CentOS - Jun 2021 - Static configuration: prevent /etc/resolv.conf from being overwritten on first reboot

Hi,

Here's something that's puzzling me.

Starting from a minimal installation of CentOS 7, network configuration is DHCP.

I'm launching nmtui to define a static configuration.

I'm providing the IP address as well as the gateway, but no DNS server.

I'm quitting nmtui and I'm editing /etc/resolv.conf to provide my DNS
server:

# /etc/resolv.conf
nameserver 192.168.0.254

I reboot my server, and I don't know why, but my /etc/resolv.conf has been
overwritten:

# Generated by NetworkManager

So I edit this file again:

# /etc/resolv.conf
nameserver 192.168.0.254

And starting from here, it works, meaning /etc/resolv.conf is not overwritten
on subsequent reboots.

Q: how can I prevent /etc/resolv.conf from being overwritten on the initial
reboot? I vaguely remember having to kill some process before editing it, but
unfortunately I don't remember which one.

Cheers,

Niki
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Nicolas Kovacs <info at microlinux.fr> wrote:
> 
> Q: how can I prevent /etc/resolv.conf from being overwritten on the initial
> reboot? I vaguely remember having to kill some process before editing it,
but
> unfortunately I don't remember which one.
One way to do this is to create the file /etc/dhcp/dhclient-enter-hooks that
contains:

 make_resolv_conf(){
        :
 }

Or, add the line 'PEERDNS=no' to the matching
/etc/sysconfig/network-scripts/ifcfg-XXXX file

James Pearson

On 6/7/21 1:32 AM, Nicolas Kovacs wrote:
> # Generated by NetworkManager
...
> Q: how can I prevent /etc/resolv.conf from being overwritten on the initial
> reboot?

Edit /etc/NetworkManager/NetworkManager.conf:

[main]
dns=none