Hi I have an Ubuntu Firewall with a static IP and an IPv6 Tunnel to Sixxs. Worked fine till about 3 days ago. All packages sent to the Firewall via IPv6 work fine. Packages from the FW don't reach there destination. If I use tcpdump -ni eth0 host 194.1.163.40 i can see the sent packages leaving my FW. But they don't get to destination. (also ping from Sixxs looks like this.) 10:37:47.169435 IP 194.1.163.40 > 82.192.250.179: IP6 2001:8a8:21:5:216:3eff:fec1:413 > 2001:41e0:ff00:33::2: ICMP6, echo request, seq 1, length 64 10:37:47.169775 IP 82.192.250.179 > 194.1.163.40: IP6 2001:41e0:ff00:33::2 > 2001:8a8:21:5:216:3eff:fec1:413: ICMP6, echo reply, seq 1, length 64 In the logfiles i could not find any warnings or errors. The Firewall does not block any packages to the PoP and IPv6 tables have no rules and accept everything. Any Ideas what could be the Problem??? I'm a little out of ideas. My Config: Ubuntu 6.04 LTS /etc/network/interfaces: auto sixxs iface sixxs inet6 v4tunnel address 2001:41e0:ff00:33::2 netmask 64 endpoint 194.1.163.40 ttl 64 up ip link set mtu 1280 dev sixxs up ip route add default via 2001:41e0:ff00:33::1 dev sixxs Thanks for your effort. Noah