65

I do not want network manager to add DNS servers received from DHCP to my /etc/resolv.conf.

When configuring from GUI/Connections/IPV4 and choose the method Automatic (address only) it still adds DNS servers received via DHCP.

Is it possible to do it per connection (specific ssid ?)

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2
  • If you choose method "Automatic (DHCP) addresses only" then NetworkManager won't, or shouldn't, change resolv.conf when activating that connection. If NetworkManager does in fact add addresses to resolv.conf despite the "addresses only" setting then there is a bug in NetworkManager and you should report that bug using Launchpad. To stop NetworkManager from changing resolv.conf you should select "Automatic (DHCP) addresses only" in all connection configurations that become active on your system.
    – jdthood
    May 18, 2015 at 10:31
  • 3
    You can either use GUI in the IPv4 settings on the connection and choose "adddresses only" in the mode, or, do what it does yourself by editing the corresponding connection file in /etc/NetworkManager/system-connections/ and adding ignore-auto-dns=true line to the [ipv4] section.
    – Sasha Pachev
    Jul 25, 2019 at 2:12

4 Answers 4

Reset to default
75

One way to stop Network Manager from adding dns-servers to /etc/resolv.conf file is to do this:

First open the nm conf file /etc/NetworkManager/NetworkManager.conf:

sudo vim /etc/NetworkManager/NetworkManager.conf

And add this to the [main] section:

dns=none
rc-manager=unmanaged

Save and exit.

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15
  • /etc/resolv.conf is typically a symlink - are you sure making it immutable makes the target of the link also immutable?
    – muru
    May 15, 2015 at 9:19
  • 8
    This doesn't work for me in debian jessie
    – Dimitri Kopriwa
    Jan 5, 2016 at 16:06
  • 11
    This does not work on Ubuntu 18.04
    – LuizAngioletti
    Sep 3, 2018 at 2:21
  • 9
    I had to sudo service network-manager restart before the change to the .conf file took effect.
    – Chris Moore
    Nov 6, 2018 at 14:30
  • 1
    Worked for me on Ubuntu 18.10, I had to run restart network manager as Chris above stated.
    – Rwky
    Jan 31, 2019 at 22:31
7

/etc/resolv.conf is symlinked to /run/resolvconf/resolv.conf. NetworkManager doesn't update /etc/resolv.conf directly (only updates /run/resolvconf/resolv.conf). So:

  • remove symlink (rm /etc/resolv.conf)
  • write you own version of /etc/resolv.conf
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5
  • 4
    I know this is a ubuntu forum but while googling for centos this was still my first google result, so posting comment for future centos googlers. this did not solve my problem on centos. It appears the centos network manager is directly working on /etc/resolv.conf.
    – Tommy
    Dec 15, 2016 at 18:56
  • 1
    This is not true for Debian Stretch most certainly. It removes your file and replaces it with another symlink. Very annoying.
    – RichieHH
    Mar 8, 2017 at 7:40
  • 1
    Here is one for (virtualized) Fedora 25 using nmcli: In /etc/sysconfig/network-scripts/ifcfg-ens3 we see that PEERDNS=yes which means (in this case, wrong) DNS information is obtained by DHCP, and it ends up in /etc/resolv.conf. I just want 127.0.0.1 as nameserver. Running nmcli con mod ens3 ipf4.ignore-auto.dns yes result in PEERDNS=no in the interface config file. However /etc/resolv.conf still has stray namseserverentry, so if have to restart the connection nmcli con down ens3; nmcli con up ens3. See also: certdepot.net/rhel7-configure-ipv4-addresses
    – David Tonhofer
    Apr 13, 2017 at 16:37
  • 1
    On Ubuntu 18.04, restarting 'service network-manager restart' will cause NM to overwrite /etc/resolv.conf even if it is a hard file and not a symlink.
    – LuizAngioletti
    Sep 3, 2018 at 2:27
  • The symlink and (/run/resolvconf/resolv.conf) does not existing for Arch linux
    – xx1xx
    Aug 11, 2020 at 4:07
5

My personal favorite is to use line supersede domain-name-servers in /etc/dhcp/dhclient.conf. No matter what dns access point provides , your ubuntu will always use those dns specified in dhclient.conf

Sample from my file

#send host-name "andare.fugue.com";
send host-name = gethostname();
#send dhcp-client-identifier 1:0:a0:24:ab:fb:9c;
#send dhcp-lease-time 3600;
#supersede domain-name "fugue.com home.vix.com";
supersede domain-name-servers 208.67.220.220;
#prepend domain-name-servers 127.0.0.1;
request subnet-mask, broadcast-address, time-offset, routers,
    domain-name, domain-name-servers, domain-search, host-name,
    dhcp6.name-servers, dhcp6.domain-search,
    netbios-name-servers, netbios-scope, interface-mtu,
    rfc3442-classless-static-routes, ntp-servers,
    dhcp6.fqdn, dhcp6.sntp-servers;
#require subnet-mask, domain-name-servers;
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2
  • creating a line as described (using server 8.8.8.8) does not work on Ubuntu 18.04.
    – LuizAngioletti
    Sep 3, 2018 at 2:26
  • 3
    @LuizAngioletti 18.04 is using different type of network manager application, called netplan. This answer was written for pre-18.04 releases. I may update it later, though.
    – Sergiy Kolodyazhnyy
    Sep 3, 2018 at 2:41
2

Just in case I have done a little script to do that automatically (here with google DNS) for every ethernet/wireless connections:

nmcli -g name,type connection  show  --active | awk -F: '/ethernet|wireless/ { print $1 }' | while read connection
do
  nmcli con mod "$connection" ipv6.ignore-auto-dns yes
  nmcli con mod "$connection" ipv4.ignore-auto-dns yes
  nmcli con mod "$connection" ipv4.dns "8.8.8.8 8.8.4.4"
  nmcli con down "$connection" && nmcli con up "$connection"
done
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