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

[dmb%yenn.ulegend.net@localhost]

>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
>Fix:
Dunno yet.

>Unformatted:
 Sources from Jun 13 2017, kernel compiled with altq, but it shouldn't matter.