David Christensen wrote on Wed, 31 Mar 2021 13:49:56 -0700:
I would do 'apt-get update' and 'apt-get upgrade' ('autoremove',
'clean', etc.). Once apt-get(8) is done, I would revert the changes
to /etc/resolv.conf and see if name resolution breaks or remains
working. (I would test by renaming /etc/resolve.conf and rebooting.)
Here is what I did:
# apt update
# apt upgrade
# apt autoremove
# apt-get clean
# cp /etc/resolv.conf /etc/resolv.confX
# chattr -i /etc/resolv.conf
## to make resolv.conf *not* immutable
# cat /etc/resolv.conf
domain attlocal.net
search attlocal.net
nameserver 1.1.1.1
nameserver 1.0.0.1
nameserver 192.168.1.254
Shutdown then power-on boot
## rebooted with /etc/resolv.conf *not* immutable
root@deb4:~# ping google.com
ping: google.com: Temporary failure in name resolution
root@deb4:~# cat /etc/resolv.conf
domain attlocal.net
search attlocal.net
nameserver 192.168.1.254
## showing that /etc/resolv.conf has been clobbered
After restoring resolv.conf so that it looks like this:
# cat /etc/resolv.conf
domain attlocal.net
search attlocal.net
nameserver 1.1.1.1
nameserver 1.0.0.1
nameserver 192.168.1.254
# chattr +i /etc/resolv.conf
## making it immutable
Rebooted and posted this.