NAME
rpc.yppasswdd - NIS password update daemon
SYNOPSIS
rpc.yppasswdd [-D directory] [-e chsh|chfn] [--port number]
rpc.yppasswdd [-s shadow] [-p passwd] [-e chsh|chfn] [--port number]
rpc.yppasswdd -x program|-E program [-e chsh|chfn] [--port number]
DESCRIPTION
rpc.yppasswdd is the RPC server that lets users change their passwords
in the presence of NIS (a.k.a. YP). It must be run on the NIS master
server for that NIS domain.
When a yppasswd(1) client contacts the server, it sends the old user
password along with the new one. rpc.yppasswdd will search the system’s
passwd file for the specified user name, verify that the given (old)
password matches, and update the entry. If the user specified does not
exist, or if the password, UID or GID doesn’t match the information in
the password file, the update request is rejected, and an error
returned to the client.
If this version of the server is compiled with the CHECKROOT=1 option,
the password given is also checked against the systems root password.
After updating the passwd file and returning a success notification to
the client, rpc.yppasswdd executes the pwupdate script that updates the
NIS server’s passwd.* and shadow.byname maps. This script assumes all
NIS maps are kept in directories named /var/yp/nisdomain that each
contain a Makefile customized for that NIS domain. If no such Makefile
is found, the scripts uses the generic one in /var/yp.
OPTIONS
The following options are available:
-D directory
The passwd and shadow files are located under the specified
directory path. rpc.yppasswdd will use this files, not
/etc/passwd and /etc/shadow. This is useful if you do not want
to give all users in the NIS database automatic access to your
NIS server.
-E program
Instead of rpc.yppasswdd editing the passwd & shadow files, the
specified program will be run to do the editing. The following
environment variables will be set for the program:
YP_PASSWD_OLD, YP_PASSWD_NEW, YP_USER, YP_GECOS, YP_SHELL. The
program should return an exit status of 0 if the change
completes successfully, 1 if the change completes successfully
but pwupdate should not be run, and otherwise if the change
fails.
-p passwdfile
This options tells rpc.yppasswdd to use a different source file
instead of /etc/passwd This is useful if you do not want to give
all users in the NIS database automatic access to your NIS
server.
-s shadowfile
This options tells rpc.yppasswdd to use a different source file
instead of /etc/passwd. See below for a brief discussion of
shadow support.
-e [chsh|chfn]
By default, rpc.yppasswdd will not allow users to change the
shell or GECOS field of their passwd entry. Using the -e option,
you can enable either of these. Note that when enabling support
for ypchsh(1), you have to list all shells users are allowed to
select in /etc/shells.
-x program
When the -x option is used, rpc.yppasswdd will not attempt to
modify any files itself, but will instead run the specified
program, passing to its stdin information about the requested
operation(s). There is a defined protocol used to communicate
with this external program, which has total freedom in how it
propagates the change request. See below for more details on
this.
-m Will be ignored, for compatibility with Solaris only.
--port number
rpc.yppasswdd will try to register itself to this port. This
makes it possible to have a router filter packets to the NIS
ports.
-v --version
Prints the version number and if this package is compiled with
the CHECKROOT option.
MISCELLANEOUS
Shadow Passwords
Using Shadow passwords alongside NIS does not make too much sense,
because the supposedly inaccesible passwords now become readable
through a simple invocation of ypcat(1).
Shadow support in rpc.yppasswdd does not mean that it offers a very
clever solution to this problem, it simply means that it can read and
write password entries in the system’s shadow file. You have to
produce a shadow.byname NIS map to distribute password information to
your NIS clients. rpc.yppasswdd will search at first in the /etc/passwd
file for the user and password. If it find’s the user, but the password
is "x" and a /etc/shadow file exists, it will update the password in
the shadow map.
Use of the -x option
The program should expect to read a single line from stdin, which is
formatted as follows:
<username> o:<oldpass> p:<password> s:<shell> g:<gcos>\n
where any of the three fields [p, s, g] may or may not be present.
This program should write "OK\n" to stdout if the operation succeeded.
On any other result, rpc.yppasswdd will report failure to the client.
Note that the program specified by the -x option is responsible for
doing any NIS make and build, and for doing any necessary validation on
the shell and gcos field information supplied. The password passed to
the client will be in UNIX crypt() format.
Logging
rpc.yppasswdd logs all password update requests to syslogd(8)’s auth
facility. The logging information includes the originating host’s IP
address and the user name and UID contained in the request. The user-
supplied password itself is not logged.
Security
Unless I’ve screwed up completely (as I did with versions prior to
version 0.5), rpc.yppasswdd should be as secure or insecure as any
program relying on simple password authentication. If you feel that
this is not enough, you may want to protect rpc.yppasswdd from outside
access by using the ‘securenets’ feature of the new portmap(8)
version 3. Better still, use Kerberos.
COPYRIGHT
rpc.yppasswdd is copyright (C) Olaf Kirch. You can use and distribute
it under the GNU General Public License Version 2. Note that it does
not contain any code from the shadow password suite.
FILES
/usr/sbin/rpc.yppasswdd
/usr/lib/yp/pwupdate
/etc/passwd
/etc/shadow
SEE ALSO
passwd(5), shadow(5), passwd(1), yppasswd(1), ypchsh(1), ypchfn(1),
ypserv(8), ypcat(1)
The Network Information Service (NIS) was formerly known as Sun Yellow
Pages (YP). The functionality of the two remains the same; only the
name has changed. The name Yellow Pages is a registered trademark in
the United Kingdom of British Telecommunications plc, and may not be
used without permission.
AUTHOR
Olaf Kirch, <okir@monad.swb.de>
Thorsten Kukuk, <kukuk@suse.de>