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.
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.
