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CentOS 7.5 (1804) and NetworkManager

Hi,

I'm running CentOS on all kinds of setups: servers, workstations,
desktops and laptops.

Up until now, I'm only using NetworkManager on laptops, since it makes
sense to use it there. On servers and desktop clients, I usually remove
it and configure the network "traditionally" by simply editing
/etc/sysconfig/network-scripts/ifcfg-whatever, /etc/resolv.conf,
/etc/hosts, /etc/hostname and /etc/sysconfig/network. Running
NetworkManager on anything else than a laptop has never made any sense
to me, since it's basically an extra layer of abstraction.

With the latest update, the removal of NetworkManager on a desktop
client isn't possible anymore, since 'yum remove NetworkManager' also
tries to remove 'gdm', and disabling it on startup spews back all sorts
of errors.

If you folks at Red Hat are reading this, I have one question: WHY ?

Niki Kovacs

Comments

Re: CentOS 7.5 (1804) and NetworkManager

By Jonathan Billings at 05/15/2018 - 11:01

On Tue, May 15, 2018 at 12:40:06PM +0200, Nicolas Kovacs wrote:
On a server, who cares if you remove GDM, you aren't running X
anyway. If you are, it's a workstation really, and the following
applies.

On a Workstation, it's part of the GNOME environment. I'm not
surprised it is required if you want GNOME. If you don't want NM, I
suggest using something other than GNOME (which requires gdm on
workstations, otherwise you don't get a screen lock). Workstations
need the ability to manage things like VPNs and ephemeral network
devices like bluetooth, so you'll need a GUI interface, which talks
with NetworkManager.

However, I've always used NM on servers in C7. The old 'network'
service tries once to set up the network when the system boots, and
doesn't handle network outages well at all. With NM, it can detect
media coming up and restore networking. It can be set up with
dispatchers to run commands when the network goes up and down (fix the
clock and restart remote syslog, for example).

A lot of these are also the case for Workstations (maybe even more
so). You need something to be able to handle a changing network
environment during the daily utilization of a system.

NM in CentOS 7 is a different beast than it was in C6. If you were
burned by NM in C6, give it a try in C7, you might find it
acceptable.

Re: CentOS 7.5 (1804) and NetworkManager

By Niki Kovacs at 05/15/2018 - 11:05

Le 15/05/2018 à 17:01, Jonathan Billings a écrit :
On servers, I always install all NetworkManager-related packages.

My question was about my workstation with KDE/GDM. Here's how I did
things until now, and apparently I can't do that anymore:

<a href="https://blog.microlinux.fr/poste-de-travail-centos-7/#reseau-pc" title="https://blog.microlinux.fr/poste-de-travail-centos-7/#reseau-pc">https://blog.microlinux.fr/poste-de-travail-centos-7/#reseau-pc</a>

Niki

Re: CentOS 7.5 (1804) and NetworkManager

By Stephen John Smoogen at 05/15/2018 - 08:36

On 15 May 2018 at 06:40, Nicolas Kovacs < ... at microlinux dot fr> wrote:
The latest RHEL releases are getting rebased with newer Gnome and
other components. Those are more interlinked with NetworkManager and
other helper tools to work towards a less bag of potatoes and other
junk approach.

This isn't to say this is the right thing. It is just a statement of
why things are and where they seem to be going.

Re: CentOS 7.5 (1804) and NetworkManager

By Gianluca Cecchi at 05/15/2018 - 07:19

Disclosure:
I'm not a folk at Red Hat ;-)

In CentOS / Fedora I simply disable NetworkManager service and put into
ifcfg-xxx (eg ifcfg-eth0) the line

NM_CONTROLLED=no

The network service is enabled by default, so this should be sufficient to
keep NetworkManager installed but not inerfering with your classic network
configuration.

On a just updated c7test vm

[root@c7test ~]# uptime
13:19:51 up 2 min, 1 user, load average: 0.10, 0.15, 0.07
[root@c7test ~]#

[root@c7test ~]# cat /etc/centos-release
CentOS Linux release 7.5.1804 (Core)
[root@c7test ~]#

[root@c7test ~]# systemctl status NetworkManager
● NetworkManager.service - Network Manager
Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service;
disabled; vendor preset: enabled)
Active: inactive (dead)
Docs: man:NetworkManager(8)

[root@c7test ~]# systemctl status network -l
● network.service - LSB: Bring up/down networking
Loaded: loaded (/etc/rc.d/init.d/network; bad; vendor preset: disabled)
Active: active (exited) since Tue 2018-05-15 13:17:27 CEST; 15s ago
Docs: man:systemd-sysv-generator(8)
Process: 700 ExecStart=/etc/rc.d/init.d/network start (code=exited,
status=0/SUCCESS)

May 15 13:17:21 c7test.mydomain systemd[1]: Starting LSB: Bring up/down
networking...
May 15 13:17:23 c7test.mydomain network[700]: Bringing up loopback
interface: [ OK ]
May 15 13:17:27 c7test.mydomain NET[1001]:
/etc/sysconfig/network-scripts/ifup-post : updated /etc/resolv.conf
May 15 13:17:27 c7test.mydomain network[700]: Bringing up interface eth0:
[ OK ]
May 15 13:17:27 c7test.mydomain systemd[1]: Started LSB: Bring up/down
networking.

[root@c7test ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group
default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state
UP group default qlen 1000
link/ether 00:1a:4a:16:01:00 brd ff:ff:ff:ff:ff:ff
inet 10.4.4.33/24 brd 10.4.4.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::21a:4aff:fe16:100/64 scope link
valid_lft forever preferred_lft forever
[root@c7test ~]#

HOIH,
Gianluca

Re: CentOS 7.5 (1804) and NetworkManager

By Niki Kovacs at 05/16/2018 - 11:00

Le 15/05/2018 à 13:19, Gianluca Cecchi a écrit :
OK, I played around with this quite a bit. Here's my findings.

1. On my KDE workstation, NetworkManager cannot be removed, because this
would also remove GDM.

2. NetworkManager can be disabled though. On the other hand, I get a big
fat warning on startup for "NetworkManager dependency not met".

3. For now, the KISS approach seems to be to just leave NetworkManager
installed and running, and to configure network-scripts/ifcfg-enp0s3
like this:

DEVICE=enp0s3
TYPE=Ethernet
ONBOOT=yes
BOOTPROTO=dhcp
NM_CONTROLLED=no

Cheers & thanks for your numerous suggestions.

Niki