Re: Ethernet trouble

[David Wright <deblis@lionunicorn.co.uk>]

On Fri 31 Jan 2020 at 14:31:56 (-0700), ghe wrote:
> On 1/31/20 11:31 AM, Bob Weber wrote:
> 
> > I just ran a test on a VM that I installed last week so it is pretty
> > much up to date.  I ran the command "ip a" which gave me the current
> > undesirable name "enp1s0" and MAC address.
> 
> Check.
> 
> > First I created  /etc/systemd/network/10-eth0.link using the MAC address
> > and the name eth0.  
> 
> Check. (changed the MAC in your cat of the link file and changed the
> name in the interfaces file)
> 
> Rebooted and:
> 
> Jan 31 12:37:56 sbox systemd[1]: Starting Raise network interfaces...
> Jan 31 12:37:56 sbox ifup[2147]: ifup: unknown interface enp7s0
> Jan 31 12:37:56 sbox systemd[1]: networking.service: Main process
> exited, code=exited, status=1/FAILURE
> Jan 31 12:37:56 sbox systemd[1]: networking.service: Failed with result
> 'exit-code'.
> Jan 31 12:37:56 sbox systemd[1]: Failed to start Raise network interfaces.
> 
> To the best of my knowledge, there is no enp7s0 anymore. Where does:
> 
> [    2.445808] e1000e 0000:07:00.0 enp7s0: renamed from eth0
> 
> happen? (dmesg | egrep enp)
> 
> Then there's another line:
> 
> [   12.130525] e1000e 0000:07:00.0 eth0: renamed from enp7s0
> 
> That should have put eth0 back. Current guess is that sometime between
> 2.44 and 12.13, somebody tried to bring up the network interfaces and
> failed.
> 
> So in my current config, eth0 gets changed to enp7s0, ifup is called to
> bring up enp7s0, ifup fails because enp7s0 doesn't exist in the
> interfaces file, then enp7s0 gets changed back to eth0. As a programmer,
> I'm quite used to flaws in software, but lordie...

Assuming you followed Bob Weber, do you still have a symlink, ie,
link -s /dev/null /etc/systemd/network/99-Default.link
in place? What happens if you boot without it?

> And systemd is calling ifup? Which relies on the old interfaces file,
> and systemd relies on additional interface config file(s)?
> 
> After the boot, 'ifup eth0' by hand brings up the interface and ifconfig
> shows it active and with the right name and IP. (So does ip a -- I keep
> using ifconfig because that's what's in my scripts and it's what I'm
> used to.)

I really would avoid changing the interface name back to the one
the kernel chose, or any string that the kernel *might* choose;
ie, be original.

Cheers,
David.