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HBH ICMP6, multicast listener report - flood
Hi,
Not sure if I monitor my VPSes too closely, but have another networking issue.
On one of my GreenCloud ones I have been noticing packet floods from time to time (this has been intermittently happening since few months now).
Recently the pattern was: every 20 minutes (:00, :20, :40) there was a flood for 1-2 minutes and stopped. Since 12 hours there's constant 3 Mbit/s traffic, around 300-400 packets/s
I've narrowed it to:
16:17:46.342153 IP6 fe80::216:3cff:fead:459c > ff02::16: HBH ICMP6, multicast listener report v2, 72 group record(s), length 1448
16:17:46.346354 IP6 fe80::216:3cff:fead:459c > ff02::16: HBH ICMP6, multicast listener report v2, 72 group record(s), length 1448
16:17:46.350570 IP6 fe80::216:3cff:fead:459c > ff02::16: HBH ICMP6, multicast listener report v2, 72 group record(s), length 1448
16:17:46.354130 IP6 fe80::216:3cff:fead:459c > ff02::16: HBH ICMP6, multicast listener report v2, 72 group record(s), length 1448
16:17:46.357740 IP6 fe80::216:3cff:fead:459c > ff02::16: HBH ICMP6, multicast listener report v2, 72 group record(s), length 1448
16:17:46.361382 IP6 fe80::216:3cff:fead:459c > ff02::16: HBH ICMP6, multicast listener report v2, 72 group record(s), length 1448
16:17:46.364747 IP6 fe80::216:3cff:fead:459c > ff02::16: HBH ICMP6, multicast listener report v2, 72 group record(s), length 1448
16:17:46.368593 IP6 fe80::216:3cff:fead:459c > ff02::16: HBH ICMP6, multicast listener report v2, 72 group record(s), length 1448
the source link-local address tends to change every few weeks. Mac vendor is "Rebox".
Contacted support twice. For the first time they did nothing, rather told me to check in few hours. For the second time suggested few iptables rules that didn't work. In the end they told me to change IPv6 subnet 
After that I gave up asking for their help.
Did quite some investigation on how to block that traffic, nothing worked.
I also found that there was some firmware issue with some networking cards in HP and Lenovo desktops that caused such issues.
Any ideas how to get rid of that traffic on my own, don't think the support has any idea.
This VPS is very low on any other network traffic, majority is caused by this multicast listener report.
CC: @NDTN
Thanks!
Comments
@yoyek Please drop me a PM with your ticket ID so I can take a look at that.
Just a quick update to finish this thread:
@NDTN got GreenCloud support to further debug the issue and it has been sorted, thanks!
Unfortunately I do not know what was the cause, or the fix, so can't leave anything as a possible learning/troubleshooting source.