freebsd-skq/share/man/man5/nsswitch.conf.5
Jacques Vidrine 248aee623c Add nsswitch support. By creating an /etc/nsswitch.conf file, you can
configure FreeBSD so that various databases such as passwd and group can be
looked up using flat files, NIS, or Hesiod.

= Hesiod has been added to libc (see hesiod(3)).

= A library routine for parsing nsswitch.conf and invoking callback
  functions as specified has been added to libc (see nsdispatch(3)).

= The following C library functions have been modified to use nsdispatch:
    . getgrent, getgrnam, getgrgid
    . getpwent, getpwnam, getpwuid
    . getusershell
    . getaddrinfo
    . gethostbyname, gethostbyname2, gethostbyaddr
    . getnetbyname, getnetbyaddr
    . getipnodebyname, getipnodebyaddr, getnodebyname, getnodebyaddr

= host.conf has been removed from src/etc.  rc.network has been modified
  to warn that host.conf is no longer used at boot time.  In addition, if
  there is a host.conf but no nsswitch.conf, the latter is created at boot
  time from the former.

Obtained from:	NetBSD
2000-09-06 18:16:48 +00:00

267 lines
7.5 KiB
Groff

.\" $NetBSD: nsswitch.conf.5,v 1.14 1999/03/17 20:19:47 garbled Exp $
.\" $FreeBSD$
.\"
.\" Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Luke Mewburn.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by Luke Mewburn.
.\" 4. The name of the author may not be used to endorse or promote products
.\" derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.Dd January 22, 1998
.Dt NSSWITCH.CONF 5
.Os
.Sh NAME
.Nm nsswitch.conf
.Nd name-service switch configuration file
.Sh DESCRIPTION
The
.Nm
file specifies how the
.Xr nsdispatch 3
(name-service switch dispatcher) routines in the C library should operate.
.Pp
The configuration file controls how a process looks up various databases
containing information regarding hosts, users (passwords), groups, etc.
Each database comes from a source (such as local files, DNS, and
.Tn NIS ) ,
and the order to look up the sources is specified in
.Nm nsswitch.conf .
.Pp
Each entry in
.Nm
consists of a database name, and a space separated list of sources.
Each source can have an optional trailing criterion that determines
whether the next listed source is used, or the search terminates at
the current source.
Each criterion consists of one or more status codes, and actions to
take if that status code occurs.
.Ss Sources
The following sources are implemented:
.Bl -column "compat" -offset indent -compact
.Sy Source Description
.It files Local files, such as
.Pa /etc/hosts ,
and
.Pa /etc/passwd .
.It dns Internet Domain Name System.
.Dq hosts
and
.Sq networks
use
.Sy IN
class entries, all other databases use
.Sy HS
class (Hesiod) entries.
.It nis NIS (formerly YP)
.It compat support
.Sq +/-
in the
.Dq passwd
and
.Dq group
databases.
If this is present, it must be the only source for that entry.
.El
.Ss Databases
The following databases are used by the following C library functions:
.Bl -column "networks" -offset indent -compact
.Sy Database Used by
.It group
.Xr getgrent 3
.It hosts
.Xr gethostbyname 3
.It networks
.Xr getnetbyname 3
.It passwd
.Xr getpwent 3
.It shells
.Xr getusershell 3
.El
.Ss Status codes
The following status codes are available:
.Bl -column "tryagain" -offset indent -compact
.Sy Status Description
.It success The requested entry was found.
.It notfound The entry is not present at this source.
.It tryagain The source is busy, and may respond to retries.
.It unavail The source is not responding, or entry is corrupt.
.El
.Ss Actions
For each of the status codes, one of two actions is possible:
.Bl -column "continue" -offset indent -compact
.Sy Action Description
.It continue Try the next source
.It return Return with the current result
.El
.Ss Format of file
A
.Tn BNF
description of the syntax of
.Nm
is:
.Bl -column "<criterion>" -offset indent
.It <entry> ::=
<database> ":" [<source> [<criteria>]]*
.It <criteria> ::=
"[" <criterion>+ "]"
.It <criterion> ::=
<status> "=" <action>
.It <status> ::=
"success" | "notfound" | "unavail" | "tryagain"
.It <action> ::=
"return" | "continue"
.El
.Pp
Each entry starts on a new line in the file.
A
.Sq #
delimits a comment to end of line.
Blank lines are ignored.
A
.Sq \e
at the end of a line escapes the newline, and causes the next line to
be a continuation of the current line.
All entries are case-insensitive.
.Pp
The default criteria is to return on
.Dq success ,
and continue on anything else (i.e,
.Li [success=return notfound=continue unavail=continue tryagain=continue]
).
.Ss Compat mode: +/- syntax
In historical multi-source implementations, the
.Sq +
and
.Sq -
characters are used to specify the importing of user password and
group information from
.Tn NIS .
Although
.Nm
provides alternative methods of accessing distributed sources such as
.Tn NIS ,
specifying a sole source of
.Dq compat
will provide the historical behaviour.
.Pp
An alternative source for the information accessed via
.Sq +/-
can be used by specifying
.Dq passwd_compat: source .
.Dq source
in this case can be
.Sq dns ,
.Sq nis ,
or
any other source except for
.Sq files
and
.Sq compat .
.Ss Notes
Historically, many of the databases had enumeration functions, often of
the form
.Fn getXXXent .
These made sense when the databases were in local files, but don't make
sense or have lesser relevance when there are possibly multiple sources,
each of an unknown size.
The interfaces are still provided for compatibility, but the source
may not be able to provide complete entries, or duplicate entries may
be retrieved if multiple sources that contain similar information are
specified.
.Pp
To ensure compatibility with previous and current implementations, the
.Dq compat
source must appear alone for a given database.
.Ss Default source lists
If, for any reason,
.Nm nsswitch.conf
doesn't exist, or it has missing or corrupt entries,
.Xr nsdispatch 3
will default to an entry of
.Dq files
for the requested database.
Exceptions are:
.Bl -column passwd_compat "dns files" -offset indent
.Sy Database Default source list
.It group compat
.It group_compat nis
.It hosts dns files
.It passwd compat
.It passwd_compat nis
.El
.Sh FILES
.Bl -tag -width /etc/nsswitch.conf -compact
.It Pa /etc/nsswitch.conf
The file
.Nm
resides in
.Pa /etc .
.El
.Sh EXAMPLES
To lookup hosts in
.Pa /etc/hosts
and then from the DNS, and lookup user information from
.Tn NIS
then files, use:
.Bl -column "passwd:" -offset indent
.It hosts: files dns
.It passwd: nis [notfound=return] files
.It group: nis [notfound=return] files
.El
.Pp
The criteria
.Dq [notfound=return]
sets a policy of "if the user is notfound in nis, don't try files."
This treats nis as the authoritive source of information, except
when the server is down.
.Sh SEE ALSO
.Xr nsdispatch 3 ,
.Xr resolv.conf 5 ,
.Xr named 8 ,
.Xr ypbind 8
.Sh HISTORY
The
.Nm
file format first appeared in
.Fx 4.1 .
It was imported from the
.Nx
Project, where it appeared first in
.Nx 1.4 .
.Sh AUTHORS
Luke Mewburn
.Aq lukem@netbsd.org
wrote this freely distributable name-service switch implementation,
using ideas from the
.Tn ULTRIX
.Xr svc.conf 5
and
.Tn Solaris
.Xr nsswitch.conf 4
manual pages.