IPv6 and a local network behind a gateway

[Stefan]

Hi all,

I saw some time ago a similiar question on the mailinglist but the  
relevant config files were on a temporarly server, so I can't  
reconstruct the situation. So I hope someone could say the things a  
second time ;-)

Here is my setup:
I'm running a FreeBSD server behind a DSL-Box (NAT) with one network  
interface. This server is connected with two other workstation  
through a switch. I register by sixxs (a IPv6 service provider).  
After some installation I got my IPv6 connection between  the sixxs  
provider and my FreeBSD server running! I can ping www.kame.net and  
when I go to ww.kame.net with lynx I "can see" the dancing kame. So  
the setup should be fine. I setup rtadvd for the workstations and it  
seems to be ok. The workstations get their IPv6 addresses but I can't  
ping anything outside my LAN.

Summary:
Connecting to the IPv6-world from the FreeBSD-server is OK but I  
don't get any connection from the clients.

Here are the configs:

/etc/rc.conf
ipv6_enable="YES"
ipv6_defaultrouter="2001:6f8:900:612::1%em0"
ipv6_default_interface="gif0"
gif_interfaces="gif0"
gifconfig_gif0="192.168.130.2 212.224.0.189"
ipv6_ifconfig_gif0="2001:6f8:900:612::2 2001:6f8:900:612::1 prefixlen  
128"
ipv6_gateway_enable="YES"
ipv6_ifconfig_em0="2001:6f8:900:612::3 prefixlen 64"
rtadvd_enable="YES"
rtadvd_interfaces="em0"

/etc/rtadvd.conf
em0:\
    :addrs#1:addr="2001:6f8:900:612::":prefixlen#64:tc=ether:

Hardware (FreeBSD server):
one network interface card: em0

Software (FreeBSD server):
default installation with the latest updates

tcpdump from the FreeBSD server when I try to ping6 www.kame.net from  
a client
# tcpdump -ni gif0 icmp6
00:59:36.917672 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 0,  
length 16
00:59:37.922935 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 1,  
length 16
00:59:38.930710 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 2,  
length 16
00:59:39.933212 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 3,  
length 16
00:59:40.938355 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 4,  
length 16
00:59:41.943378 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 5,  
length 16
00:59:42.948514 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 6,  
length 16
00:59:43.953657 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 7,  
length 16
00:59:44.958794 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 8,  
length 16
00:59:45.963937 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 9,  
length 16
00:59:46.969333 IP6 2001:6f8:900:612:211:24ff:fee1:776c >  
2001:200:0:8002:203:47ff:fea5:3085: ICMP6, echo request, seq 10,  
length 16

I don't have an more ideas! I always thought the problem is the  
server behind the NAT but the surfen and ping'ing from the server  
itself is no problem, so I think the problem must be somewhere else?!

Best regards,
Stefan