Bridged Network - Gateway not reachable

[thomas-hn]

Hi,

my Proxmox VE is running as a nested VM on top of Hyper-V and inside PVE a Debian VM is running.
Graphically it looks like this:

Router (192.168.10.1) ---- Hyper-V Switch (Windows 192.168.10.101) ---- Hyper-V VM with Proxmox VE (192.168.10.111) --- PVE VM with Debian (192.168.10.71)

The current status is:

• Proxmox can ping all other IP addresses.
• Router can ping Proxmox VE
• Windows can ping Proxmox VE
• Router cannot ping Debian
• Windows cannot ping Debian
• Debian can ping Proxmox VE
• Debian cannot ping Windows
• Debian cannot ping Router

The current network configuration of Proxmox VE is:

root@pve:~# cat /etc/network/interfaces
auto lo
iface lo inet loopback

iface eth0 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.10.111/24
        gateway 192.168.10.1
        bridge-ports eth0
        bridge-stp off
        bridge-fd 0

The current network configuration of Debian is:

user@Debian:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback

auto enp6s18
iface enp6s18 inet static
    address 192.168.10.71
    netmask 255.255.255.0
    network 192.168.10.0
    broadcast 192.168.10.255
    gateway 192.168.10.1
    dns-nameservers 192.168.10.1

Do you have any ideas what is wrong?

Thanks a lot in advance,

Thomas

 

[rason]

It looks like the issue might be with the networking configurations on the Proxmox VE and Debian VM. In the Proxmox VE configuration, the eth0 interface is set to "manual" instead of being assigned an IP address, which could be causing issues with connectivity. Additionally, in the Debian configuration, the network interface (enp6s18) is not specified as being a part of the bridge (vmbr0) on the Proxmox VE.
Try modifying the configurations to include the proper IP addresses and bridge connections, and see if that resolves the connectivity issues.
For the Proxmox VE configuration, it should look something like this:

auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 192.168.10.111/24
gateway 192.168.10.1
auto vmbr0
iface vmbr0 inet static
bridge-ports eth0
bridge-stp off
bridge-fd 0

And for the Debian configuration, it should look something like this:

auto lo
iface lo inet loopback
auto enp6s18
iface enp6s18 inet static
address 192.168.10.71
netmask 255.255.255.0
network 192.168.10.0
broadcast 192.168.10.255
gateway 192.168.10.1
dns-nameservers 192.168.10.1
bridge_ports vmbr0

After making these changes, restart the network services on both the Proxmox VE and Debian VM and see if the connectivity issues are resolved.
Let me know if this helps or if you have any further questions.

 

[thomas-hn]

It looks like the issue might be with the networking configurations on the Proxmox VE and Debian VM. In the Proxmox VE configuration, the eth0 interface is set to "manual" instead of being assigned an IP address, which could be causing issues with connectivity. Additionally, in the Debian configuration, the network interface (enp6s18) is not specified as being a part of the bridge (vmbr0) on the Proxmox VE.
Try modifying the configurations to include the proper IP addresses and bridge connections, and see if that resolves the connectivity issues.

Hi rason,

thanks for your help. To be honest, I have not tried your proposal, yet, because I would like to understand it first.
The configuration of the Proxmox VE host was never modified manually and was completely automatically generated during the Proxmox installation. Therefore, I am struggling to believe that it shall be wrong to have the IP address of the Proxmox host be assigned to vmbr0 instead of eth0. If I try to change the Proxmox IP address from vmbr0 to eth0 via the Web GUI, Proxmox reports an error, telling that I cannot assign an IP address to eth0 as long as this interface is part of the bridge.

The second point I don't fully understand is why I have to tell the Debian VM in its network configuration that it shall participate on vmbr0. For my understanding the Debian VM is virtualized and should not know about the bridge vmbr0 which is outside the VM. I think the VM should only see a "normal" network interface.

Could you give me some more details, please?

Thanks,

Thomas

 

[leesteken]

Your Proxmox bridged network configuration looks normal to me.
I would expect a slightly simpler Debian network configuration (but I doubt that it matters), here is mine for a Debian VM (adjusted for your IPs):
auto ens18 iface ens18 inet static address 192.168.10.71/24 gateway 192.168.10.1 dns-nameserver 192.168.10.1 dns-search lan
I'm surprised your virtual network device name is ens6s18 instead of ens18 but maybe that's because of the nested VMs?
Does your V-switch at 192.168.10.101 route all of 192.168.10.0/24 or just the Proxmox host 192.168.10.111? Probably the latter givens the IP addresses and test results. Maybe your V-switch 192.168.10.101 is using NAT or requires Proxmox to use NAT and port forwarding (because it only routes a single IP address 192.168.10.111)?

 

[Neobin]

Not sure on this, but maybe you need to enable the promiscuous mode on the Hyper-V-NIC (if even possible), like it is the case on VirtualBox: [1]?

[1] https://pve.proxmox.com/wiki/Proxmo...n_requires_VirtualBox_NIC_in_promiscuous_mode

 

[thomas-hn]

I'm surprised your virtual network device name is ens6s18 instead of ens18 but maybe that's because of the nested VMs?
Does your V-switch at 192.168.10.101 route all of 192.168.10.0/24 or just the Proxmox host 192.168.10.111? Probably the latter givens the IP addresses and test results. Maybe your V-switch 192.168.10.101 is using NAT or requires Proxmox to use NAT and port forwarding (because it only routes a single IP address 192.168.10.111)?

Hi,

yesterday I already looked into my Hyper-V-Switch settings, but your comment triggered me again.
I found in the settings of the VM under "Network Interface" the point about activating "MAC Spoofing". This is exactly the option that was not enabled and, therefore, Hyper-V blocked any traffic coming from another MAC address (the MAC address of my Debian VM in Proxmox VE).

Thanks a lot for the hint and sorry for the not Proxmox related issue.