DNS Problem in bridged networking

[BluesBrother]

Hi,

I´ve a strange problem on availability in DNS with proxmox 8.22

my-Configuration-Schema:
--------------------------------------------
enp0s31f6 -> single network interface with public IP on Hostprovider

//Used Nating to avoid MAC conflicts

vmbr0 10.10.10.1 (private network)
gateway is 10.10.10.1

subhost 1 - 10.10.10.10 (debian)
subhost 2 - 10.10.10.20 (debian)
subhost 3 - 10.10.10.30 (debian)

-------------------------
All Hosts in vmbr0 are available and pingable

my Problem is the DNS is not available via 10.10.10.1 . how i can solve it ?
thanx in Forward !

Toby

-----/interfaces file of proxmox host-system:

source /etc/network/interfaces.d/*

auto lo
iface lo inet loopback

iface lo inet6 loopback

#real IP address
auto enp0s31f6
iface enp0s31f6 inet static
address 95.216.112.185/26
gateway 95.216.112.129

auto vmbr0
#private sub network
iface vmbr0 inet static
address 10.10.10.1/24
bridge-ports none
bridge-stp off
bridge-fd 0

post-up echo 1 > /proc/sys/net/ipv4/ip_forward
post-up iptables -t nat -A POSTROUTING -s '10.10.10.0/24' -o enp0s31f6 -j MASQUERADE
post-down iptables -t nat -D POSTROUTING -s '10.10.10.0/24' -o enp0s31f6 -j MASQUERADE

 

[KevinS]

Have you set up an DNS-Server on the proxmox host? Is it listening to the right interface/ip address?

try to do a tcpdump on the host machine like this to see if the requests are reaching the host, if not (and the pings are working as described) it means the DNS Server is not up and running or not listening to UDP53, you can check with

ss -tulpn | grep '53'