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

[Simon Kelley <simon thekelleys org uk>]

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 1.2.3.4" 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".


Cheers,

Simon.