Re: Annoying NetworkManager "feature"

[Dan Williams <dcbw redhat com>]

On Sat, 2009-08-29 at 12:33 -0400, Gene Czarcinski wrote:
> I have tried to simplify things but may still be unclear ... sorry.  If you 
> would prefer, I can put all of this info in a bugzilla report or continue here 
> on this mailing list.
> 
> On Wednesday 26 August 2009 12:59:44 Dan Williams wrote:
> > On Mon, 2009-08-24 at 13:08 -0400, Gene Czarcinski wrote:
> > > I like a lot about how NetworkManager works.  I especially like the way
> > > it handles wireless connects.
> > >
> > > However, there is a NetworkManager "feature" that is extremely annoying:
> > > creating new/additional device entries in its list of devices ...
> > > sometimes one or more additional entries with the same name and sometimes
> > > "Auto eth_" entries.
> >
> > Which new/additional device entries and what are their names?  When this
> > happens, can you run 'nm-tool' for me and paste the output in here?
> 
> more below
> 
> >
> > The "Auto eth_" entries are there so that you can connect to *something*
> > by clicking on it even when there's configuration defined.  Otherwise,
> > you'd have nothing in the menu and no way to connect the device.  There
> > are a few corner cases where more than one could appear, but I haven't
> > seen those in quite a while.
> 
> OK, I am not sure your statement as written was your intent.  I can understand 
> creating "Auto eth_" if no ifcfg-eth_ file exists, but why do this if the file 
> does exist ... and then, not necessarily consistently (see below).

Sorry, that should read "when there's _no_ configuration defined".

> >
> > > This has become especially annoying with a qemu-kvm guest where on of the
> > > NICs needs to have "Use this entry for network connections only on its
> > > network" checked ... new entries are created when NetworkManager starts
> > > which do not have the check.
> > >
> > > If there a way to disable this feature? [new/additional entries]
> >
> > Do you have backing system connections for any of these devices?
> > Basically, a fake "auto" connection will be shown for any device that
> > doesn't already have a connection defined either in GConf or via
> > system-settings (/etc/network/interfaces for Debian/Ubuntu, ifcfg for
> > suse/fedora, and /etc/NetworkManager/system-connections for all distros
> > depending on the plugin that's been enabled
> > in /etc/NetworkManager/nm-system-settings.conf).
> 
> See comment above.  
> 
> I have sometimes seen ~.gconf/ entries but not all the time.  What are the 
> conditions when this is done?

By default, creating a connection in the applet or connection editor
creates a GConf "user" connection, not a system connection.  Creating a
system connection is only done when the "Available to all users" box
gets checked in the connection editor, and the Apply button is clicked.

> I have never seen anything in /etc/Network?manager/system-connections/.  
> Again, when is this suppose to be used?

This will happen when the keyfile plugin is enabled
in /etc/NetworkManager/nm-system-settings.conf and the "Available to all
users" button gets checked in the connection editor, and Apply gets
clicked.

The first write-capable plugin on the plugins= line wins, so on Fedora,
that's 'ifcfg-fedora'.  Thus if you have "plugins=ifcfg-fedora,keyfile",
the ifcfg-fedora plugin will write the file out, not keyfile.

Other distros typically have keyfile as the only write-capable plugin
(since only ifcfg-fedora and keyfile are write-capable anyway, and it's
pointless to use ifcfg-fedora on Debian), and thus keyfile gets the
connection write request there no matter where it's at on the plugins=
line.

> -------------
> I have seen the problems described here on real hardware.  However, I am 
> currently using qemu-kvm to run guest virtuals and it is really easy to 
> add/remove NICs.  Many of my problems have occurred on a Fedora 11 system 
> running virt-preview packages (F12 alpha/rawhide packages built for F11).  
> However, to simplify things, the info below and most of my testing for this is 
> done on a x86_64 F11 host running F11 qemu-kvm with a x86_64 F11 guest.  
> NetworkManager is running on the guest.  The host does not use NetworkManager 
> because I have a bridged NIC (br0).
> 
> The interfaces on the guest all use "virtio" devices for the NICs.  Also, they 
> all use dhcp.  Default/NAT network is 192.168.122.0/24; Private network is 
> 192.168.217.0/24
> 
> OK, here is the senario ---
> 
> 1. Built fresh x86_64 F11 guest with all updates as of 27 August (Friday) and 
> a "standard" (default network) NIC which supports NAT on a "virtio" device.  
> System installs and boots up fine ... network works and NetworkManager running.  
> I can access the Internet.
> 
> 2. Shut the guest down and install a new NIC for a "private" network (similar 
> to "default" but no NAT, no forwarding, different IP numbers).  Screw things up 
> and accidentally delete the NAT NIC ... delete all NICs ... create a new NAT 
> NIC.  Reboot.
> 
> 3.  System boots up in single user mode ... disable autostart of network and 
> NetworkManager.  Looking at /proc/sys/net/ipv4/conf/, I now have "eth1" 
> instead of "eth0" although there is only one NIC and it is the same "type", 
> etc. [BTW, what in the world keeps track of these ... where is that 
> information kept???] ... telinit 5 ... use system-config-network to delete the 

I believe when using this it's the *host* that keeps track of how many
NICs you have created and sets them when KVM/QEMU start.  Note that
'udev' tries to ensure consistent naming, and will match up MAC
addresses with device names.  So if you change the MAC address or add a
different NIC with a different MAC address, your device name will
change.  See /etc/udev/rules.d/70-persistent-net.rules inside your VM.

