[arch-general] [arch-dev-public] network interface naming with systemd 197

[Sander Jansen]

On Mon, Jan 7, 2013 at 9:58 AM, Dave Reisner <d at falconindy.com> wrote:

> On Mon, Jan 07, 2013 at 09:35:45AM -0600, Leonid Isaev wrote:
> > On Mon, 07 Jan 2013 08:23:10 +0100
> > Andrea Scarpino <andrea at archlinux.org> wrote:
> >
> > > On Monday 07 January 2013 07:51:30 Allan McRae wrote:
> > > > Upstream decision...  vanilla packages should follow it.
> > >
> > > I agree with Allan. We don't use to change the default behavior. Ship
> it as
> > > default and add two lines on how to disable it.
> > >
> >
> > If I may chime in... regarding switching from MAC-based iface naming to
> > ID_NET_NAME_PATH-based naming. How exactly are these ID_NET_NAME_PATH
> > variables assigned?
> >
> > For instance, I have a box with 2 pci intel cards:
> > 1. DEVPATH=/devices/pci0000:00/0000:00:05.0/0000:02:00.0/net/elan0
> >    ID_NET_NAME_PATH=enp2s0f0
> > 2. DEVPATH=/devices/pci0000:00/0000:00:06.0/0000:03:00.0/net/elan1
> >    ID_NET_NAME_PATH=enp3s0f0
> >
> > Do I correctly understand that "enp?s0f0" is chosen based on a
> particular pci
> > slot the card is inserted in and will change if I choose to replug the
> cards?
>
> Yes, it's derived from the PCI path of the card in this case, and yes
> it'll change if you physically move the card. There's some examples of
> composed paths in udev source:
>
>
> http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n21
>
> If this is a concern to you, ID_NET_NAME_MAC is also available, which
> will always be the MAC from the hardware and should never be any
> possible faked address from the OS side.
>
> $ macchanger -m 12:34:56:78:90:ab eth0
>  Current MAC: de:ad:be:ef:00:01 (unknown)
>  Faked MAC:   12:34:56:78:90:ab (unknown)
>
> $ udevadm info -q property /sys/class/net/eth0 | grep ID_NET_NAME_MAC
>  ID_NET_NAME_MAC=enxdeadbeef01
>
> d
>

So I'm guessing for users of NetworkManager there shouldn't be any change.
And people using 'systemctl enable dhcpcd at eth0' will have to change the
device name? Can this be done before the reboot (for headless systems, so
the network will be come up on next reboot) ?

Sander