CentOS - Dec 2014 - NetworkManager fights with DHCP-only backup NIC

On Dec 1, 2014, at 10:27 PM, Rob Kampen <rkampen at reaching-clients.com>
wrote:
> Have you put
> NM_CONTROLLED="no"
> in the ifcfg-eth0 script?
How is that better than

    systemctl stop NetworkManager
    systemctl disable NetworkManager

Again, I?m not really after a way to make this work without NetworkManager. 
We?ve already got that.  What I want is a way to tell NM to obey the MAC
binding.  This configuration *here* goes with that MAC chip *there*.

Given that, we don?t need to disable NetworkManager.

On Tue, Dec 2, 2014 at 2:26 PM, Warren Young <wyml at etr-usa.com>
wrote:
> On Dec 1, 2014, at 10:27 PM, Rob Kampen <rkampen at
reaching-clients.com> wrote:
>
>> Have you put
>> NM_CONTROLLED="no"
>> in the ifcfg-eth0 script?
>
> How is that better than
>
>     systemctl stop NetworkManager
>     systemctl disable NetworkManager
>
> Again, I?m not really after a way to make this work without NetworkManager.
We?ve already got that.  What I want is a way to tell NM to obey the MAC
binding.  This configuration *here* goes with that MAC chip *there*.
>
> Given that, we don?t need to disable NetworkManager.
What part of the breakage that NetworkManager does is good for a
wired, static-addressed server?    But, in your scenario where both
nics are plugged in and your only problem is the non-working gateway
IP you should be able to ssh to some other box on the working network,
then over to the new ones DHCP address.  The gateway won't matter if
both ends are on the same subnet.

-- 
    Les Mikesell
      lesmikesell at gmail.com

On Dec 2, 2014, at 1:36 PM, Les Mikesell <lesmikesell at gmail.com> wrote:
> On Tue, Dec 2, 2014 at 2:26 PM, Warren Young <wyml at etr-usa.com>
wrote:
>> Again, I?m not really after a way to make this work without
NetworkManager.
> 
> What part of the breakage that NetworkManager does is good for a
> wired, static-addressed server?
If you disable NM, the network configuration GUI stops working in EL7.  (I
didn?t do much with EL6, but I thought its GUI had a fall-back for the non-NM
case.)

We don?t need this GUI, but our semi-technical customers sometimes do.  It can
be the difference between rolling a truck to a remote site vs letting the
on-site people take care of the problem.
> you should be able to ssh to some other box on the working network,
I did mention that these sites rarely have local staff who know Linux.  You can
correctly infer from that there *are* no other SSH servers, just ours.

These are K-12 schools, for the most part.  They often don?t have technical
staff on-site at all.  We have to schedule time with overworked district-level
staff who often only know Windows to get anything at this level done.

We?ve built up nasty hacks to solve this before; VPN -> RDP -> PuTTY ->
Linux server, for instance.  Getting protective network admins to allow all this
can chew up weeks of time.

It?s far, far better if the Linux box just phones home with the info we need to
fix it.  It can cut a 4-week phone tag game down to 15 minutes.