When you flip VLAN-aware on the bridge in node->system->network ?

[shodan]

Hi,

I run dhcp client on proxmox web interface
and I found one of the few problem this causes is that
if you flip the vlan aware flag in node->system->network
then it will revert networking to manual (with no settings)
which renders the server unreachable

So I'm trying to find, exactly what happens and what executes when you change those settings ?



And a related issue, is that, even after resolving the issue (restoring dhcp to the bridge) then none of the VMs had networking until I rebooted them.

So I figure while making this dialog less disruptive, it seems there's also a bug in the networking system that causes bridge reconfiguration to break networking on the VMs and that is probably something that can be fixed as well.

 

[cheiss]

Hi,

I run dhcp client on proxmox web interface

Using DHCP on the host is not supported. That's also why changing any settings in the web UI will automatically set it to static again.
If you really want to use DHCP, it can work, but means editing files by hand and it may break spontaneously since the Proxmox VE stack does not consider this.

So I figure while making this dialog less disruptive, it seems there's also a bug in the networking system that causes bridge reconfiguration to break networking on the VMs and that is probably something that can be fixed as well.

What do you mean exactly here? For this, a lot more information would be needed (/etc/network/interfaces, VM configurations, etc.) - but might also be caused by the DHCP setup.

 

[shodan]

Yes, I know it is not supported, I am trying to resolve the issues related to it.

I've been living with dhcp on the webui for a while, I didn't find any real issues until now, when I tried to flip vlan awareness on the bridge.
And the problem was simply that the script that changes those variables, switched the bridge the manual with empty static values, so the server became unreachable.

This is an easy fix, the script that control this should not rewrite the bridge protocol when asked to switch vlan awareness, it should only touch the vlan awareness lines

auto vmbr0
iface vmbr0 inet dhcp
        bridge-ports enp10s0
        bridge-stp off
        bridge-fd 0
        bridge-vlan-aware yes
        bridge-vids 2-4094

That is an easy fix, I am just asking what is the script that runs after the dialog "Edit: Linux bridge"


But also, I uncovered another issue.

When I ran

systemctl restart networking

Networking on all VMs and all CT containers broke.
And the only way I found to resolve that, was to restart each of them

There is probably a way to repair them without a reboot.
But also the change in bridge configuration should not leave the VMs and CTs in a broken networking state

Also my testing here is on Proxmox 8, this might have been resolved but I doubt it.

Anyway, regardless of whether this is supported or not, I think both of these things should be looked into as I do think they are minor and easy fixes to make these settings less dangerous.

 

[Neobin]

When I ran

systemctl restart networking

Networking on all VMs and all CT containers broke.

Post in thread 'using "systemctl restart networking", Bridge interface disappeared'

Apr 3, 2024

The association of bridge-ports to brigdes used to get lost upon `systemctl restart networking`, which is why Proxmox VE recommends ifupdown2, where you can use `ifreload` (this is also what is exposed on the GUI for reconfiguring the network.

I hope this helps!

• Stoiko Ivanov

• 

[0] https://pve.proxmox.com/pve-docs/chapter-sysadmin.html#_live_reload_network_with_ifupdown2