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38 .Nd "server for updating NIS passwords"
41 .Op Fl t Ar master.passwd template file
42 .Op Fl d Ar default domain
55 daemon allows users to change their NIS passwords and certain
56 other information using the
62 is an RPC-based server that accepts incoming password change requests,
63 authenticates them, places the updated information in the
64 .Pa /var/yp/master.passwd
65 template file and then updates the NIS
73 server allows a normal NIS user to change
74 his or her NIS password, full name (also
75 known as 'GECOS' field) or shell.
76 These updates are typically done using
84 (Some administrators don't want users to be able to change their
85 full name information or shells; the server can be invoked with option flags
86 that disallow such changes.)
87 When the server receives an update request,
88 it compares the address of the client making the request against the
91 .Pa /var/yp/securenets .
94 manual page for more information on securenets; the
96 server uses the same access control mechanism as
100 checks the 'old' password supplied by the user to make sure it's
101 valid, then performs some sanity checks on the updated information (these
102 include checking for embedded control characters, colons or invalid shells).
103 Once it is satisfied that the update request is valid, the server modifies
104 the template password file (the default is
105 .Pa /var/yp/master.passwd )
107 .Pa /usr/libexec/yppwupdate
108 script to rebuild the NIS maps.
109 (This script has two arguments passed
110 to it: the absolute pathname of the password template that was modified
111 and the name of the domain that is to be updated.
114 .Pa /var/yp/Makefile ) .
120 also allows the super-user on the NIS master server to perform more
121 sophisticated updates on the NIS passwd maps.
122 The super-user can modify
123 any field in any user's master.passwd entry in any domain, and can
124 do so without knowing the user's existing NIS password (when the server
125 receives a request from the super-user, the password authentication
126 check is bypassed). Furthermore, if the server is invoked with the
128 flag, the super-user can even add new entries to the maps using
130 Again, this only applies to the super-user on the NIS
131 master server: none of these special functions can be peformed over
136 daemon can only be run on a machine that is an NIS master server.
138 The following options are available:
139 .Bl -tag -width indent
140 .It Fl t Ar master.passwd template file
143 assumes that the template file used to generates the
147 maps for the default domain is called
148 .Pa /var/yp/master.passwd .
149 This default can be overridden by specifying an alternate file name
154 Note: if the template file specified with this flag is
155 .Pa /etc/master.passwd ,
157 will also automatically invoke
159 to rebuild the local password databases in addition to the NIS
164 server can support multiple domains, however it must
165 choose one domain as a default.
166 It will try to use the system default domain name as set by the
168 command for this default.
170 if the system domain name is not
171 set, a default domain must be specified on
173 If the system default domain is set,
174 then this option can be used to override it.
176 This option can be used to override the default path to
177 the location of the NIS
179 The compiled-in default path is
182 Disallow changing of shell information.
184 Disallow changing of full name ('GECOS') information.
186 Allow additions to be made to the NIS passwd databases.
187 The super-user on the
188 NIS master server is permitted to use the
190 command to perform unrestricted modifications to any field in a user's
195 is started with this flag, it will also allow the super-user to add new
196 records to the NIS passwd maps, just as is possible when using
198 to modify the local password database.
200 Turn on multi-domain mode.
203 can handle several simultaneous domains, most implementations of
205 can only operate on a single NIS domain, which is generally the same as
206 the system default domain of the NIS master server.
210 attempts to overcome this problem in spite of the inherent limitations
213 protocol, which does not allow for a
215 argument in client requests.
216 In multi-domain mode,
218 will search through all the passwd maps of all the domains it
221 until it finds an entry that matches the user information specified in
222 a given update request.
223 (Matches are determined by checking the username,
225 The matched entry and corresponding domain are then
228 Note that in order for multi-domain mode to work, there have to be
229 separate template files for each domain.
230 For example, if a server
231 supports three domains,
236 there should be three separate master.passwd template files called
237 .Pa /var/yp/foo/master.passwd ,
238 .Pa /var/yp/bar/master.passwd ,
240 .Pa /var/yp/baz/master.passwd .
243 happens to be the system default domain, then its template file can
245 .Pa /var/yp/foo/master.passwd
247 .Pa /var/yp/master.passwd .
248 The server will check for the latter file first and then use the former
251 Multi-domain mode is off by default since it can fail if there are
252 duplicate or near-duplicate user entries in different domains.
254 will abort an update request if it finds more than one user entry that
255 matches its search criteria.
256 Even so, paranoid administrators
257 may wish to leave multi-domain mode disabled.
261 is invoked with this flag, it will perform map updates in place.
263 means that instead of just modifying the password template file and
264 starting a map update, the server will modify the map databases
266 This is useful when the password maps are large: if, for
267 example, the password database has tens of thousands of entries, it
268 can take several minutes for a map update to complete.
270 maps in place reduces this time to a few seconds.
272 Turn on verbose logging mode.
273 The server normally only logs messages
276 facility when it encounters an error condition, or when processing
277 updates for the super-user on the NIS master server.
281 flag will cause it to log informational messages for all updates.
285 clients do not use a reserved port when sending requests to
287 This is either because the
289 program is not installed set-uid root, or because the RPC
290 implementation does not place any emphasis on binding to reserved
291 ports when establishing client connections for the super-user.
294 expects to receive requests from clients using reserved ports; requests
295 received from non-privileged ports are rejected.
297 behavior prevents any client systems that to not use privileged
298 ports from successfully submitting password updates.
304 disables the privileged port check so that it will work with
306 clients that don't use privileged ports.
307 This reduces security to
308 a certain small degree, but it might be necessary in cases where it
309 is not possible to change the client behavior.
311 Display the list of flags and options understood by
315 .Bl -tag -width Pa -compact
316 .It Pa /usr/libexec/yppwupdate
317 The script invoked by
319 to update and push the NIS maps after
321 .It Pa /var/yp/master.passwd
322 The template password file for the default domain.
323 .It Pa /var/yp/[domainname]/[maps]
324 The NIS maps for a particular NIS domain.
325 .It Pa /var/yp/[domainname]/master.passwd
326 The template password file(s) for non-default domains
327 (used only in multi-domain mode).
335 As listed in the yppasswd.x protocol definition, the YPPASSWDPROC_UPDATE
336 procedure takes two arguments: a V7-style passwd structure containing
337 updated user information and the user's existing unencrypted (cleartext)
341 is supposed to handle update requests from remote NIS client machines,
344 and similar client programs will in fact be transmitting users' cleartext
345 passwords over the network.
347 This is not a problem for password updates since the plaintext password
348 sent with the update will no longer be valid once the new encrypted password
349 is put into place, but if the user is only updating his or her 'GECOS'
350 information or shell, then the cleartext password sent with the update
351 will still be valid once the update is completed.
353 insecure, this cleartext password could be intercepted and used to
354 gain unauthorized access to the user's account.
356 .An Bill Paul Aq wpaul@ctr.columbia.edu