CentOS - Jan 2017 - Unable to edit resolv.conf

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

TIA

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.

-- 
Scott Robbins
PGP keyID EB3467D6
( 1B48 077D 66F6 9DB0 FDC2 A409 FA54 EB34 67D6 )
gpg --keyserver pgp.mit.edu --recv-keys EB3467D6

> -----Original Message-----
> From: CentOS [mailto:centos-bounces at centos.org] On Behalf Of TE Dukes
> Sent: Friday, January 13, 2017 7:50 AM
> To: 'CentOS mailing list' <centos at 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.

Al
--
Evidence of a dissolute computer.

On 01/13/2017 05:50 AM, Albert McCann wrote:
>> -----Original Message-----
>> From: CentOS [mailto:centos-bounces at centos.org] On Behalf Of TE
Dukes
>> Sent: Friday, January 13, 2017 7:50 AM
>> To: 'CentOS mailing list' <centos at 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.

Hi,

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

Selinux enforcing mode activated?


 best regards
---
Michael Schumacher

-----Original Message-----
From: CentOS [mailto:centos-bounces at 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.

-----Original Message-----
From: CentOS [mailto:centos-bounces at centos.org] On Behalf Of Albert McCann
Sent: Friday, January 13, 2017 8:51 AM
To: 'CentOS mailing list'
Subject: Re: [CentOS] Unable to edit resolv.conf
> -----Original Message-----
> From: CentOS [mailto:centos-bounces at centos.org] On Behalf Of TE Dukes
> Sent: Friday, January 13, 2017 7:50 AM
> To: 'CentOS mailing list' <centos at 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.

Hi,

I had trouble with this some years ago and remember someone posting how to
stop it.

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

Thanks

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-*

On 01/13/2017 07:10 AM, Gordon Messmer wrote:
> 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
>
Thank you!

-----Original Message-----
From: CentOS [mailto:centos-bounces at 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.

:-(