Proxmox 8 - NAT Configuration

[Florian-s]

Hello everyone,

I have a problem with my nat configuration. At the moment my server is constantly blocked by my hoster because they receive a message from an external organisation that my server is using an IP address that is not assigned to it. This address is my internal IP 10.10.10.1.

I have configured the firewall and actually set the NAT settings so that the internal IPs actually run via my main IP.

According to tcpdump, the ping from a VM also works correctly and uses the main IP.

However, there must still be an error somewhere, otherwise my hoster would not keep blocking the server because of it.

Here my /etc/network/interfaces configuration:

auto lo
iface lo inet loopback

auto eno1
iface eno1 inet manual

iface eno2 inet manual

auto vmbr0
iface vmbr0 inet static
address 194.xxx.xx.31
gateway 194.xxx.xxx.1
netmask 255.255.255.0
bridge-ports eno1
bridge-stp off
bridge-fd 0

auto vmbr1
#private sub network
iface vmbr1 inet static
address 10.10.10.1
netmask 255.255.255.0
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 vmbr0 -j MASQUERADE
post-down iptables -t nat -D POSTROUTING -s '10.10.10.0/24' -o vmbr0 -j MASQUERADE
post-up iptables -t raw -I PREROUTING -i fwbr+ -j CT --zone 1
post-down iptables -t raw -D PREROUTING -i fwbr+ -j CT --zone 1

I would be very happy if someone could help me!

Best regards