This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
If rpc.yppasswdd is invoked with the -i flag, password changes will
be made to the master.passwd template file and the hash map files
in-place, which means it won't have to run a complete map update.
Instead, it calls /var/yp/Makefile with the 'pushpw' target, which
just pushes the maps to the slaves and runs yp_mkdb -c to tell the
local ypserv to flush its database cache.
The server will check the passwd.byname and passwd.byuid maps to see
if they were built in 'insecure' or 'secure' mode (i.e. with real
encrypted passwords in them or without) and update them accordingly.
This combined with rpc.ypxfrd greatly reduces the amount of time it
takes to complete an NIS password change, especially with very large
passwd databases.
chpass(1) are on the way too.) This version supports all the features
of the old one and adds several new ones:
- Supports real multi-domain operation (optional, can be turned
on with a command-line flag). This means you can actually have
several different domains all served from one NIS server and
allow users in any of the supported domains to change their passwords.
The old yppasswdd only allowed changing passwords in the domain
that was set as the system default domain name on the NIS master
server. The new one can change passwords in any domain by trying
to match the user information passed to it against all the passwd
maps it can find. This is something of a hack, but the yppasswd.x
protocol definiton does not allow for a domain to be passwd as an
argument to rpc.yppasswdd, so the server has no choice but to
grope around for a likely match. Since this method can fail if
the same user exists in two domains, this feature is off by default.
If the feature is turned on and the server becomes confused by
duplicate entries, it will abort the update.
- Does not require NIS client services to be available. NIS servers do
_NOT_ necessarily have to be configured as NIS clients in order to
function: the ypserv, ypxfr and yppush programs I've written recently
will operate fine even if the system domain name isn't set, ypbind isn't
running and there are no magic '+' entries in any of the /etc files.
Now rpc.yppasswdd is the same way. The old yppasswdd would not work
like this because it depended on getpwent(3) and friends to look up
users: this will obviously only work if the system where yppasswdd is
running is configured as an NIS client. The new rpc.yppasswdd doesn't
use getpwent(3) at all: instead it searches through the master.passwd
map databases directly. This also makes it easier for it to handle
multiple domains.
- Allows the superuser on the NIS master server to change any user's
password without requiring password authentication. rpc.yppasswdd
creates a UNIX domain socket (/var/run/ypsock) which it monitors
using the same svc_run() loop used to handle incoming RPC requests.
It also clears all the permission bits for /var/run/ypsock; since
this socket is owned by root, this prevents anyone except root from
successfully connect()ing to it. (Using a UNIX domain socket also
prevents IP spoofing attacks.) By building code into passwd(1) and
chpass(1) to take advantage of this 'trusted' channel, the superuser
can use them to send private requests to rpc.yppasswdd.
- Allows the superuser on the NIS master to use chpass(1) to update _all_
of a user's master.passwd information. The UNIX domain access point
accepts a full master.passwd style structure (along with a domain
name and other information), which allows the superuser to update all
of a user's master.passwd information in the NIS master.passwd maps.
Normal users on NIS clients are still only allowed to change their full
name and shell information with chpass.
- Allows the superuser on the NIS master to _add_ records to the NIS
master.passwd maps using chpass(1). This feature is also switchable
with a command-line flag and is off by default.
