[SOLVED] Invalid packets from Proxmox causes Proxmox server to be unreachable

A

arnoproxmox

Active Member
Nov 23, 2020
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Hi,

Setup:
Client -> Router -> Proxmox server
All on the same subnet

When the router is configured to drop invalid packets the Proxmox server is unreachable.
When the option is disabled on the router the proxmox server is reachable.

That is, I've been told, because Proxmox tries to route packets on the same subnet. Routing on the same subnet is invalid.
Proxmox uses a bridge (vmbr0) instead of an interface like eth0 so is routing packets on the same subnet.

Can the Proxmox networking configuration be changed in a way that:
- the option "drop invalid packets" on the router can be enabled and
- the Proxmox server is reachable
 
Following on from your post on the Openwrt forum..

Proxmox uses a bridge (vmbr0) instead of an interface like eth0 so is routing packets on the same subnet.

Just because it uses a bridge(vmbr0) shouldn't cause it to route packets on the same subnet, my proxmox server configuration certainly doesnt!
can you post your /etc/network/interfaces configuration
 
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Yes, this does not make any sense to me. Routing involes two subnets, with just one, nothing can be routed.

arnoproxmox said:
When the router is configured to drop invalid packets the Proxmox server is unreachable.
Click to expand...
From where to where ... please explain in detail what you have, what you want and what is not working as expected. Without any information we have to conclude "works for me and another one million installs without any problem".
 
MisterW said:
I may have found the culprit.
Click to expand...
No that was 5 years ago and I checked just now: File is gone. I think due to upgrades/migrations/re-installs.
LnxBil said:
From where to where .
Click to expand...
Any packet that passes through the router. All invalid packets are being dropped.
As I wrote in my first post:
Client, router and server all in the same subnet. Client connected to router, router connected to Proxmox server.
MisterW said:
Just because it uses a bridge(vmbr0) shouldn't cause it to route packets on the same subnet
Click to expand...
Just wrote what the people at OpenWrt wrote. Their explanation is too complicated for me. I took the bottom line: It is a Proxmox configuration problem.

MisterW said:
/etc/network/interfaces configuration
Click to expand...

Code: 
source /etc/network/interfaces.d/*

auto lo
iface lo inet loopback

auto eno1
iface eno1 inet manual

iface eno2 inet manual

auto vmbr0
iface vmbr0 inet static
    address 192.168.3.3
    gateway 192.168.3.1
    bridge-ports eno1
    bridge-stp off
    bridge-fd 0

auto vmbr1
iface vmbr1 inet static
    address 192.168.3.201/32
    bridge-ports none
    bridge-stp off
    bridge-fd 0

auto vmbr2
iface vmbr2 inet static
    address 192.168.3.202/32
    bridge-ports none
    bridge-stp off
    bridge-fd 0
 
@arnoproxmox

you haven't got an explicit netmask on vmbr0. I would have expected a /24 .
what is the purpose of vmbr1 & vmbr2 ? they have no ports and a /32 subnet ?
 
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MisterW said:
what is the purpose of vmbr1 & vmbr2 ? they have no ports and a /32 subnet ?
Click to expand...
They are used for hosting files on a webserver (proxmox-mirror). For extra IP addresses (and extra local dns entries)
MisterW said:
you haven't got an explicit netmask on vmbr0. I would have expected a /24 .
Click to expand...
Installed Proxmox on top of Debian using a Proxmox guide. Did I forget a setting? Should it be /24?
 
Should it be /24?

That's what I would expect. I'm not sure what it would default to when none specified

I certainly have an explicit /24 as in

Code: 
auto vmbr0
iface vmbr0 inet static
        address 192.168.5.63/24
        gateway 192.168.5.1

I just installed Proxmox bare-metal from the distribution which uses Debian as the underlying OS
 
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arnoproxmox said:
Setup:
Client -> Router -> Proxmox server
All on the same subnet
Click to expand...
This vague description seems contrary.
If all is the same subnet, then the traffic doesn't use a router, by definition.

So, exactly, what are the IP addresses of the client, the router, the Proxmox server?
[ addition ]: and what are the netmasks of them?
 
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If all is the same subnet, then the traffic doesn't use a router, by definition.
Click to expand...

and that was the problem , with no subnet specified , it would seem Proxmox/debian didnt think it was in the same subnet and therefore routed it via the specified gateway. In this case the gateway was Openwrt which didnt expect the packet to be routed since it KNEW the destination was in the same subnet
 
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