OpenVZ containers losing their IPv6 connectivity

Brueggus · November 2023

I have OpenVZ services with two providers which I consider proficient. Inception Hosting uses SolusVM while AlphaVPS has a panel integrated into WHMCS but I suspect it's SolusVM in the background as well.

My services with both providers started showing IPv6 issues recently: I can still ping their default gateway from my VM but don't get any further. I don't see any incoming traffic in my VM and when I try to ping it from outside, I get Destination unreachable: Address unreachable from their gateway IP.

Pressing "Reconfigure networking" in SolusVM restores connectivity for a minute or so until it drops again. I have opened tickets with both providers several days ago but they seem to be unable to resolve it.

Has anyone seen (and solved) similar issues before and could provide some information which may help the providers to get this sorted? Could this be just another weird SolusVM issue?

iandk · November 2023

I'm not 100% sure as we don't use OpenVZ but I think @Abdullah commented on a similar issue a while ago

SGraf · November 2023

try running a traceroute "out".

Does it end on the first hop? or does it go a few hops ?

Brueggus · November 2023

@SGraf said: Does it end on the first hop? or does it go a few hops ?

It ends on the first hop:

# mtr -bz --report google.com
Start: Tue Nov 14 14:15:34 2023
HOST:       .      .de          Loss%   Snt   Last   Avg  Best  Wrst StDev
  1. AS62240 2a0f:93c1:26:40::beb  0.0%    10    0.1   0.1   0.1   0.2   0.0
  2. AS???   ???                  100.0    10    0.0   0.0   0.0   0.0   0.0

SGraf · November 2023

@Brueggus said:

@SGraf said: Does it end on the first hop? or does it go a few hops ?

It ends on the first hop:

# mtr -bz --report google.com
Start: Tue Nov 14 14:15:34 2023
HOST:       .      .de          Loss%   Snt   Last   Avg  Best  Wrst StDev
  1. AS62240 2a0f:93c1:26:40::beb  0.0%    10    0.1   0.1   0.1   0.2   0.0
  2. AS???   ???                  100.0    10    0.0   0.0   0.0   0.0   0.0

From the outside towards you. Looks like i get close but not yet. (about no response past the 8th hop).

Host                                                       Loss%   Snt   Last   Avg  Best  Wrst StDev
 1-6....Removed...
 7. AS62240  2a0f:93c1:26::1 
 8. (no route to host)

mikho · November 2023

Ask them if they have ebtables enabled.
I’ve seen this happen, especially if the OVZ containers are run inside a KVM.

FrankZ · November 2023

I run OpenVZ 7 in a few large KVMs and have had no issues with IPv6 Inbound or outbound in the containers. I don't enable ebtables and just run iptables, so what @mikho said about ebtables makes sense as a possible reason.

Brueggus · November 2023

IPv6 is working stable again on both of my AlphaVPS services. I don't know what they did exactly to make it work.

I also got a detailed response to my ticket from Anthony at Inception Hosting. Apparently it's some issue with SolusVM that breaks IPv6 connectivity. They're phasing out OpenVZ services, so we've agreed on letting my service expire. Hopefully I'll be able to pick up a replacement during the BF sale.

OpenVZ containers losing their IPv6 connectivity

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