DNS configuration in containers ignores my directives.

[IgaRyu]

Hello guys.

I have a problem with containers and the configuration of the DNS server to be used for internet traffic: regardless of how I configure the DNS servers to be used, whether it is:

1. via proxmox webgui
2. via network configuration from proxmox webgui
3. via file /etc/resolv.conf
4. via manual modification of the pve configuration file (/etc/pve/lxc/XXX.conf)

When I restart the container, every somthing modifies the /etc/resolv.conf source, file assigning, as DNS servers to be used, the DNS of my provider and not mine.

I have two of my own DNS servers: a classic one using dnsmasq, and another one with PiHole on two different containers, and they work perfectly, but I can't get them to be used automatically by my containers, because at each restart or network service restart, PVE assign themselves the DNS servers of my provider.

cat /etc/resolv.conf

nameserver 2a05:9d40:dc1:d1::2
nameserver 2a05:9d40:dc2:d2::2

whois 2a05:9d40:dc1:d1::2

inet6num:       2a05:9d40::/32
netname:        IT-SPADHAUSEN-SRL-BACKBONE
country:        IT

Spadhausen is my internet provvider.

How can it be resolved so that the containers use the DNS servers that I want? Of course, excluding manual modification, or via script, at each restart?


Thanks to anyone who can point me a way to solve this annoying problem.

IG

 

[IgaRyu]

After doing some tests, I came to this conclusion:


If I configure the network card to get data from the DHCP6 server, there is no way I can set the DNS servers I want: any attempt always leads to the same result, that is, the DNS loaded in /etc/resolv.conf are always those of the DHCP6 server.


Even if I set IPv4 to static and IPv6 to DHCP6 the result is always the same.


So I set the IPv6 values manually, taking those that the DCP6 offers me: I set the mask address /128 I put the gateway of my provider, and in this way the DNS servers that I want in /etc/resolv.conf remain but... IPv6 no longer works!!!


In the end, the only way in which I can get what I need is:

1. set IPv4 manually
2. set IPv6 via DHCP6
3. create a script that runs at the end of the boot, adding:

echo "nameserver 192.168.1.106" > /etc/resolv.conf
echo "nameserver 192.168.1.101" >> /etc/resolv.conf

What I can't understand is why if I manually set IPv6, with the IPs provided by the DHCP6, the v6 network no longer works...


I don't know what to do anymore: any suggestions?

 

[IgaRyu]

At least I found my way, sure not the best way:

Create a file in /etc/network/if-up.d/ (I named it force-resolv)

File content in my case

#!/bin/bash
echo "nameserver 192.168.1.106" > /etc/resolv.conf
echo "nameserver 192.168.1.101" >> /etc/resolv.conf

set it executable:

chmod u+x /etc/network/if-up.d/force-resolv

… done

When I reboot, the file in /etc/network/if-up.f/ is executed automatically onece the lan configuration is loaded ad set up.

I know this does not solve the problem of IPv6 not working if I set eth0 inet6 dhcp, but at least I've my dns pointend as I wanted.