Ubuntu Manpage: rpc.yppasswdd - NIS password update daemon

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

AUTHOR

       Olaf Kirch, <okir@monad.swb.de>
       Thorsten Kukuk, <kukuk@suse.de>