no internet connection with Fedora16

Timothy Murphy gayleard at eircom.net
Sat Jan 14 15:11:00 UTC 2012


Tim wrote:

>>> It's there to deal with changing networks, such as my laptop being
>>> either wired or wireless, on any LAN, automatically.  And it does that
>>> fine, for me.  To force it into only dealing with WiFi would make it
>>> useless.
> 
> Timothy Murphy:
>> Do you mean that your ethernet and WiFi are on different LANs?
>> If they are, wouldn't it be simpler _not_ to use NM on the ethernet LAN?
> 
> I mean things like take the laptop home, it automatically joins my
> network.  Take it somewhere else, it automatically joins that network
> (well, once I've established credentials, it'll automatically join that
> network, now, and the next visit).  And at home I have a wireless
> network, but I could plug in the cable if I need to do something that
> way.

But would you plug in the ethernet cable anywhere else?

As it happens I do plug in my cable in two different locations
(in different countries).
As I said, I've had absolutely no problem in either place with this,
whether using NM or not using NM.
The computers ethernet MAC address is registered on both systems,
and I've actually used the same IP address in both places, for simplicity;
but I don't think that would have made any difference.

I haven't understood what problem, precisely, you would have
if you were not using NM?
 
> And Network Manager manages that, I just plug in, or get near enough,
> and connection just happens.  I don't have to fiddle around with
> bringing some network interface up on the command line, with any GUI, or
> any sort of list.  I don't have to change any settings to suit the
> different network, Network Manager has handled changes when the network
> came up (different DNS here, different IP there, etc.).
> 
>> I'm not sure what you mean.
>> How do you "customise your DHCP client"?
> 
> Well, in the olden days, it was done in /etc/dhclient.conf file.  Where,
> you added in overrides that your client should use instead of the
> information supplied by the server.  Such as use some other DNS server
> than it tells you to.

What difference would it make if you did name a different DNS server?

> Of course, one problem with that is that people kept on fiddling with
> their machine configuration, instead of setting up their DHCP server
> properly.  i.e. Put in working DNS server addresses into the DHCP
> server.
> 
> Nowadays it ought to be done through some Network Manager options, to
> customise the particular connection you're using.  Again, it's the case
> of configuring the network properly, rather than trying to bludgeon in
> settings at a lower level.

It may surprise you to learn that NM does not work for many people
in certain situations;
so any system that assumes NM is running is just going to cause problems.

>> NM doesn't work with 2 of my machines -
>> an EeePC and an old machine bought at Lidl.
>> It also doesn't work properly with Orinoco Classic Gold PCMCIA WiFi
>> cards. The network service works on all these.
> 
> I can't answer for that.  The same drivers are used.  It's just an
> automation manager that follows a set of rules about what to do.

Assuming "It" is NM, it makes certain assumptions 
about the facilities available on the WiFi card, 
assumptions that are not made by the network service.
In particular, NM seems to require (or used to require) 
that the card should support some kind of "scanning".

> It's
> worked on anything that I've thrown at it.  But then I have a working
> DHCP server on my LAN.  I'm not expecting an automation tool to work
> without the normal data used for automation.

The NM problems I have with a small number of machines and cards
don't have anything to do with dhcp.

>> In my opinion NM software is absurdly complicated,
>> largely because it is trying to do too much.
> 
> It's not doing very much at all.  Notice a network is available, apply
> suitable configuration to your network to use it.

I looked at the code some time ago
(in order to interpret some of the error messages it was throwing out)
and I found it very difficult to follow.
Admittedly I am not very good at reading code.

It seemed to me - though I might be wrong -
that the code had been subject to many modifications,
apparently by different hands.


-- 
Timothy Murphy  
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College Dublin




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