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bug: resolv.conf auto-populates search and nameserver seeking: permanent or temporary (run each time system boots.)

recommended solution: resolvconf package solves the auto-population issue (not to be confused with resolv.conf)

-https://www.youtube.com/watch?v=NEyXDdBrw2c
-https://unix.stackexchange.com/q/209760/441088
-https://unix.stackexchange.com/q/362587/441088

My question is identical to the last (441088) except need resolv.conf to no longer update (auto-populate) search and nameservers

#sudo vi resolv.conf

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by    resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual   nameservers.
nameserver 84.200.70.40
nameserver 84.200.69.80
nameserver 192.168.4.1 
nameserver 192.168.4.1
nameserver 192.168.1.1
nameserver 1.1.1.1
search autopopulated-isp-router 1.1.1.1

apparently it just adds additional auto-populated nameservers below the already existing. (it is a little sneaky so you must keep checking resolv.conf to catch the auto-population of nameservers & search server, which are auto-appended to resolvconf settings)

how can i change the resolv.conf to prevent auto-populating of nameserver and search with isp ip addresses?

Tried with:

# service networking stop && service network-manager start
# service networking start && service network-manager stop

Network managers:
Wicd with both networking and network-manager stopped,
then no wicd just nmtui with networking start then with network-manager start

Replicable on debian 10.1 and kali 2020 (any version - tried them all)

Replicable with dhcp or static configuation (yes able to ping local gateway network router and other ip's on network)

# /etc/nsswitch.conf
#
# Example configuration of GNU Name Service Switch functionality.
# If you have the `glibc-doc-reference' and `info' packages installed,     try:
# `info libc "Name Service Switch"' for information about this file.

passwd:         files systemd
group:          files systemd
shadow:         files
gshadow:        files


hosts:          files mdns4_minimal [NOTFOUND=return] dns myhostname     mymachines
networks:       files


protocols:      db files
services:       db files
ethers:         db files
rpc:            db files


netgroup:       nis
terdon
  • 242,166
rakis
  • 9
  • "My question is identical to the last (441088) except need resolv.conf to no longer update (auto-populate) search and nameservers" ... What? What last question? What are you referring to? – 0xSheepdog Oct 31 '23 at 01:29

2 Answers2

0

I think the issue here is with NetworkManager that is populating your resolv.conf file.

To disable dns updates.

1- Open the conf file with an editor :

sudo vi /etc/NetworkManager/NetworkManager.conf

2- Add the above to [main] section : dns=none

3- Restart NetworkManager :

sudo service network-manager restart

SINCE you last EDIT :

As I see here you are using NetworkManager.service :

A- If you are using dhcp for your interface, then check the DNS setup by your DHCP server :

cat /var/lib/NetworkManager/*.lease | grep 'domain-name-servers'

You can set directly your dns entries needed in this case and disabling DHCP from supplying them :

# Edit dhclient configuration file
vi /etc/dhcp/dhclient.conf
# Set the fixed your dns server entries
supersede domain-name-servers 84.200.69.80, 84.200.70.40;

B- It's clear here that your /etc/resolv.conf is clearly managed by systemd-resolved service.

So you can disable this service or let it running and edit its configuration in /etc/systemd/resolved.conf, so to disable it :

1- First check the output of the current systemd-resolved.conf file & check systemd-resolved is running :

sudo cat /run/systemd/resolve/resolv.conf
sudo systemd-resolve status

2- Stop / Disable the service :

  sudo systemctl disable systemd-resolved.service
  sudo systemctl stop systemd-resolved.service

3- Set the DNS processing mode in NetworkManager so it will not be anymore managed by systemd-resolved nor NetworKService ( Edit /etc/NetworkManager/NetworkManager.conf ) :

  [main]
  dns=none

4- Destroy the symlink /etc/resolv.conf -> /run/systemd/resolve/resolv.conf :

sudo unlink /etc/resolv.conf

5- Restart NetworkManager :

sudo systemctl restart NetworkManager

6- Recreate resolv.conf file :

sudo touch /etc/resolv.conf
sudo chown root:root /etc/resolv.conf
sudo chmod 644 /etc/resolv.conf

7- Populate manually resolv.conf file :

echo 'nameserver 84.200.70.40
nameserver 84.200.69.80
nameserver 192.168.4.1 
nameserver 192.168.4.1
nameserver 192.168.1.1
nameserver 1.1.1.1' > /etc/resolv.conf
Reda Salih
  • 1,754
  • yeah, i service network-manger stop && service networking stop....using wicd to avoid network manger from doing its thing... but still dns autopopulates even with resolveconf package installed. I will try editing the networkmanger.conf...maybe ip is picking it up somewhere. IP tends to mysteriously popup sometimes even with ip down – rakis Nov 08 '20 at 23:15
  • ok then use only network service and disable network-manager you have to use only one of these two services. Could you mark my response as answered. – Reda Salih Nov 08 '20 at 23:17
  • after a day of testing. neither network service (networking) nor network-manager being used prevents search from auto-populating. – rakis Nov 10 '20 at 17:32
  • so what is the networking service you are using ? what is your distribution & VERSION ? also if you can publish resolv.conf file and /etc/nsswitch.conf ? are you using dhcp ? you can edit your question to be more clearer. – Reda Salih Nov 10 '20 at 17:35
  • will try fixes https://unix.stackexchange.com/q/273565/441088 and add findings to post. – rakis Nov 10 '20 at 20:37
0

I've made a script to change resolv.conf file permanently:

#!/usr/bin/env bash
f="/etc/resolv.conf"
chattr -i "$f"
rm -f "$f"
echo "nameserver 1.1.1.1" >> "$f"
echo "nameserver 8.8.8.8" >> "$f"
chattr +i "$f"

This script makes the file immutable, so it will not be changed and cannot be deleted. To delete the file you need to use command:

chattr -i /etc/resolv.conf

Then delete the file.

pbies
  • 464
  • Nothing like a sledgehammer to drive a finishing nail... I mean, you're not wrong; this will work. – 0xSheepdog Oct 31 '23 at 01:27
  • But this would break anything that needs to write to resolv.conf, so any kind of GUI tool or wrapper etc. It is only useful if you only want to edit the file manually. – terdon Oct 31 '23 at 14:50