[sf-lug] NetworkManager vs cmd line!

[Tom Haddon]

On Sun, 2007-12-30 at 22:20 -0800, Alex Kleider wrote:
> Tom,
> I found myself preparing a posting to the mailing list as follows but
> am reluctant to post it because I'm not sure it's been researched and
> thought out sufficiently. I'm up and running so there is no great
> crisis.
> ..BUT I would like to discuss some of these issues with you. Perhaps at
> the next Monday night JavaCat meeting.

I think there's one coming up next weekend. In any case, happy to
discuss at the next meeting.

> 
> ..cheers!..
> alex
> 
>  > Are you sure your internal router doesn't function as a DNS server?
>  I
> > > know my SBC DSL modem does.
> 
> do you have a modem/router in one box? surely your _modem_ doesn't
> function as a DNS server? I ?also? am working with modem/router combo
> boxes (two installations) and have mixed feelings about having the two
> functions in the same box. Not sure why...

I have a DSL modem from SBC and a Linksys Wireless/Wired Router. DNS is
provided by the DSL modem.

> 
> > 
> My understanding has been that the router gleans from the ISP the DNS
> servers that are available. These then appear to usually be passed on
> to the host that needs the service. I'm NOT aware that the router
> actually itself provides DNS service. 

Mine does, but that doesn't necessarily mean yours does...

> The facts however suggest that at
> least some components of the system feel that it does: i.e. someone
> (?network manager?) puts the router's address into /etc/resolv.config
> (if it is able to! i.e. if the immutable flag isn't set!)
> 
> I'm still having problems with automatic configuration of networking at
> boot up: 
> chattr -i /etc/resolv.conf solved the DNS address overwrite (perhaps by
> network manager, perhaps not;)
> On your suggestion I tried removing NetworkManager and at the same time
> reversed the immutable flag of resolv.conf:
> now I have no network connection until an sudo ifup eth0 command is
> run. 
> I'm guessing that ubuntu is configured to run network manager INSTEAD
> of  a script that sets up networking. 

No, NetworkManager is a layer on top of the standard networking. All
it's doing is automatically setting things that would otherwise manually
need to be done, but it's using the existing networking stack/setup.

> Am I right? If so, then it should
> be replaced by a little script that runs the ifup eth0 command. 
> But all of this is really a work around what ever the real problem is.
> Others don't have to go through these contortions, and initially I
> didn't either, so there must be a fundamental issue that I'm missing.

Yeah, I'm not sure what that could be. My guess is that you're sending
mixed signals to NetworkManager - asking it to configure settings for
some devices, but then trying to force DNS servers, for instance.

> 
> --- Tom Haddon <tom at greenleaftech.net> wrote:
> 
> > > Tom, NetworkManager seems to be my problem: I set up
> > /etc/resolv.conf
> > > with the appropriate servers and then things work; next time I
> > reboot,
> > > resolve.conf contains only the internal IP address of my router;
> > 
> > Are you sure your internal router doesn't function as a DNS server? I
> > know my SBC DSL modem does.
> Please clarify: 
> > Yes, NetworkManager will overwrite resolv.conf if it's being used at
> > all.
> > > Am I right in assuming that the GUI network manager is in fact
> > > NetworkManager? Perhaps I can just turn it off so it's not
> > "helping"
> > > me. The kind of help it's providing I can do without! But ofcourse
> > it
> > > would be nice to figure out what's really  happening and correct
> > the
> > > problem.
> > > 
> > 
> > It sounds like NetworkManager is overwriting the file. Typically it
> > will
> > leave a comment in the file to that effect, though. I would simply
> > remove NetworkManager from your "Sessions" options so that it doesn't
> > startup on session login and see if that fixes (i.e. doesn't
> > overwrite
> > resolv.conf) for you.
> > 
> > Thanks, Tom
> > 
> > > 
> > > 
> > > Cheers, Tom
> > > 
> > > 
> > > a_kleider at yahoo.com
> > > 
> > > 
> > >      
> >
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> > 
> 
> 
> 
> ps if you think this is worthy of a mailing list posting, I'm OK with
> that. Asheesh has chided me in the past for private messages and I have
> no desire to "deny" the list! I'm more worried about posting things
> that are of no interest to the majority.
> 
> 
> a_kleider at yahoo.com
> 
> 
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