DNS Problem on VM(OMV) in Proxmox

[Krulle]

Hello all,

I have installed promox on a server and have installed a VM with OMV in it. I have the problem that the DNS in OMV does not work.
Proxmox has a static IP at 192.168.0.60.

ping google.de

is working on proxmox, but not on the VM

Output on Promox:

cat /etc/network/interfaces

auto lo
iface lo inet loopback

iface eno1 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.0.60/24
        gateway 192.168.0.1
        bridge-ports eno1
        bridge-stp off
        bridge-fd 0

ip Addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vmbr0 state UP group default qlen 1000
    link/ether 9c:6b:00:00:79:99 brd ff:ff:ff:ff:ff:ff
    altname enp0s31f6
3: vmbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 9c:6b:00:00:79:99 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.60/24 scope global vmbr0
       valid_lft forever preferred_lft forever
    inet6 fe80::9e6b:ff:fe00:7999/64 scope link
       valid_lft forever preferred_lft forever
4: tap100i0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vmbr0 state UNKNOWN group default qlen 1000
    link/ether c6:59:1a:82:a8:0e brd ff:ff:ff:ff:ff:ff

cat /etc/resolv.conf

search local
nameserver 192.168.0.1

ip route

default via 192.168.0.1 dev vmbr0 proto kernel onlink
192.168.0.0/24 dev vmbr0 proto kernel scope link src 192.168.0.60

traceroute 8.8.8.8

 1  fritz.box (192.168.0.1)  0.556 ms  0.692 ms  0.832 ms
 2  * * *
 3  ip-081-210-144-010.um21.pools.vodafone-ip.de (81.210.144.10)  22.239 ms  22.234 ms  18.777 ms
 4  de-str01c-rc1-ae-49-0.aorta.net (84.116.191.133)  24.303 ms  24.298 ms  24.292 ms
 5  de-fra01b-rc2-ae-4-0.aorta.net (84.116.140.201)  27.532 ms  27.527 ms  25.123 ms
 6  de-bfe18a-rt01-lag-1.aorta.net (84.116.190.34)  24.269 ms  19.287 ms  25.280 ms
 7  74.125.48.122 (74.125.48.122)  30.598 ms  27.805 ms  35.066 ms
 8  * * *
 9  dns.google (8.8.8.8)  32.884 ms  29.380 ms  32.873 ms

VM with OMV:
ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 0a:d7:40:27:b2:45 brd ff:ff:ff:ff:ff:ff
    altname enp0s18
    inet 192.168.0.100/24 brd 192.168.0.255 scope global ens18
       valid_lft forever preferred_lft forever

what does brd (Broadcast?) 192.168.0.255 mean and what is it good for?

cat /etc/resolv.conf

#No DNS servers knwon.
search .

ip route

default via 192.168.0.1 dev ens18 proto static
192.168.0.0/24 dev ens18 proto kernel scope link src 192.168.0.100

Does anyone know a solution and can help me?

Thanks.

 

[B.Otto]

Hello,

I don't think that the problem here is on the proxmox side, since there are no network shenanigans (masquerade, separate bridges,..) configured there.

I think your VM either has no DNS server configured or your VM gets blocked by your firewall. To troubleshoot further you can try tracing the steps needed for your connection. Can you ping

• VM -> Proxmox (192.168.0.60) ?
• VM -> Gateway (192.168.0.1) ?
• VM -> static IP in the internet (e.g. 8.8.8.8) ?

Depending on 'how far you get' we can then decide what to do next.

what does brd (Broadcast?) 192.168.0.255 mean and what is it good for?

Every subnet has one IP dedicated for broadcast, basically packets sent to this address are sent to all devices in this subnet. This is usually the last IP address in the subnet. So this display is normal.

Kind regards,
Benedikt

 

[Krulle]

Hey Benedikt,
thanks a lot for your answer. Yes, I agree with you. The problem is on the OMV side.
Yesterday, I still managed to get the DNS to work properly. After updating OMV to a newer version, however, it no longer works.
As soon as I have a solution, I will cross-reference it here. Because I think the problem will occur more often.

 

[Krulle]

Hello,

I'm still stuck and can't get any further.
I found out (by trial and error) that omv is based on netplans. Ok, that is understood.
I installed another stock Debian 11, this time I have the same problem with DNS: I can't get it to work.
In Proxmox I have set the default configuration as described in the instructions https://pve.proxmox.com/wiki/Network_Configuration
I understand that as far as it goes.
But I don't understand why the DNS is blocked by all VMs and CTs. Even if I store different nameservers, I can't get the DNS to work.
I have also activated the IP6 functionality in the router (FritzBox) to see if anything changes.
Do I have to configure anything else in Proxmox or in the router or am I doing something fundamentally wrong?

EDIT:
I have now got the DNS running in the CT: I have assigned a static Ip to the network.