8b6a78c2ec
If rpc.yppasswdd is invoked with the -i flag, password changes will be made to the master.passwd template file and the hash map files in-place, which means it won't have to run a complete map update. Instead, it calls /var/yp/Makefile with the 'pushpw' target, which just pushes the maps to the slaves and runs yp_mkdb -c to tell the local ypserv to flush its database cache. The server will check the passwd.byname and passwd.byuid maps to see if they were built in 'insecure' or 'secure' mode (i.e. with real encrypted passwords in them or without) and update them accordingly. This combined with rpc.ypxfrd greatly reduces the amount of time it takes to complete an NIS password change, especially with very large passwd databases.
326 lines
11 KiB
Groff
326 lines
11 KiB
Groff
.\" Copyright (c) 1995, 1996
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.\" Bill Paul <wpaul@ctr.columbia.edu>. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Bill Paul.
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.\" 4. Neither the name of the author nor the names of contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $Id: rpc.yppasswdd.8,v 1.6 1996/06/03 23:53:21 wpaul Exp $
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.\"
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.Dd February 8, 1996
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.Dt RPC.YPPASSWDD 8
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.Os
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.Sh NAME
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.Nm rpc.yppasswdd
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.Nd "server for updating NIS passwords"
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.Sh SYNOPSIS
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.Nm rpc.yppasswdd
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.Op Fl t Ar master.passwd template file
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.Op Fl d Ar default domain
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.Op Fl p Ar path
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.Op Fl s
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.Op Fl f
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.Op Fl a
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.Op Fl m
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.Op Fl i
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.Op Fl v
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.Op Fl u
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.Op Fl h
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.Sh DESCRIPTION
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The
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.Nm rpc.yppasswdd
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daemon allows users to change their NIS passwords and certain
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other information using the
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.Xr yppasswd 1
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and
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.Xr ypchpass 1
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commands.
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.Nm Rpc.yppasswdd
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is an RPC-based server that accepts incoming password change requests,
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authenticates them, places the updated information in the
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.Pa /var/yp/master.passwd
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template file and then updates the NIS
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.Pa master.passwd
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and
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.Pa passwd
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maps.
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.Pp
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The
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.Nm rpc.yppasswdd
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server allows a normal NIS user to change
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his or her NIS password, full name (also
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known as 'GECOS' field) or shell. These updates are typically done using
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the
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.Xr yppasswd 1 ,
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.Xr ypchfn 1 ,
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.Xr ypchsh 1 ,
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or
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.Xr ypchpass 1
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commands. (Some administrators don't want users to be able to change their
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full name information or shells; the server can be invoked with option flags
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that disallow such changes.) When the server receives an update request,
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it compares the address of the client making the request against the
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.Pa securenets
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rules outlined in
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.Pa /var/yp/securenets .
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(See the
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.Xr ypserv 8
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manual page for more information on securenets; the
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.Nm rpc.yppasswdd
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server uses the same access control mechanism as
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.Xr ypserv 8 .)
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.Pp
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The server then
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checks the 'old' password supplied by the user to make sure it's
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valid, then performs some sanity checks on the updated information (these
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include checking for embedded control characters, colons or invalid shells).
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Once it is satisfied that the update request is valid, the server modifies
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the template password file (the default is
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.Pa /var/yp/master.passwd )
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and then runs the
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.Pa /usr/libexec/yppwupdate
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script to rebuild the NIS maps. (This script has two arguments passed
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to it: the absolute pathname of the password template that was modified
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and the name of the domain that is to be updated. These in turn are
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passed to
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.Pa /var/yp/Makefile ) .
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.Pp
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The FreeBSD version of
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.Nm rpc.yppasswdd
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also allows the super-user on the NIS master server to perform more
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sophisticated updates on the NIS passwd maps. The super-user can modify
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any field in any user's master.passwd entry in any domain, and can
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do so without knowing the user's existing NIS password (when the server
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receives a request from the super-user, the password authentication
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check is bypassed). Furthermore, if the server is invoked with the
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.Fl a
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flag, the super-user can even add new entries to the maps using
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.Xr ypchpass 1 .
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Again, this only applies to the super-user on the NIS
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master server: none of these special functions can be peformed over
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the network.
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.Pp
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The
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.Nm rpc.yppasswdd
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daemon can only be run on a machine that is an NIS master server.
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.Sh OPTIONS
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The following options and flags are supported by
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.Nm rpc.yppasswdd :
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.Bl -tag -width flag
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.It Fl t Ar master.passwd template file
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By default,
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.Nm rpc.yppasswdd
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assumes that the template file used to generates the
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.Pa master.passwd
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and
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.Pa passwd
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maps for the default domain is called
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.Pa /var/yp/master.passwd .
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This default can be overridden by specifying an alternate file name
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with the
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.Fl t
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flag.
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.Pp
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Note: if the template file specified with this flag is
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.Pa /etc/master.passwd ,
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.Nm rpc.yppasswdd
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will also automatically invoke
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.Xr pwd_mkdb 8
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to rebuild the local password databases in addition to the NIS
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maps.
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.It Fl d Ar domain
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The
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.Nm rpc.yppasswdd
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server can support multiple domains, however it must
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choose one domain as a default.
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It will try to use the system default domain name as set by the
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.Xr domainname 1
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command for this default. However,
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if the system domain name is not
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set, a default domain must be specified on
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the command line. If the system default domain is set,
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then this option can be used to override it.
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.It Fl p Ar path
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This option can be used to override the default path to
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the location of the NIS
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map databases. The compiled-in default path is
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.Pa /var/yp .
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.It Fl s
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Disallow changing of shell information.
