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Re: Back to technical discussion? Yes! (was: network-manager as default? No!)


On Monday 04 April 2011, Sune Vuorela wrote:
> > I do not think that reading documentation before trying to achieve
> > something is that elitist. And in the case of wpa_supplicant, it is
> > definitely not dozens of pages. Basically, it is just
> >
> > man interfaces
> > man wpa_supplicant.conf
> > zless /usr/share/doc/wpasupplicant/README.Debian.gz
> I don't consider myself 'stupid user', but I haven't yet been able to
> put my laptop on wpa network without the use of network manager.

The most simple case, one static wlan definition, no roaming:


allow-hotplug wlan0
iface wlan0 inet dhcp
	wpa-ssid <whatever>
	wpa-psk <whatever>

Simple roaming, 2 example networks (with differing priorities) and 
catch-all for open networks, this allows automatic roaming between the
defined network setups:


allow-hotplug wlan0
iface wlan0 inet manual
	wpa-roam /etc/wpa_supplicant/wpa-roam.conf

iface home_network inet dhcp
iface my_work_net inet dhcp
iface default inet dhcp






proto, pairwise and group are not really mandatory, but avoid stepping 
down to WPA1 or TKIP, if another access point only offers that. psk can
be ASCII- (in quotes) or hexadecimal keys (64 characters). More complex
setups like IEEE8021X, certificates, TTLS/ PAP etc. can be configured 
just as well. /usr/share/doc/wpasupplicant/examples/ can help quite a 
lot for more exotic setups. ADSL/ PPPoE dial-in setups, in the absence 
of routers, aren't much more difficult.

What's so nice about ifupdown (and wpasupplicant integration)?
It simply works with minimal dependencies and can be configured through
your preferred {,cli-} editor, which is an important use case for me. 
It doesn't break on changing D-Bus interfaces and doesn't need 
functional X11/ D-Bus for configuration or operations, nor breaks ssh 
sessions during upgrades.

Besides not using netlink internally, ifupdown's biggest drawback in my
personal opinion is not reacting dynamically to changing connection
methods, like switching from wlan0 to eth0, if an ethernet cable gets 
temporarily connected - ifplugd can act as a bandaid here, but is not 
overly reliable (and possibly doesn't cover UMTS connections or other 
mobile connections either, but I'm not sure about this).

On the other hand n-m isn't an option for server or (quasi-) headless
systems at all, be it due to large dependency chains (there is no D-Bus
or X.org installed on my servers) or simply unreliable operations 
during remote upgrades (restarting the interface upon n-m upgrades).
While it's certainly a convenient configuration method for notebook 
users, who switch often between different connectivity methods (ADSL/ 
PPPoE, ethernet, wlan, PPP over bluetooth/ PAN, UMTS/ 3g, WiMAX/ 4g or
different VPN profiles). However for me personally, a "simple" and 
dependable ifupdown like solution, which can be configured/ operated
through the cli, and with minimal dependency chains is more important 
than a pretty GUI.

Maybe new solutions targetted at the embedded sector, like ConnMan or
the new netlink based network manager planned for OpenWrt, can fill
this void, but personally I doubt network-manager can (or at least 
will-) be adapted to work reliably for the afforementioned server like 
use cases.

	Stefan Lippers-Hollmann

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