Re: I probably have the wrong idea for NetworkManager...

[Dan Williams <dcbw redhat com>]

On Fri, 2008-05-30 at 16:19 -0400, Rick Beldin wrote:
> Ubuntu 8.04

Ok; that means NM 0.6.6 which is somewhat limited in it's capability to
control more complex connections.  0.7 is better here but Ubuntu isn't
shipping it since it's not entirely released yet.  We've gotten pretty
good results so far with 0.7 prerelease versions in Fedora 8 and Fedora
9 over the past 9 months though.

> I'll have to admit that I am rather old school when it comes to administering
> my machines.   I usually like to take a more active approach than
> letting a daemon make decisions for me.   I used to hack on
> /etc/network/interfaces and /etc/resolv.conf to get what I wanted
> done, and in some ways I am missing that level of control...
> 
> I have an HP laptop with a wired and a wireless interface.   My
> network usage falls into three models:
> 
> - wireless,  no VPN, roaming
> - wired, no wireless (in the office) DHCP on wired
> - wireless, VPN, dhcp, no wired (tun0 interface created)
> 
> I run into several issues with NetworkManager:
> 
> - if I have been working at home, (wireless, WEP, VPN) and transition to
>   the office,  I have to manually enable the wired interface.

In the Ubuntu network control panel, have you made the wired device
"roaming" or "manual" mode?  When it's in Manual mode, it's hidden from
NM due to custom Ubuntu patches.

What _should_ happen is that when you plug the wired cable into your
laptop, NM will tear down the wireless connection and bring up the wired
connection using DHCP as you've specified.  But if you've put your
device in "manual" mode in ubuntu, then that's not to happen because
you've chosen to control the device manually.

> - if I have been working in the office (wired, no VPN) and come home,
>   I generally have to fiddle with enabling/disabling wireless and wired
>   interfaces until I get a DHCP address from the wireless router.  I
>   sometimes have to kill dhclient and clear out /var/lib/dhcp3 in order
>   for NetworkManager to realize it has to go get a new ip.  The
>   interface will be 'up' but no.  No errors from dhcp on router.

Sounds like a flaky driver isn't associating to the AP.  What wireless
card do you have?  Can you post some logs from /var/log/daemons to show
what NM is doing during this time?  What sort of wifi configuration do
you have at home?

> - if am working with the VPN (tun0) wireless and the little checkbox
>   is ON next to the wired interface, I am *assured* that my connection
>   will drop periodically.  Usually 5-10 minutes.  If I manage to get
> NetworkManager to leave off the little checkbox, then it will stay up
> indefinitely.

That also sounds like bad drivers are telling NetworkManager that the AP
has disconnected you.  What wireless card do you have again?

> I've tried setting up profiles for this and this sometimes works.  I
> still have to 'bounce' between profiles at time to get it to trigger
> dhclient properly.   I typically NEVER suspend and resume - these are
> cold boots.

Hmm, NM wouldn't do "profiles" for your use-cases (0.6.x saves configs
for wireless networks but not wired) so that's probably something
Ubuntu-specific.

> What is strange is if I revert to manual management of
> /etc/network/interfaces, I get a high level of stability - switching
> between wired and wireless is swift and certain.   I can control
> whether dhcp runs or not on the wired interface.

Right, because after configuring the interface, the tools exit and
nothing is aware of any changes to the network situation, like cables
being plugged in, the wifi AP going away, etc.  NM is set up to
dynamically handle these sorts of events that manual control never can,
but NM also depends on drivers to not suck and unfortunately many do...

> All this leads me to think that I am not using this in the right way.
> I think my needs are:
> 
> - if I am wired, I don't care about the wireless interface

Right, and if you're plugged into the wired interface, NM 0.6.6 won't
connect the wireless interface.  So this should work.

> - if I am wireless, I don't want the wired interface to even be probed

And if you don't have a cable plugged in, NM shouldn't be bringing up
the wired interface, so this should also already work.

If both your devices are set to be managed by NetworkManager, this
should result in the behavior you want already, so there must be a bug
somewhere either in NM or drivers.

Dan