Re: IPFW/IPv6 problem with JAIL: JAIL cannot ping -6 host until host first pings jail (ipv6)

From: Felix Reichenberger <felix.reichenberger_at_tuta.io>
Date: Mon, 08 Jan 2024 00:33:53 UTC

> Hello,
>
> I've got a problem with recent CURRENT, running vnet JAILs.
> FreeBSD 15.0-CURRENT #28 main-n267432-e5b33e6eef7: Sun Jan  7 13:18:15 CET 2024 amd64
>
> Main Host has IPFW configured and is open for services like OpenLDAP on UDP/TCP and ICMP
> (ipfw is configured via rc.conf in this case, host is listening on both protocol families
> IPv4 and IPv6). 
>
> The host itself has openldap-server 2.6 as a service. The host's interface is igb0 with
> assigned ULA. JAILs (around eight jails) are sharing their vnet interfaces via a bridge with
> the same physical device as the host (igb0). After a while (the time elapsed is unspecific)
> the jail is unable to contact the host via IPv6: neither UDP, TCP nor ICMP sent from the JAIL
> is reaching the host. IPv4 is working like a charme! No problems there.
>
> When pinging the Jail from the main host via ping -6, the jail is responding! After the first
> ping -6, the jail now is able to ping -6 the main host.
>
> After a fresh reboot, the problem is not present and occurs after a while and it seems to
> happen first to very active jails.
>
> Kind regards,
>
> oh
>
>
> -- 
> O. Hartmann
>

Hello,

This behavior might be caused by IPFW blocking some IPv6 neighbor discovery/advertisement 
messages.
After some time, the link layer addresses of the IPv6 neighbors in the NDP cache may expire, making
 the associated IPv6 addresses inaccessible.
Do your IPFW rules allow ICMPv6 messages to and from IPv6 multicast addresses?

Regards.