Need DHCP client scripts for NIS

Mark Brown broonie at
Tue Jul 8 15:23:22 UTC 2008

On Tue, Jul 08, 2008 at 10:11:34AM -0400, Paul Smith wrote:

> In order for overwriting to occur, the following must be true: the user
> must have installed the NIS package (it's not installed by default on
> Ubuntu), and the user must use DHCP for their network settings, and the
> DHCP server must be configured to provide nis-domain and nis-server
> settings as options (this is rare since only larger enterprises with
> lots of UNIX systems bother with NIS), and finally the user must, for
> some reason, want to use a different value for either/or the NIS domain
> and the NIS servers than the one the DHCP admin suggested.

The main use case this breaks is people using NIS to distribute
information to laptops which then work off-line, potentially on other
networks (I am aware of people doing this, usually with a slave
configured on the laptop for disconnected operation).

Note that the concerns about breaking things apply only to upgrades, not
to new installs which obviously don't have the risk of breaking existing

> Those are a lot of "ifs" and I really don't believe they justify a lot
> of complicated configuration and potentially confusing questions on
> install.  I don't have any problem with a way to disable it if the user
> wants to (a setting in /etc/defaults/nis maybe?  Or maybe they just
> remove these entries from the dhclient.conf request?

This is what low priority debconf questions are for - they're there if
they are needed but not enabled by default so they don't confuse users
in the normal course of affairs.

> There is a change in behavior, potentially, but Ubuntu changes behaviors
> every release.  Finally, remember that the dhclient exit hook preserves

The reason for being especially conservative here is that breaking the
NIS configuration can render the user unable to log in to the system -
the consequences of getting it wrong are extremely serious.

> > For this to be fully useful there would also need to some facility for
> > adding the NIS entries to the passwd, group and shadow files during
> > installation.  This is outside the scope of the NIS package since it
> > affects the global configuration of the system.

> I don't think any change is needed here.  The base system nsswitch.conf
> uses "compat" for the passwd, group, and shadow entries which is fine.

compat is only half the story - you also need to add the appropriate
+:::: entries to the relevant files for it to have any effect.

"You grabbed my hand and we fell into it, like a daydream - or a fever."

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