[mythtv-users] HowTo avoid password nagging

[Nicolas Will]

On Sun, 2007-12-09 at 19:43 +0000, Nicolas Will wrote:
> hmm...
> 
> The problem with that statement is that network manager does
> absolutely
> no WPA on its own. It relies entirely on wpasupplicant for this.
> 
> So, if network manager works, wpasupplicant works.
> Then /etc/network/interfaces should work.

Let me rephrase this... only in a quite longer monologue.



NetworkManager is just a GUI. A clever piece of GUI, but a GUI
nevertheless.

NetworkManager will probe the network driver (a kernel module) through a
standard interface in order to access it (wext). It will get all sort of
info about the available networks, like ESSID names, BSSIDs, Crypto
types. It displays that list to you in the dropdown menu.

Once you select a network in that menu, NetworkManager will generate a
wpasupplicant config and pass it to wpasupplicant, wait for proper
authentication to happen (done by wpasupplicant through wext too) and
the cryptography to be setup (done by wpasupplicant through wext too),
then run a dhcp request for an IP address.

So, NetworkManager is just a graphical remote control for wext and
wpasupllicant.

NetworkManager is not a wireless device driver, it never talks directly
to device drivers. It does not do any authentication or cryptography by
itself. It uses wext and wpasupplicant.

wpasupplicant is not a device driver, it never talks directly to device
drivers. It uses wext.

This is why I am reaching the conclusion that if you can connect to you
network using NetworkManager, then wpasupplicant must be working.

As an aside... I you go to the NetworkManager dev list and complain
about it not working, the first thing you will be asked is about making
it work first manually using only wpasupplicant, and then provide the
wpasupplicant conf file you used.



Now, about what I was advising you to use.

I gave you a link to a document on how to configure
the /etc/network/interfaces file.

/usr/share/doc/wpasupplicant/README.modes.gz

This file is the basic Debian way of configuring network. NetworkManager
came later and had to adapt to it (needed to be adapted to it, really).

This file is in fact a configuration file for a bunch of scripts that
are run when the network is starting.

All the configuration items starting with wpa- will in fact be used in
order to generate a wpasupplicant configuration, which will be then used
by wpasupplicant itself.

So you can consider /etc/network/interfaces to be a manual and
text-based NetworkManager, only less automated.

/etc/network/interfaces works the same way, except that it never probes
anything by itself and needs a minimum information beforehand. It never
talks to the kernel driver, it just uses wpasupplicant.

/etc/network/interfaces will have the pre-shared key, it does not need
any keyring manager.



Moreover, the Ubuntu implementation of NetworkManager scans for
interfaces configured in /etc/network/interfaces when it starts. If any
interface is manually configured there, it will leave it as it is and
not manage it in any way, thus avoiding a conflict of interests.



<soap box>
As a gratuitous and pedantic remark I will say
that /etc/network/interfaces is the "only one true Debian way" of
configuring the network on a Debian/Ubuntu system. NetworkManager is
late-coming click'O'matic that still has issues.

Don't get me wrong, I'm a big fan of NetworkManager on my laptops, I
just think that it should be avoided on fixed systems, especially
server-like devices, like MythTV systems tend to be.
</soap box>




In conclusion...

If NetworkManager works, then wpasupplicant works.

If wpasupplicant works, then /etc/network/interfaces should work.

The device driver is irrelevant.



Those were my slightly inflated 2 cents, and I am hoping they will help.

Nico