How to setup tspc ipv6-ipv4 tunnel thru NAT on ubuntu linux

sudo apt-get install tspc
sudo vim /etc/tsp/tspc.conf

#Find the userid line and enter your useid for freenet6, then find the passwd line and enter your #password you set, then set the server as broker.freenet6.net
#Like this:
userid=your-name
server=broker.freenet6.net
passwd=your-password

server=montreal.freenet6.net
#or
server=amsterdam.freenet6.net       

try :
tunnel_mode=v6anyv4
#or
tunnel_mode=v6udpv4

retry_delay=3
keepalive=yes
keepalive_interval=1
if_prefix=eth0
----- 8<  ----- 8<  -----

sudo /etc/init.d/tspc stop
sudo /etc/init.d/tspc start

check ipv6 connection :
ping6 -n ipv6.google.com