Re: kern/52313: NetBSD 8.0_BETA issues with ircd, ipfilter, and v6only=0 set

[Ryota Ozaki <ozaki-r%netbsd.org@localhost>]

On Mon, Jun 19, 2017 at 4:15 AM,  <dmb%yenn.ulegend.net@localhost> wrote:
>>Number:         52313
>>Category:       kern
>>Synopsis:       NetBSD 8.0_BETA has issues with ircd (IRCnet one) + ipfilter + v6only=0 set
>>Confidential:   no
>>Severity:       serious
>>Priority:       medium
>>Responsible:    kern-bug-people
>>State:          open
>>Class:          sw-bug
>>Submitter-Id:   net
>>Arrival-Date:   Sun Jun 18 19:15:00 +0000 2017
>>Originator:     Dominik Bialy
>>Release:        NetBSD 8.0_BETA
>>Organization:
> Underlegend Networks
>>Environment:
> System: NetBSD yenn 8.0_BETA NetBSD 8.0_BETA (YENN) #2: Thu Jun 15 05:53:36 UTC 2017 builds@yenn:/var/obj/sys/arch/amd64/compile/YENN amd64
> Architecture: x86_64
> Machine: amd64
>>Description:
> When using an application which needs v6only=0 -- ircd (IRCnet one) --
> all connections on IPv4 are being reset.  There is ipfilter set.
> I was trying to pass all on it, but effect is the same.  I didn't try
> to disable ipfilter.  I'm not sure wether it's the ircd bug, or some
> bug/misfeature of NetBSD or ipfilter in it.
>
> I didn't test any other v6only=0 apps.
>
> PS: I can't restart the machine for now, so I can't test any fixes...
>>How-To-Repeat:
> Try to run IRCnet ircd with v6only=0 + ipfilter, and connecting using IPv4

Is this a regression? Did the same setup work on NetBSD 7 or earlier?

What exactly happens on "all connections on IPv4 are being reset"?
- (I assume ircd is a server)
- Anyone cannot connect to the ircd? Or can connect but disconnect
  for some reason?
- Where packets reach? ircd? ipfilter? the NIC?

Thanks,
  ozaki-r