Re: [pve-devel] [PATCH pve-cluster] sysctl: disable net.ipv4.igmp_link_local_mcast_reports

[Thomas Lamprecht <t.lamprecht@proxmox.com>]

On 06.10.21 10:32, Alexandre Derumier wrote:
> currently, when veth or tap interfaces are plugged to bridge,
> an igmp v3 report is broadcasted to the network, with the
> bridge mac adddress.

but this disables it for all, couldn't there be repercussions for people relying
on multicast?

Should it be an FW option?

> 
> Users have reported problems with hetzner for example, blocking the server
> because of the unknown mac flooding the network.
> https://forum.proxmox.com/threads/proxmox-claiming-mac-address.52601/page-6#post-421676
> 
> some traces:
> 
> ip addr:
> 
> 190: fwbr109i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
>     link/ether 22:5f:0b:cb:ac:42 brd ff:ff:ff:ff:ff:ff
> 
> ebtable log:
> Oct  6 09:46:24 kvmformation3 kernel: [437256.753355] MAC-FLOOD-F IN=fwpr109p0 OUT=eno1 MAC source = 22:5f:0b:cb:ac:42 MAC dest = 01:00:5e:00:00:16 proto = 0x0800 IP SRC=0.0.0.0 IP DST=224.0.0.22, IP tos=0xC0, IP proto=2
> 
> tcpdump -e -i eno1 igmp
> 09:53:23.914825 22:5f:0b:cb:ac:42 (oui Unknown) > 01:00:5e:00:00:16 (oui Unknown), ethertype IPv4 (0x0800), length 54: 0.0.0.0 > igmp.mcast.net: igmp v3 report, 1 group record(s)
> 
> Signed-off-by: Alexandre Derumier <aderumier@odiso.com>
> ---
>  debian/sysctl.d/pve.conf | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/debian/sysctl.d/pve.conf b/debian/sysctl.d/pve.conf
> index 929698f..85b59b9 100644
> --- a/debian/sysctl.d/pve.conf
> +++ b/debian/sysctl.d/pve.conf
> @@ -2,4 +2,5 @@ net.bridge.bridge-nf-call-ip6tables = 0
>  net.bridge.bridge-nf-call-iptables = 0
>  net.bridge.bridge-nf-call-arptables = 0
>  net.bridge.bridge-nf-filter-vlan-tagged = 0
> +net.ipv4.igmp_link_local_mcast_reports = 0
>  fs.aio-max-nr = 1048576
>