Re: Diskless clients and NetworkManager

[Dan Williams <dcbw redhat com>]

On Thu, 2009-04-30 at 17:17 +0200, David Sundqvist wrote:
> Quoting Marc Herbert <Marc Herbert gmail com>:
> > There seems to be something fundamentally wrong in this no-connection/
> > /offline thing. Since NM can be configured to manage _not all_
> > interfaces (including none at all) then why are some applications
> > wrongly assuming NM is always managing the entire network
> > configuration? This seems to be where the bug lies and should be
> > fixed.
> 
> Perhaps. Taking a quick look at the NM project webpage, it's not  
> really that farfetched: "Using the awesome power and flexibility of  
> dbus and hal, NetworkManager provides facilities for other  
> applications like browsers, email clients, or system services to be  
> aware of the network's state and adjust their operation accordingly."

Some of that is hyperbole, but for the most part its correct.  NM aims
to give applications a good idea about the state of the network, but of
course that only works if NM *knows* the state of the network.  Some
users do not allow NM to do that, and sometimes there are bugs in NM
that prevent users from allowing NM to do that.

> That certainly could sound fairly authoritative to a presumptive  
> software developer, so I can understand why they make that assumption.
> 
> > Is there other buggy applications that people should be afraid of
> > besides firefox?
> 
> Lots. And I'd expect them to increase, as an app that could give an  
> authoritative statement on connectivity, as far as it's possible,  
> would certainly be useful. As I see it there are basically two  
> possible solutions:
> 
> 1) Let NetworkManager have some form of 'read-only' interfaces or  
> forced mode setting, in the cases where it can't appropriately manage  
> the interface. I found some threads relating to diskless clients  
> suggesting that NM could not be entirely trusted to keep its hands off  
> the interface so I'd be hesitant to let it manage the interface  
> providing root/swap disk access.

The idea is to extend NM to handle these cases.

> 2) Disabuse application developers of the notion that NetworkManager  
> has an accurate status. The first step of which would be to change the  
> project page a bit to say "be aware of NM's perhaps not entirely  
> accurate idea of the network's state"

Or the better solution: lets fix NetworkManager to handle the cases that
people currently have that NetworkManager does not support.  The only
reason it can't handle some the use-cases are because people have not
stepped up to the plate to help out.  Those of us working on it full
time only have so much time in the day to fix these things, which is why
stuff like Bluetooth, bridging, IPv6, etc aren't done yet.

Until that's done though, if there is some case (like diskless
workstation) where NM cannot handle the primary internet connection, you
probably want to turn NM off for now.

Dan