RPC.YPPASSWDD(8) NIS Reference Manual RPC.YPPASSWDD(8)NAME
rpc.yppasswdd - NIS password update daemon
SYNOPSIS
rpc.yppasswdd [-D directory] -e chsh|chfn [--port number]
[-f|--foreground]
rpc.yppasswdd [-s shadow] [-p passwd] -e chsh|chfn [--port number]
[-f|--foreground]
rpc.yppasswdd -x program | -E program -e chsh|chfn [--port number]
[-f|--foreground]
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.
-f, --foreground
will not put itself into background.
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
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,
look at rpasswdd(8).
FILES
/usr/sbin/rpc.yppasswdd
/usr/lib/yp/pwupdate
/etc/passwd
/etc/shadow
SEE ALSOpasswd(5), shadow(5), passwd(1), rpasswdd(8), yppasswd(1), ypchsh(1),
ypchfn(1), ypserv(8), ypcat(1)AUTHOR
Olaf Kirch <okir@monad.swb.de> and Thorsten Kukuk <kukuk@linux-nis.org>
NIS Reference Manual 09/26/2007 RPC.YPPASSWDD(8)