> "eth0" definition and create a new "eth1" (System eth1) definition ... start 
> network ... it works ... stop network, start Network Manager ... it works 
> using "System eth1" (no extras).
> 
> 4.  Shut the guest down and install a 2nd NIC on the "private" network. Boot 
> (autostart network and NetworkManager disabled).  Use system-config-network to 
> define the eth2 configuration but mark it NOT NetworkManager managed.  Start 
> NetworkManager (System eth1 comes up).  Using system-config-network ,enable 
> NetworkManager ... NetworkManager brings up eth2 ... check NetworkManager 
> devices: System eth1, System eth2, Auto eth2 .. using System eth1 and System 
> eth2. Output of nm-tool:

At that point where you still have "Auto eth2", can you grab the output
of "gconftool-2 --dump /system/networking/connections" for me?

Dan


> ------------
> NetworkManager Tool
> 
> State: connected
> 
> - Device: eth2  [System eth2] 
> --------------------------------------------------
>   Type:              Wired
>   Driver:            virtio_net
>   State:             connected
>   Default:           yes
>   HW Address:        54:52:00:0D:85:BA
> 
>   Capabilities:
>     Carrier Detect:  yes
> 
>   Wired Properties
>     Carrier:         on
> 
>   IPv4 Settings:
>     Address:         192.168.217.151
>     Prefix:          24 (255.255.255.0)
>     Gateway:         192.168.217.1
> 
>     DNS:             192.168.217.1
> 
> 
> - Device: eth1  [System eth1] 
> --------------------------------------------------
>   Type:              Wired
>   Driver:            virtio_net
>   State:             connected
>   Default:           no
>   HW Address:        54:52:00:60:A8:F4
> 
>   Capabilities:
>     Carrier Detect:  yes
> 
>   Wired Properties
>     Carrier:         on
> 
>   IPv4 Settings:
>     Address:         192.168.122.162
>     Prefix:          24 (255.255.255.0)
>     Gateway:         192.168.122.1
> 
>     DNS:             192.168.122.1
> 
> ----------
> 
> 5.  Shutdown Networkmanager but do not reboot.  Hours later, start 
> NetwokrManager ... same NM devices but this time using System eth1 and Auto 
> eth2.  Output of nmtool:
> -------------
> NetworkManager Tool
> 
> State: connected
> 
> - Device: eth2  [Auto eth2] 
> ----------------------------------------------------
>   Type:              Wired
>   Driver:            virtio_net
>   State:             connected
>   Default:           yes
>   HW Address:        54:52:00:0D:85:BA
> 
>   Capabilities:
>     Carrier Detect:  yes
> 
>   Wired Properties
>     Carrier:         on
> 
>   IPv4 Settings:
>     Address:         192.168.217.151
>     Prefix:          24 (255.255.255.0)
>     Gateway:         192.168.217.1
> 
>     DNS:             192.168.217.1
> 
> 
> - Device: eth1  [System eth1] 
> --------------------------------------------------
>   Type:              Wired
>   Driver:            virtio_net
>   State:             connected
>   Default:           no
>   HW Address:        54:52:00:60:A8:F4
> 
>   Capabilities:
>     Carrier Detect:  yes
> 
>   Wired Properties
>     Carrier:         on
> 
>   IPv4 Settings:
>     Address:         192.168.122.162
>     Prefix:          24 (255.255.255.0)
>     Gateway:         192.168.122.1
> 
>     DNS:             192.168.122.1
> ---------------
> 
> Why the change?  I have no idea.
> 
> 6. Check routing ... default is 192.168.217.1 which is wrong!  Tried checking 
> the "Use only" route checkbox but no effect and does not persist when re-
> edited!  Tried GATEWAY= and GATEWAYDEV= in /etc/sysconfig/network but this has 
> no effect.
> 
> 7. Note, I just noticed that I now have a "ifcfg-Auto eth2" file which I have 
> never seen before.  Stop NM. Use s-c-n to delete "Auto eth2" interface.  
> Restart NM ... ok even if default route still screwed up.
> 
> 8.  Reboot.  Start NM.  Only System eth1 brought up.  System eth2 is marked 
> NetworkManager=yes but is not started???
> 
> Enough for now.
> 
> Gene
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