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Accepted
hiro protagonist
Asked: 2015-10-06 22:51:40 +0800 CST

change DNS server in a non-persistent way (on the command-line) [rescue mode]

  • 772

is there a way i can change the DNS server on the command-line without having to change anything on the disk?

i recently booted into the rescue session and i got an IP address (using DHCP) but no DNS server. as my network config is usually done with the nm-applet in the desktop session and not in /etc/network/interfaces i would like to be able to provide a DNS server just for this rescue session and not write anything on disk.

this is usually possible by editing /run/resolvconf/resolv.conf. but resolvconf seems not to be running in the ubuntu 14.04 rescue session.

i was hoping there was something similar to the network configuration where i can configure an interface without having to edit a file:

# ifconfig eth0 192.168.2.5 netmask 255.255.255.0
# route add default gw 192.168.2.1

is there a way to do this for DNS in a rescue session on ubuntu 14.04?

16.04

3 Answers

  1. Best Answer

    i found a way to do this:

    kill the dns service (there may be a more subtle way?)

    # killall dnsmasq

    restart the service using the desired upstream server:

    # dnsmasq --server=192.168.2.1

    on a newer ubuntu (one with systemd) this would be:

    # systemd-resolve -i enp0s31f6 --set-dns=192.168.2.1  # --set-dnssec=true

    check with:

    # systemd-resolve --status
    • 6

  2. Navigate to this directory /etc/resolvconf/resolv.conf.d edit the head file using vi or vim with su privilege

    sudo vi /etc/resolvconf/resolv.conf.d/head

    add the following lines to the file

    nameserver *DNS server IP*

    save the file and use resolvconf utility to set the static DNS server address you entered by the following command

    sudo resolvconf -u
    • 0

  3. To get this to work, I added au.archive.ubuntu.com to the /etc/hosts file with an IP address I got from pinging it on my PC.

    Then did apt update and it resolved.

    • 0