Home / ubuntu / Questions / 1117878
In Process
Tom
Asked: 2019-02-14 02:06:23 +0800 CST

Network manager DNS settings

  • 772

I have my laptop connected to a wifi network that is 192.168.1.0/24. I then have that wifi adapter bridged to br0. I then connect a tap-to-tap tunnel tap1 onto a network that is 10.40.0.0/14.

My wifi network has a DNS server at 192.168.1.254 while the remote network has a DNS server at 10.40.0.2. When the tap-to-tap tunnel comes up, I delete its default route so that only traffic to that network will go over the tunnel and general Internet traffic goes over the usual wifi link. But I want to use the remote network's DNS server so that I can still look up local names on the remote network.

nmcli device show wlan0 says this (I've removed various irrelevant bits for brevity, mostly ip6 and routing information):

GENERAL.DEVICE:                         wlan0
GENERAL.TYPE:                           wifi
GENERAL.STATE:                          100 (connected)
GENERAL.CONNECTION:                     channel-six
IP4.ADDRESS[1]:                         192.168.1.82/24
IP4.GATEWAY:                            192.168.1.254
IP4.DNS[1]:                             192.168.1.254
IP4.DNS[2]:                             10.40.0.2
IP4.DOMAIN[1]:                          lan

This says that this device has both DNS servers assigned to it. But nmcli con show channel-six says this:

connection.id:                          channel-six
connection.uuid:                        34402de9-ec2d-4a4e-a223-9bea7fc5b517
...
ipv4.dns:                               10.40.0.2
ipv4.dns-search:                        --
ipv4.dns-options:                       ""
ipv4.dns-priority:                      0

So why is NetworkManager using the local DNS server? How can I change it?

networking vpn network-manager dns

1 Answers

  1. The local DNS is being picked up from DHCP. This can be fixed like this:

    $ nmcli con modify channel-six +ipv4.ignore-auto-dns yes
$ nmcli con up channel-six

    The modify command can also have --temporary added to make this a temporary change. The con up is necessary to apply the change.

    • 1