I have a Linux router without an ipv6 stack and a Linux host inside the NAT. How do I use iptables to forward 6to4 traffic back and forth between the NAT router and the host and then configure the 6to4 tunnel on the host using the router's public IPv4 address?
This recipe (on the router) gets an ipv6 ping to the host's eth0 but they don't make it onto the tun6to4 interface. Wireshark says "ICMP Destination unreachable (Port unreachable)" as an ipv4 response to the 6to4 ping.
# inbound destination NAT for IPv6 tunnel. ppp0 is router's WAN interface. iptables -t nat -A PREROUTING -i ppp0 -p 41 -j DNAT --to 192.168.1.100 # inbound forwarding for IPv6 tunnel iptables -t filter -A FORWARD -i ppp0 -p 41 -d 192.168.1.100 -j ACCEPT
I am using this script on the Linux host, passing the router's public ip:
#!/bin/bash ### Get the global IPv4 address for your host from the command line: GLOB_IP4=$1 ### Compute the 6TO4 tunnel IPv6 address: GLOB_IP6TO4=$(printf "2002:%02x%02x:%02x%02x::1" $(echo $GLOB_IP4 | tr . ' ')) ### Setup the tunnel ip tunnel add tun6to4 mode sit remote any local $GLOB_IP4 ttl 64 ip link set dev tun6to4 up ip addr add $GLOB_IP6TO4/16 dev tun6to4 ip route add 2000::/3 via ::126.96.36.199 dev tun6to4 metric 1