Routing IPv6 over tun0 (PPPoE) issue

[Gary Palmer]

Hi,

I'm trying to set up IPv6 now that my ISP has decided to start offering
native V6.  I've been using a tunnelbroker setup until now.  I have

ipv6_gateway_enable="YES"
ipv6_cpe_wanif="tun0"

set in /etc/rc.conf and PPP has "enable ipv6cp" set.  OS is 
FreeBSD 9.3-RELEASE-p21

When the system boots up I get

tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1492
        options=80000<LINKSTATE>
        inet6 fe80::200:24ff:fec9:5bbc%tun0 prefixlen 64 scopeid 0xa 
        inet 217.155.53.182 --> 62.3.83.6 netmask 0xffffffff 
        inet6 xxxx:yyyy:zzzz:2:200:24ff:fec9:5bbc prefixlen 64 autoconf 
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
        Opened by PID 1038

Routing is

# netstat -nr -f inet6
Routing tables

Internet6:
Destination                       Gateway                       Flags      Netif Expire
::/96                             ::1                           UGRS        lo0 =>
default                           fe80::230:88ff:fe16:ec4f%tun0 UG         tun0
::1                               link#9                        UH          lo0
<etc>


traceroute6 www.freebsd.org works when the traffic is sourced from the
tun0 interface IP

# traceroute6 www.freebsd.org
traceroute6 to wfe0.ysv.freebsd.org (2001:1900:2254:206a::50:0) from xxxx:yyyy:zzzz:2:200:24ff:fec9:5bbc, 64 hops max, 12 byte packets
 1  xxxx:yyyy::3:0:0:2  29.030 ms  28.782 ms  29.205 ms
 2  xxxx:yyyy:0:301::  29.414 ms  28.967 ms  29.232 ms
 3  xxxx:yyyy:0:4::1  28.750 ms  29.253 ms  82.200 ms
 4  xxxx:yyyy:0:3::1  36.181 ms  35.352 ms  35.330 ms
<etc>

However if I configure other IPs on other interfaces from the netblock that
has been delegated to me and either source the traffic from those IPs or
try the traceroute from another computer using IPs in that netblock, I
don't even see the traffic leaving tun0 with tcpdump, let alone get any
replies.

I do have PF running, but all my rules that stop traffic are logged
and I don't see any hits in pflog.  Also, I tried turning pf off once
and didn't have any luck either, although I must admit I didn't leave it
off long for obvious reasons, so maybe I missed something in my test.

Any ideas?  Is it because I am routing to a link local address rather
than a routable IP?  Unfortunately the returned packets from the first
hop aren't in the subnet I was given for the link so I can't use that
as a gateway.

Thanks,

Gary