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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 utility allows users to change their NIS passwords and certain
56 other information using the
64 is an RPC-based server that accepts incoming password change requests,
65 authenticates them, places the updated information in the
66 .Pa /var/yp/master.passwd
67 template file and then updates the NIS
75 utility allows a normal NIS user to change
76 his or her NIS password, full name (also
77 known as 'GECOS' field) or shell.
78 These updates are typically done using
86 (Some administrators don't want users to be able to change their
87 full name information or shells; the server can be invoked with option flags
88 that disallow such changes.)
89 When the server receives an update request,
90 it compares the address of the client making the request against the
93 .Pa /var/yp/securenets .
96 manual page for more information on securenets; the
98 utility uses the same access control mechanism as
102 checks the 'old' password supplied by the user to make sure it's
103 valid, then performs some sanity checks on the updated information (these
104 include checking for embedded control characters, colons or invalid shells).
105 Once it is satisfied that the update request is valid, the server modifies
106 the template password file (the default is
107 .Pa /var/yp/master.passwd )
109 .Pa /usr/libexec/yppwupdate
110 script to rebuild the NIS maps.
111 (This script has two arguments passed
112 to it: the absolute pathname of the password template that was modified
113 and the name of the domain that is to be updated.
116 .Pa /var/yp/Makefile ) .
122 also allows the super-user on the NIS master server to perform more
123 sophisticated updates on the NIS passwd maps.
124 The super-user can modify
125 any field in any user's master.passwd entry in any domain, and can
126 do so without knowing the user's existing NIS password (when the server
127 receives a request from the super-user, the password authentication
128 check is bypassed). Furthermore, if the server is invoked with the
130 flag, the super-user can even add new entries to the maps using
132 Again, this only applies to the super-user on the NIS
133 master server: none of these special functions can be performed over
138 utility can only be run on a machine that is an NIS master server.
140 The following options are available:
141 .Bl -tag -width indent
142 .It Fl t Ar master.passwd template file
145 assumes that the template file used to generates the
149 maps for the default domain is called
150 .Pa /var/yp/master.passwd .
151 This default can be overridden by specifying an alternate file name
156 Note: if the template file specified with this flag is
157 .Pa /etc/master.passwd ,
159 will also automatically invoke
161 to rebuild the local password databases in addition to the NIS
166 utility can support multiple domains, however it must
167 choose one domain as a default.
168 It will try to use the system default domain name as set by the
170 command for this default.
172 if the system domain name is not
173 set, a default domain must be specified on
175 If the system default domain is set,
176 then this option can be used to override it.
178 This option can be used to override the default path to
179 the location of the NIS
181 The compiled-in default path is
184 Disallow changing of shell information.
186 Disallow changing of full name ('GECOS') information.
188 Allow additions to be made to the NIS passwd databases.
189 The super-user on the
190 NIS master server is permitted to use the
192 command to perform unrestricted modifications to any field in a user's
197 is started with this flag, it will also allow the super-user to add new
198 records to the NIS passwd maps, just as is possible when using
200 to modify the local password database.
202 Turn on multi-domain mode.
205 can handle several simultaneous domains, most implementations of
207 can only operate on a single NIS domain, which is generally the same as
208 the system default domain of the NIS master server.
212 attempts to overcome this problem in spite of the inherent limitations
215 protocol, which does not allow for a
217 argument in client requests.
218 In multi-domain mode,
220 will search through all the passwd maps of all the domains it
223 until it finds an entry that matches the user information specified in
224 a given update request.
225 (Matches are determined by checking the username,
227 The matched entry and corresponding domain are then
230 Note that in order for multi-domain mode to work, there have to be
231 separate template files for each domain.
232 For example, if a server
233 supports three domains,
238 there should be three separate master.passwd template files called
239 .Pa /var/yp/foo/master.passwd ,
240 .Pa /var/yp/bar/master.passwd ,
242 .Pa /var/yp/baz/master.passwd .
245 happens to be the system default domain, then its template file can
247 .Pa /var/yp/foo/master.passwd
249 .Pa /var/yp/master.passwd .
250 The server will check for the latter file first and then use the former
253 Multi-domain mode is off by default since it can fail if there are
254 duplicate or near-duplicate user entries in different domains.
256 will abort an update request if it finds more than one user entry that
257 matches its search criteria.
258 Even so, paranoid administrators
259 may wish to leave multi-domain mode disabled.
263 is invoked with this flag, it will perform map updates in place.
265 means that instead of just modifying the password template file and
266 starting a map update, the server will modify the map databases
268 This is useful when the password maps are large: if, for
269 example, the password database has tens of thousands of entries, it
270 can take several minutes for a map update to complete.
272 maps in place reduces this time to a few seconds.
274 Turn on verbose logging mode.
275 The server normally only logs messages
278 facility when it encounters an error condition, or when processing
279 updates for the super-user on the NIS master server.
283 flag will cause it to log informational messages for all updates.
287 clients do not use a reserved port when sending requests to
289 This is either because the
291 program is not installed set-uid root, or because the RPC
292 implementation does not place any emphasis on binding to reserved
293 ports when establishing client connections for the super-user.
296 expects to receive requests from clients using reserved ports; requests
297 received from non-privileged ports are rejected.
299 behavior prevents any client systems that to not use privileged
300 ports from successfully submitting password updates.
306 disables the privileged port check so that it will work with
308 clients that don't use privileged ports.
309 This reduces security to
310 a certain small degree, but it might be necessary in cases where it
311 is not possible to change the client behavior.
313 Display the list of flags and options understood by
317 .Bl -tag -width Pa -compact
318 .It Pa /usr/libexec/yppwupdate
319 The script invoked by
321 to update and push the NIS maps after
323 .It Pa /var/yp/master.passwd
324 The template password file for the default domain.
325 .It Pa /var/yp/[domainname]/[maps]
326 The NIS maps for a particular NIS domain.
327 .It Pa /var/yp/[domainname]/master.passwd
328 The template password file(s) for non-default domains
329 (used only in multi-domain mode).
337 As listed in the yppasswd.x protocol definition, the YPPASSWDPROC_UPDATE
338 procedure takes two arguments: a V7-style passwd structure containing
339 updated user information and the user's existing unencrypted (cleartext)
343 is supposed to handle update requests from remote NIS client machines,
346 and similar client programs will in fact be transmitting users' cleartext
347 passwords over the network.
349 This is not a problem for password updates since the plaintext password
350 sent with the update will no longer be valid once the new encrypted password
351 is put into place, but if the user is only updating his or her 'GECOS'
352 information or shell, then the cleartext password sent with the update
353 will still be valid once the update is completed.
355 insecure, this cleartext password could be intercepted and used to
356 gain unauthorized access to the user's account.
358 .An Bill Paul Aq wpaul@ctr.columbia.edu