Re: point2point network interfaces cannot receive ipv6 packets

[Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>]

Hi,

On 2015/04/03 16:14, Takahiro HAYASHI wrote:
> It seems that IFF_POINTTOPOINT interfaces like tun and gif cannot
> receive ipv6 packets.
> This occurs on NetBSD/amd64 -current since Feb 27 2015.
> 
> For example, establishing gif tunnnel between 2 hosts.
> 
> [host1] <---> [host2]
> 192.168.0.1   192.168.0.2  ipv4 address of real interface
> fd00::1       fd00::2      gif address
> 
> When I ping6, a host can send ICMPv6 ECHO(128), but the other host
> returns ICMPv6 DST_UNREACH(1) code UNREACH_ADDR(3) to pinging host.

I think the reason of this issue is below commit:
    http://www.nerv.org/netbsd/?q=id:20150226T095446Z.75354d997222ae09acc944ba1c6cf573c3ea724b

This commit changes the route entry for gif as describe below
========== before ==========
Internet6:
Destination                        Gateway                        Flags    Refs      Use    Mtu Interface
fd00::2                            link#13                        UHL         0        0      -  lo0
========== before ==========
========== after ==========
Internet6:
Destination                        Gateway                        Flags    Refs      Use    Mtu Interface
fd00::2                            fd00::2                        UH          -        -      -  gif0
========== after ==========

This route change caused the function flow change in ip6_input(), in
paticular the below line
    http://nxr.netbsd.org/xref/src/sys/netinet6/ip6_input.c#497
After above commit, this statement become false, and then, the packets
is discarded through line#565.

I found the above reason, however I have no idea to fix this issue...

> roy@n.o
Could you comment about this issue?


Thanks,

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Device Engineering Section,
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Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>