DNS not working after update

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networkinss
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DNS not working after update

Post by networkinss » Thu Feb 08, 2018 12:46 am

Hello,
after an update of my 18.3 installation, I have serious problems with DNS.
In most nets DNS is simply not working anymore. IP addresses are no problem.
I was using several nets, some ethernet, some wireless.
In some nets I get the correct DNS, and all is working.
But in most nets DNS is not working at all.

I got that problem obviously with the last update (few days ago, maybe a week).

My workaround is currently to work from USB stick, which has a linuxmint 18.2 installation (without updates).
I get there some necessary IPs and put them into the /etc/hosts.

I have the problem on two computer with linuxmint, one was having 18.2.

It might be a problem of the installed VPN.
Found
viewtopic.php?f=157&t=263542
with about the same problems, but it has no solution.

trapperjohn
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Re: DNS not working after update

Post by trapperjohn » Thu Feb 08, 2018 5:05 pm

Hi,

One of my first steps with a Mint install is to set the DNS servers manually and permanently. (Others may disagree with this, but it has worked perfectly for me... for years now.)
If you want to give it a try:

First, decide on your preferred nameserver. I typically use the router (192.168.1.1 in my case) and add the Google DNS as an alternate.

For safety, make a safe copy of /etc/resolv.conf.

Code: Select all

sudo mv /etc/resolv.conf /etc/resolv.safe
Then:

Code: Select all

sudo nano /etc/resolv.conf
make it read:

nameserver 8.8.8.8

#Add other nameserver lines as needed/wanted.

Save it with [cntl]o then close it with [cntl]x

Finally, make it immutable:

Code: Select all

sudo chattr +i /etc/resolv.conf


Test name resolution.



If it doesn't work, then reverse all of that:

Code: Select all

sudo chattr -i /etc/resolv.conf
sudo rm /etc/resolv.conf
sudo mv /etc/resolv.safe /etc/resolv.conf

networkinss
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Joined: Thu Feb 08, 2018 12:33 am

Re: DNS not working after update

Post by networkinss » Fri Feb 09, 2018 6:04 am

My current entry is:
nameserver 209.222.18.222
nameserver 209.222.18.218

I cannot try your solution right now but what happens in DHCP network (like public WiFi) will it change the DNS server or will it take it from resolv.conf file ?

Update:
I checked the nameserver and they are indeed from the VPN I am using sometimes.
So it is a problem of the VPN configuration.
Have to check with them.

Thanks for the help.

I consider this post as being solved.

Pippin
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Re: DNS not working after update

Post by Pippin » Fri Feb 09, 2018 7:35 am

If you want to override DNS servers pushed by ANY gateway/router reliably, you can add

Code: Select all

# Override DNS from any DHCP server
supersede domain-name-servers nameserver 209.222.18.222, 209.222.18.218;
to

Code: Select all

/etc/dhcp/dhclient.conf
This also works together with OpenVPN update-resolv-conf.

Edit:
Typo
"One good thing about music, when it hits you feel no pain.”
B.M.

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