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.It Fl f
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Disallow changing of full name ('GECOS') information.
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.It Fl a
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Allow additions to be made to the NIS passwd databases. The super-user on the
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NIS master server is permitted to use the
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.Xr ypchpass 1
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command to perform unrestricted modifications to any field in a user's
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.Pa master.passwd
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map entry. When
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.Nm rpc.yppasswdd
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is started with this flag, it will also allow the super-user to add new
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records to the NIS passwd maps, just as is possible when using
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.Xr chpass 1
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to modify the local password database.
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.It Fl m
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Turn on multi-domain mode. Even though
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.Xr ypserv 8
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can handle several simultaneous domains, most implementations of
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.Nm rpc.yppasswdd
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can only operate on a single NIS domain, which is generally the same as
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the system default domain of the NIS master server. The FreeBSD
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.Nm rpc.yppasswdd
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attempts to overcome this problem in spite of the inherent limitations
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of the
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.Pa yppasswd
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protocol, which does not allow for a
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.Pa domain
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argument in client requests. In multi-domain mode,
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.Nm rpc.yppasswdd
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will search through all the passwd maps of all the domains it
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can find under
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.Pa /var/yp
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until it finds an entry that matches the user information specified in
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a given update request. (Matches are determined by checking the username,
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UID and GID fields.) The matched entry and corresponding domain are then
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used for the update.
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.Pp
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Note that in order for multi-domain mode to work, there have to be
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seperate template files for each domain. For example, if a server
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supports three domains,
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.Pa foo ,
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.Pa bar ,
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and
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.Pa baz ,
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there should be three seperate master.passwd template files called
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.Pa /var/yp/foo/master.passwd ,
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.Pa /var/yp/bar/master.passwd ,
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and
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.Pa /var/yp/baz/master.passwd .
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If
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.Pa foo
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happens to be the system default domain, then its template file can
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be either
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.Pa /var/yp/foo/master.passwd
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or
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.Pa /var/yp/master.passwd .
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The server will check for the latter file first and then use the former
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if it can't find it.
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.Pp
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Multi-domain mode is off by default since it can fail if there are
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duplicate or near-duplicate user entries in different domains. The server
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will abort an update request if it finds more than one user entry that
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matches its search criteria. Even so, paranoid administrators
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may wish to leave multi-domain mode disabled.
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.It Fl i
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If
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.Nm rpc.yppasswdd
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is invoked with this flag, it will perform map updates in place. This
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means that instead of just modifying the password template file and
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starting a map update, the server will modify the map databases
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directly. This is useful when the password maps are large: if, for
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example, the password database has tens of thousands of entries, it
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can take several minutes for a map update to complete. Updating the
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maps in place reduces this time to a few seconds.
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.It Fl v
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Turn on verbose logging mode. The server normally only logs messages
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using the
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.Xr syslog 3
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facility when it encounters an error condition, or when processing
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updates for the super-user on the NIS master server. Running the server
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with the
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.Fl v
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flag will cause it to log informational messages for all updates.
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.It Fl u
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Many commercial
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.Xr yppasswd 1
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clients do not use a reserved port when sending requests to
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.Nm rpc.yppasswdd .
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This is either because the
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.Xr yppasswd 1
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program is not installed set-uid root, or because the RPC
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implementation does not place any emphasis on binding to reserved
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ports when establishing client connections for the super-user.
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By default,
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.Nm rpc.yppasswdd
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expects to receive requests from clients using reserved ports; requests
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received from non-privileged ports are rejected. Unfortunately, this
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behavior prevents any client systems that to not use privileged
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ports from sucessfully submitting password updates. Specifying
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the
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.Fl u
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flag to
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.Nm rpc.yppasswdd
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disables the privileged port check so that it will work with
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.Xr yppasswd 1
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clients that don't use privileged ports. This reduces security to
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a certain small degree, but it might be necessary in cases where it
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is not possible to change the client behavior.
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.It Fl h
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Displays the list of flags and options understood by
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.Nm rpc.yppasswdd .
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.El
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.Sh FILES
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.Bl -tag -width Pa -compact
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.It Pa /usr/libexec/yppwupdate
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The script invoked by
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.Nm rpc.yppasswdd
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to update and push the NIS maps after
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an update.
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.It Pa /var/yp/master.passwd
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The template password file for the default domain.
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.It Pa /var/yp/[domainname]/[maps]
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The NIS maps for a particular NIS domain.
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.It Pa /var/yp/[domainname]/master.passwd
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The template password file(s) for non-default domains
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(used only in multi-domain mode).
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.El
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.Sh SEE ALSO
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.Xr ypserv 8 ,
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.Xr yppush 8 ,
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.Xr ypxfr 8 ,
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.Xr yp 4
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.Sh BUGS
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As listed in the yppasswd.x protocol definition, the YPPASSWDPROC_UPDATE
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procedure takes two arguments: a V7-style passwd structure containing
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updated user information and the user's existing unencrypted (cleartext)
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password. Since
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.Nm rpc.yppasswdd
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is supposed to handle update requests from remote NIS client machines,
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this means that
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.Xr yppasswd 1
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and similar client programs will in fact be transmitting users' cleartext
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passwords over the network.
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.Pp
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This is not a problem for password updates since the plaintext password
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sent with the update will no longer be valid once the new encrypted password
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is put into place, but if the user is only updating his or her 'GECOS'
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information or shell, then the cleartext password sent with the update
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will still be valid once the update is completed. If the network is
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insecure, this cleartext password could be intercepted and used to
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gain unauthorized access to the user's account.
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.Sh AUTHOR
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Bill Paul <wpaul@ctr.columbia.edu>
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