct.
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.PP
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There are other modules where the implementation changed over time.
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If an implementation used to sacrifize speed for memory consumption
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it might create problems if the preference is switched.
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.PP
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The \fI/etc/default/nss\fR file contains a number of variable
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assignments. Each variable controls the behavior of one or more
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NSS modules. White spaces are ignored. Lines beginning with `#'
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are treated as comments.
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.PP
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The variables currently recognized are:
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.TP
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\fBNETID_AUTHORITATIVE =\fR \fITRUE\fR|\fIFALSE\fR
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If set to TRUE, the NIS backend for the
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.BR initgroups (3)
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function will accept the information
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from the netid.byname NIS map as authoritative. This can speed up the
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function significantly if the group.byname map is large. The content
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of the netid.byname map is used \fBas is\fR. The system administrator has
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to make sure it is correctly generated.
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.TP
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\fBSERVICES_AUTHORITATIVE =\fR \fITRUE\fR|\fIFALSE\fR
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If set to TRUE, the NIS backend for the
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.BR getservbyname (3)
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and
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.BR getservbyname_r (3)
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function will assume
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services.byservicename NIS map exists and is authoritative, particularly
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that it contains both keys with /proto and without /proto for both
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primary service names and service aliases. The system administrator
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has to make sure it is correctly generated.
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.TP
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\fBSETENT_BATCH_READ =\fR \fITRUE\fR|\fIFALSE\fR
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If set to TRUE, the NIS backend for the
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.BR setpwent (3)
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and
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.BR setgrent (3)
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functions will read the entire
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database at once and then hand out the requests one by one from
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memory with every corresponding
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.BR getpwent (3)
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or
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.BR getgrent (3)
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call respectively. Otherwise each
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.BR getpwent (3)
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or
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.BR getgrent (3)
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call might result into a network communication with the server to get
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the next entry.
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.SH EXAMPLE
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The default configuration corresponds to the
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following configuration file:
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.nf
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NETID_AUTHORITATIVE=FALSE
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SERVICES_AUTHORITATIVE=FALSE
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SETENT_BATCH_READ=FALSE
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.SH FILES
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\fI/etc/default/nss\fR
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.SH AUTHOR
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Ulrich Drepper <drepper@redhat.com>
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.SH SEE ALSO
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\fInsswitch.conf\fR
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