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Re: screwed up my network starting



On 28/01/12 09:13 PM, Bob Proulx wrote:
> H.S. wrote:
>> Earlier, my network card was being monitored by network manager.
>> Recently due to various changes, I had the need to give my network card
>> a fixed address. To do so, I took out the following line from
>> /etc/network/interfaces:
>> # The primary network interface
>> #allow-hotplug eth0
>> #NetworkManager#iface eth0 inet dhcp
>>
>> And inserted the following (dhcp address is always a fixed one from the
>> router):
>> auto eth0
>> iface eth0 inet dhcp
> 
> All good.  Or at least okay.
> 
> Instead or in addition to 'auto eth0' you would benefit from having
> 'allow-hotplug eth0' there as well.  That line you commented out is
> good to leave uncommented.  That will allow it to work under the new
> event driven system.  The 'auto eth0' configures it for the older
> static driven system.  (Which is why you get the deprecated message
> when you run 'service networking restart'.)  It is okay to have both
> specified, I usually do.  The format and contents of the file are
> documented here:
> 
>   http://www.debian.org/doc/manuals/debian-reference/ch05.en.html#_the_network_interface_with_the_static_ip


When I dealt with this issue last (a few years ago), I was under the
impression that only one needs to be used. Either I was mistaken then,
or things have improved in the right direction.

> It has become my banner to wave that the netmask is sufficient and
> then the tool can calculate the network and broadcast values.  It is
> better than specifying them.  So if you choose to use the above then
> you would be better off removing the nework and broadcast lines.

Okay.


> It used to be that the debian-installer would create those as
> examples.  But those examples have been removed and the d-i no longer
> creates those.  Recently there has been a push to clean these up so
> that they are no longer distributing such examples.  Here is a
> reference:
> 
>   http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=630551
> 
>> ##     nameserver 208.67.222.222 208.67.220.220

Most likely my mistake.


> Since you are using dhcp to configure the interface then the dhclient
> will set up /etc/resolv.conf as per the information from the dhcpd
> server that gave out the address.  Every time you dhcp an address the
> /etc/resolv.conf will be updated.

Yes, that happens.


> If your usb device appears as a network device I think it may be
> confusing NetworkManager.  It is possible and perhaps likely that
> NetworkManager is trying to set up this newly hotplugged interface,
> that is what NM is designed to do, and then updating /etc/resolv.conf.
> However this being the root of the issue is pure speculation on my
> part.  It seems odd to me that your device would appear as a network
> device.

Seems reasonably. But when this problem occurred, I was using static
address and my resolvconf was probably not working due to my config
errors in interfaces file.

> 
>> The major thing that changed is that I am now using a different
>> router in a shared connection
> 
> The words "in a shared connection" has no meaning to me.  Isn't all
> networking shared by definition?  You can't network a single device.
> It takes two to tango.

I didn't explain properly. The phrase was intended to mean that I am now
using a shared ISP service, and I am using the other party's router.
There are a few quirks in their setup which I would avoid, but that is a
different topic. In any case, I am trying to do minimum changes in their
router's configuration.

Just to elaborate a bit, their router is also a wireless AP. I have
configured my router as a wireless bridge to that AP (Tomato made that
pretty easy).


>> And, how do I setup the nameservers I should be using?
> 
> If you are using DHCP then the DHCP server will specify the
> nameservers to use to the client.  Specify the right nameservers there
> and you will be done.
> 
>> How do I tell this "auto-configuration" to ignore the dhcp
>> nameservers and to use the ones I specify instead?
> 
> I haven't tried this but I would install 'resolvconf' and then specify
> them with the dns-nameservers option listed above.  I think that will
> override the dhcpd nameservers.  I think.
> 
>   auto eth0
>   allow-hotplug eth0
>   iface eth0 inet dhcp
>         dns-search example.com
> 	dns-nameservers 208.67.222.222 208.67.220.220

I think you are correct here. IIRC, I was using resolvconf initially
(while using my own ISP connection), but removed the package when I
stated to use opendns servers in my tomato firmware. Perhaps it is time
to reinstall the package.


> Please report the results either way.

I haven't still resolved what is the deal with Tomtom device appearing
as a network device. But my computer's networking is working fine with
dhcp. All I now need to do is to configure resolvconf to use my
specified opendns addresses.

Thanks for all the explanations and corrections.

Is there a GUI in KDE that allows do these kind of configurations,
something akin to Gnome's nm-applet?


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