Re: Late to the party - multiple search domains on the network.

[Dan Williams <dcbw redhat com>]

On Mon, 2005-04-11 at 13:53 +0100, Simon Kelley wrote:
> Dan Williams wrote:
> 
> > Note that at some soon point we're going to switch to using dhclient rather than 
> > our internal DHCP client.  Jason VasDias at Red Hat is adding in the support to 
> > dhclient that would be required to use it with NetworkManager.  That should fix 
> > up most compatibility problems too.
> > 
> > Dan
> > 

> The current plan has an interface an a d-bus object, with methods to
> 
> . Set/query current DHCP lease status (address and expiry times)
> . Obtain a new lease.
> . Release a lease.
> . Renew a lease.
> . Query a configuration setting from the DHCP server. (using DHCPINFORM, 
> and cached.)

This sounds exactly what what's needed.

> It will be the responsibility of the user of this interface to pass the 
> configuration information to the system, and act on it by setting 
> default routes, etc. The only part of the kernel's state which will be 
> directly manipulated by the DHCP client will be interface address and 
> up/down status. (This is because the client has to be sure that the 
> interface will come down at the end of a lease, to keep the network 
> stable.)

Well, in a NetworkManager world, NM controls the interface's address and
up/down state, not the DHCP client.  Ideally, the DHCP client would
simply publish that information via DBUS, and also a few assorted
signals like:

1) DHCP transaction failed
2) DHCP Lease ended
3) DHCP rebind/renew completed

etc, and NetworkManager (or _any_ client of the DHCP service) would do
what it needed to with that information.  I guess that if you kept that
logic in the DHCP client, NM would notice that the interface was down
and simply reactivate it right away.

The problem I run into a lot is that too many other programs try to do
too much, because nobody is thinking about the larger picture.  The
dhclient scripts are a pile of crap right now because they try to do
everything, which is one reason I didn't use dhclient in the first
place.  Second, things like "nifd" send out interface up/down events,
which is what NetworkManager also does.  Then we have things like
"wpa_supplicant" that do their _own_ WEP key configuration, their own
wireless scanning, their own interface up/down stuff.  Its all quite a
mess.

> Does that sound like it might be useful for networkmanager? I wouldn't 
> expect you to commit to it ATM ("show us the code" and all that), but it 
> will certainly happen, so you might want to bear it in mind. OTOH that 
> might be the sort of thing Jason VasDias is doing with dhclient, so I 
> could pick  up his work for the applications I have in mind.

I think that it would be really, really, really great to standardize
(more or less) on a DHCP service model using dbus that both dnsmasq and
dhclient could provide.  That way, it wouldn't matter which client
people used, and most DHCP clients provide the same information.  As
soon as I can toss the internal dhcpcd to the dogs, I certainly will.

Thanks for the interest!  The more we can do with dbus and the less with
hack-tower shell scripts, the better.

Dan