rpc.yppasswdd(8)

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 speci

fied 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 CHECK

ROOT=1 option,
the password given is also checked against the systems

root password.

After updating the passwd file and returning a success no

tification 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

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 ac

cess 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 suc

cessfully but
pwupdate should not be run, and otherwise if the

change fails.

-p passwdfile

This options tells rpc.yppasswdd to use a differ

ent source file
instead of /etc/passwd This is useful if you do not

want to give
all users in the NIS database automatic ac

cess 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 en

abling 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 de

tails on this.

-m Will be ignored, for compatibility with Solaris on

ly.

--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 be

come 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 infor

mation 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>

where any of the three fields [p, s, g] may or may not be

present.

This program should write "OK0 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 pass

word 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 origi

nating host's IP
address and the user name and UID contained in the re

quest. The usersupplied 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>

YP Server August 2001

RPC.YPPASSWDD(8)