gif interface not passing IPv6 packets

[Matt Smith]

On 26 September 2011 15:21, Gary Palmer <gpalmer at freebsd.org> wrote:
> Smells like a routing table problem or similar configuration problem.
> On my tunnel endpoint, admitedly running 7.4 not 8.x or head, pings
> to the LOCAL endpoint of the gif0 tunnel go over lo0, not the external
> interface (gif0).  I believe that is true for all IPv4 or IPv6 traffic.

Interesting. You could be right then. But I still don't understand
what could have changed as the rc.conf configuration for this is
identical to what it was before the power cut. The deprecated part
just makes the outgoing source address algorithm favour the vr0
address, but the same happens no matter if I include that or not.

ipv6_enable="YES"
ipv6_ifconfig_vr0="2a01:348:294::1 prefixlen 64"
gif_interfaces="gif0"
gifconfig_gif0="192.168.1.2 77.75.104.126"
ipv6_ifconfig_gif0="2a01:348:6:45c::2 2a01:348:6:45c::1 prefixlen 128
deprecated"
ipv6_defaultrouter="2a01:348:6:45c::1"
ipv6_gateway_enable="YES"
rtadvd_enable="YES"
rtadvd_interfaces="vr0"

Which produces:

vr0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=82808<VLAN_MTU,WOL_UCAST,WOL_MAGIC,LINKSTATE>
        ether 00:40:63:e8:79:3e
        inet 192.168.1.2 netmask 0xffffff00 broadcast 192.168.1.255
        inet6 fe80::240:63ff:fee8:793e%vr0 prefixlen 64 scopeid 0x1
        inet6 2a01:348:294::1 prefixlen 64
        nd6 options=3<PERFORMNUD,ACCEPT_RTADV>
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active
gif0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1280
        tunnel inet 192.168.1.2 --> 77.75.104.126
        inet6 fe80::240:63ff:fee8:793e%gif0 prefixlen 64 scopeid 0x5
        inet6 2a01:348:6:45c::2 --> 2a01:348:6:45c::1 prefixlen 128 deprecated
        nd6 options=3<PERFORMNUD,ACCEPT_RTADV>
        options=1<ACCEPT_REV_ETHIP_VER>

Destination                       Gateway                       Flags
    Netif Expire
::/96                             ::1                           UGRS
     lo0 =>
default                           2a01:348:6:45c::1             UGS        gif0
::1                               ::1                           UH          lo0
::ffff:0.0.0.0/96                 ::1                           UGRS        lo0
2a01:348:6:45c::1                 2a01:348:6:45c::2             UH         gif0
2a01:348:294::/64                 link#1                        U           vr0
2a01:348:294::1                   link#1                        UHS         lo0

The interesting thing is I've just got the routing table from my
friends working server with similar configuration except his is just a
tunnel without any subnet and his has this:

Destination                       Gateway                       Flags
    Netif Expire
::/96                             ::1                           UGRS
     lo0 =>
default                           2a01:348:6:45d::1             UGS        gif0
::1                               ::1                           UHL         lo0
::ffff:0.0.0.0/96                 ::1                           UGRS        lo0
2a01:348:6:45d::1                 link#3                        UHL        gif0
2a01:348:6:45d::2                 link#3                        UHL         lo0

I'm wondering why there are clearly significant differences here. If
my configuration didn't work before then I can accept that I've
screwed up in some way but it's worked for months so I don't
understand what's changed now. Unfortunately I don't know what my
routing table looked like originally when it worked but I'm thinking
for some reason when the box boots it's building the routing table
differently to how it was before now?