Single IP on Kimsufi VPS

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lwx4w

New Member
Nov 5, 2025
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Hello

I have a Kimsufi VPS with a single public IP address.

I installed Proxmox 9 and I can access the graphical administration console.

I want to create internal networks, vmbr1, vmbr2, and vmbr3 => I created:

vmbr1 will contain one Ubuntu server responsible for assigning IP addresses via DHCP to the VMs in vmbr2 and vmbr3.

vmbr2 will be able to access the internet through vmbr1 but will not be able to communicate with vmbr3.

vmbr3 will not have internet access and will not be able to communicate with vmbr2.

I'm encountering a problem as soon as I create the first VM in vmbr1.

My VM doesn't have internet access.

I haven't done any configuration.

Can you help me with the configuration?

Thank you
 
Hi,

It looks like the issue is missing NAT/Routing configuration on the Proxmox host.
If I'm didn't miss something in your description, you need to enable IP forwarding and set up iptables NAT (MASQUERADE) rules on the Proxmox host to route traffic from the internal bridges (vmbr1, vmbr2, etc.) out through the public interface (vmbr0).
https://pve.proxmox.com/wiki/Network_Configuration
 
Hello
Thank you for the reply
Here's how I configured vmbr1

nano /etc/network/interfaces

auto vmbr1
iface vmbr1 inet static
address 192.168.1.1/24
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 192.168.1.0/24 -o vmbr0 -j MASQUERADE
post-up /root/dnat.sh
post-down iptables -t nat -D POSTROUTING -s 192.168.1.0/24 -o vmbr0 -j MASQUERADE
 
G

[SOLVED] Post in thread 'Proxmox 8.3.3 - guest windows server 2019 no internet'

Remember as per Docs :
In some masquerade setups with firewall enabled, conntrack zones might be needed for outgoing connections. Otherwise the firewall could block outgoing connections since they will prefer the POSTROUTING of the VM bridge (and not MASQUERADE).
Adding these lines in the /etc/network/interfaces can fix this problem:

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
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