-----Original Message----- From: CentOS [mailto:centos-bounces@centos.org] On Behalf Of Scott Robbins Sent: Friday, January 13, 2017 8:31 AM To: CentOS mailing list Subject: Re: [CentOS] Unable to edit resolv.conf

On Fri, Jan 13, 2017 at 07:49:48AM -0500, TE Dukes wrote:

Hello,

I changed ISPs and need to update name servers in resolv.conf.

I have tried nano, gedit, Webmin, system-config-network and it won't allow me to make the changes.

I have Network Manager turned off and when I enable it , eth0 and eth1 have no entries.

I enabled it, added the connections, but still no changes.

I'm stuck

I know that in Fedora, resolv.conf is now some symlink to a NetworkManager file (I forget where).

Try doing ls -l /etc/resolv.conf, and see if that's the case in CentOS-7 as well. (I don't use NM, so I'm not sure what the case is with it, as the machine I'm using had that change made, if it was needed, long ago. :) )

If it does turn out to be a symlink, copy its information, if you need it, then delete the file, then recreate it.

Hope this helps, but I'm not sure. It is a working solution in Fedora.

Hi, thanks, it does not show it being a sym link.

On 01/13/2017 05:50 AM, Albert McCann wrote:

...

-----Original Message----- From: CentOS [mailto:centos-bounces@centos.org] On Behalf Of TE Dukes Sent: Friday, January 13, 2017 7:50 AM To: 'CentOS mailing list' centos@centos.org Subject: [CentOS] Unable to edit resolv.conf

I changed ISPs and need to update name servers in resolv.conf.

I have tried nano, gedit, Webmin, system-config-network and it won't allow me to make the changes.

I have Network Manager turned off and when I enable it , eth0 and eth1 have no entries.

I enabled it, added the connections, but still no changes.

You haven't done what I've done intentionally, flag /etc/resolv.conf immutable with "chattr +i /etc/resolv.conf" have you?

I do this to keep Network Manager and other busybodies from making unwanted / unneeded changes.

I've tried to figure out how to get Network Manager to leave various configuration files alone and just gave up - resorting to cron job running as root every minute fixing them if they have been modified.

I wish there was better documentation on how Network Manager is configured because I can't figure out how to get it to behave.

My home router - the caching nameserver it uses doesn't enforce DNSSEC and crashes about once a week, requiring a restart. So I just don't use it except for my phone and tablet, and just run unbound on my local machines, but Network Manager keeps trying to use the nameserver assigned by the router DHCP (which is the router) and other than a once a minute cron job, can't figure out how to tell Network Manager to ignore the nameserver setting.

-----Original Message----- From: CentOS [mailto:centos-bounces@centos.org] On Behalf Of Barry Brimer Sent: Friday, January 13, 2017 9:42 AM To: CentOS mailing list Subject: Re: [CentOS] Unable to edit resolv.conf

...

...

I changed ISPs and need to update name servers in resolv.conf.

I have tried nano, gedit, Webmin, system-config-network and it won't allow me to make the changes.

Have you tried adding PEERDNS=no to your ifcfg-device file? If that doesn't work, you might be able to use NM_CONTROLLED=no as well.

Thanks,

Giving it a try now.

On 01/13/2017 07:00 AM, Albert McCann wrote:

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-----Original Message----- From: CentOS [mailto:centos-bounces@centos.org] On Behalf Of Alice Wonder Sent: Friday, January 13, 2017 8:59 AM To: centos@centos.org Subject: Re: [CentOS] Unable to edit resolv.conf

I've tried to figure out how to get Network Manager to leave various configuration files alone and just gave up - resorting to cron job running as root every minute fixing them if they have been modified.

...

...

My home router - the caching nameserver it uses doesn't enforce DNSSEC and crashes about once a week, requiring a restart. So I just don't use it except for my phone and tablet, and just run unbound on my local machines, but Network Manager keeps trying to use the nameserver assigned by the router DHCP (which is the router) and other than a once a minute cron job, can't figure out how to tell Network Manager to ignore the nameserver setting.

Have you tried setting PEERDNS=no in the /etc/sysconfig/network-scripts/ifcfg-<X> script(s)?

I have an ancient note here from 5.x days with the above fix.

That might work on my desktop but I don't think it would work on my laptop where it seems to create new network scripts for every wifi network it connects to.

On 01/13/2017 07:07 AM, TE Dukes wrote:

I may have. If so, is there a way to undo it?

You can determine whether you've set the file's immutable attribute using "lsattr". You can remove it using "chattr -i"

-----Original Message----- From: CentOS [mailto:centos-bounces@centos.org] On Behalf Of Gordon Messmer Sent: Friday, January 13, 2017 10:10 AM To: CentOS mailing list Subject: Re: [CentOS] Unable to edit resolv.conf

On 01/13/2017 04:49 AM, TE Dukes wrote:

I changed ISPs and need to update name servers in resolv.conf.

...

I have Network Manager turned off and when I enable it , eth0 and eth1 have no entries. I enabled it, added the connections, but still no

changes.

If you want to use NetworkManager, edit /etc/NetworkManager/NetworkManager.conf and add "dns=none" in the main section:

[main] plugins=ifcfg-rh dns=none

If you don't want to use NetworkManager, then set PEERDNS=no and remove any DNS1, DNS2, etc settings in /etc/sysconfig/network-scripts/ifcfg-* _______________________________________________

Thanks!

I made the change in ifcfg-eth0 and eth1 to PERRDNS=no.

Then I did a really dumb thing -- I did a service network stop instead of restart.

I'm done till I get back home this evening.

:-(