Hello, I set up my tunnel on arch-linux, using ip on kernel 2.6.3 I use the following script to start it: #!/bin/bash #sync the time to be sure heartbeat works /usr/bin/rdate -s time.xs4all.nl #create tunnel /usr/sbin/ip tunnel add sixxs mode sit local 217.122.24.27 remote 213.204.193.2 #bring tunnel up /usr/sbin/ip link set sixxs up #fix MTU and TTL /usr/sbin/ip link set mtu 1280 dev sixxs /usr/sbin/ip tunnel change sixxs ttl 64 #config ipv6 endpoint, was /64 /usr/sbin/ip -6 addr add 2001:960:2:15d::2/64 dev sixxs #route ipv6 traffic /usr/sbin/ip -6 ro add default via 2001:960:2:15d::1 dev sixxs #start heartbeat monitor /usr/local/bin/heartbeat-client /usr/local/etc/heartbeat.conf However it doesnt work. tcpdump shows the HB being send. ifconfig dump: sixxs Link encap:UNSPEC HWaddr D9-7A-18-1B-00-00-00-00-00-00-00-00-00-00-00-00 inet6 addr: fe80::d97a:181b/128 Scope:Link inet6 addr: 2001:960:2:15d::2/64 Scope:Global UP POINTOPOINT RUNNING NOARP MTU:1280 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) route is also correctly setup as tcpdump shows pings going trough the tunnel. However no replies are received, 100% loss. Perhaps the firewall interferes. I opened the outgoing port for the heartbeat protocol. I also tried without a firewall to no avail, I got the same results. Any clues?