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

Dan Williams wrote:
On Mon, 2005-04-11 at 19:15 +0100, Simon Kelley wrote:

. Best to decouple the option space from the DHCP spec, and especially the DHCP option numbers. There are probably configuration items which don't map to DHCP well, and some DHCP options which don't have single option numbers. (for instance, the proposed DHCP spec for proxies lumps FTP, HTTP, SSL, SOCKS etc proxies under a single option number.) Also some configuration might come from other sources (PPP can supply DNS servers and default route, at least)

Well, this would be a great system-wide D-BUS service.  I wasn't going
to go there for now, since that is a major change and a bunch of work,
but think of something like this:

A NetworkInformation service (apologies to NIS) that stores all this
data both system-wide, and per-user.  Sort of like GConf does multi-
level config, but not depending on GNOME in any way.

Services like DHCP clients would push their options to the NI service,
which would store generic network config values like DNS servers, domain
names, NTP servers, the rest of the DHCP options, but also system-level
configuration of such things that the user set in system-config-network,
YAST, gnome-system-tools, etc.

I guess the point is that these options can come from more sources than
DHCP, like you say, but there's no central framework to manage them
from.  Also, such a daemon should _not_ enforce any policy, simply
provide an information store from a variety of sources and provide that
information on demand to clients like NetworkManager, traditional
network config scripts, BIND/named/dnsmasq, ntpd, etc.

But you also get into the problems of "What's my current DNS server?"
when you're on a PPP connection and have a VPN active.  The PPP
connection has its own DNS servers, but the VPN connection might also
have its own DNS servers.  How do you present that information to the
rest of the system?  A "stack" approach where PPP pushes its info, then
VPN pushes its info on top?  Or "last config wins"?  Both of those
solutions have problems though.  Much of this information is per-
interface too, but things like DNS servers, hostname, and domain names
are generally not.

I think the simplest way to solve the "which source do I use for configuration information" problem is just to use a simple extension on the current netapplet-like system.

Something like netapplet allows the user to set the addresses for the DNS servers, timeservers etc, and to switch between different configurations to cope with changing network connections. The trick is extend the configuration options so that as well as "my nameserver is at" it's possible to say "The nameserver comes from DHCP on eth0". Add NetworkManager automatic switching between configurations and you have everything you need. To take your example, I can have a configuration where the DNS server setting is "get it from the VPN" and another for just doing dialup where its "get it from PPP".



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