NetworkManager-resolv.conf -

[Tim]

On Fri, 2012-11-16 at 11:01 +0000, Timothy Murphy wrote:
> In my view, the action of NM in over-writing /etc/resolv.conf
> is completely illogical.
> There is no conceivable situation in which this might help.

In just about all networks that you don't personally manage, a DHCP
server is used to configure the clients.  Very few organisations will
want to waste time individually configuring each machine on each actual
machine, they want to do it centrally.

As you connect, whether that be NetworkManager handling your DCHP
client, or something else, all the network parameters are set to suit
the network that you're connecting to.  If you leave parameters in its
configuration that are set for some other network, such as by not
rewriting resolv.conf to suit the current network, then you stand a very
good chance of having a network that does NOT work.

> Also, in my experience NM does NOT get the DNS settings from the
> server.

Your experience must have some faults in it.  Because that's exactly how
it gets them.  The only way that NetworkManager mightn't get configured
is if the DHCP server serving it is not set up right.

Upon connection, the DHCP server tells the DHCP client all manner of
things.  From the basic: this is your hostname, your IP address, these
are your DNS servers, this is your gateway IP out of this network.  To
even more information that /can/ be supplied, such as the addresses for
your printserver, your NTP server, and other local resources.

It has done this for me on my own LAN, successfully configured
everything when connecting to another LAN, and successfully reconfigured
itself for my LAN when I returned.  So, that sort of thing has
definitely worked fine, for me.

One area that I have seen not always work well is handling reconnecting
to a network upon recovery of a lost signal.  But it's a case of being
inappropriately asked to logon, when it should simply just reconnect.
> 
> But if I go out of WiFi range then NM comments out the DNS entries 
> in /etc/resolv.conf .

As such details are of no use, when not actually connected to the
network that such details pertain to.

> However, if I go back in range, it does not add the DNS entries
> from /etc/dhcp/dhcpd.conf on the server,

That sort of thing works here, and has for as long as I recall using
wireless (Fedora 9, 11, and some others that I've tested, but can't
recall which on which machine).

>  where I have
>   # option definitions common to all supported networks...
>   option domain-name "gayleard.com";
>   option domain-name-servers 159.134.237.6,159.134.248.17;
> 
> I'm not sure what you mean by "the GUI".

NetworkManager (in the past) only doing something when logged into a
graphical environment, e.g. Gnome or KDE.  Not only was there not an
interface for the command line, for the user to deal with it.  I don't
recall that it actually did anything until you logged into a graphical
desktop.  Though, this is historical, by now.

> If you mean Network Management Settings, I see nothing there
> that would allow me to alter the settings in /etc/resolv.conf .

When one clicks on the NetworkManager icon (I don't recall whether it's
left-click or right-click), there's an edit connections choice in the
menu that pops up.  One can, then, navigate one's way over to the
listing for the current network connection, and edit parameters specific
to it.  In the case of resolv.conf related data, you can edit name
servers that NetworkManager will actually use.  To be honest, I do not
care whether it actually puts them into that file, or not, but that's
the effect that it has.

-- 
[tim at localhost ~]$ uname -r
2.6.27.25-78.2.56.fc9.i686

Don't send private replies to my address, the mailbox is ignored.  I
read messages from the public lists.