Router. eth0 is external, with the 6to4 bound to it. eth1 is internal: 2: eth0: mtu 1500 qlen 1000 inet6 fe80::200:24ff:fec8:dc50/64 scope link valid_lft forever preferred_lft forever 3: eth1: mtu 1500 qlen 1000 inet6 2002:d976:2d51:2:0:24ff:fec8:dc51/48 scope global valid_lft forever preferred_lft forever inet6 fe80::200:24ff:fec8:dc51/64 scope link valid_lft forever preferred_lft forever 7: 6to4@NONE: mtu 1480 inet6 2002:d976:2d51::1/16 scope global valid_lft forever preferred_lft forever inet6 ::217.118.45.81/128 scope global valid_lft forever preferred_lft forever Internal host: 2: eth0: mtu 1500 qlen 1000 inet6 2002:d976:2d51:2:20e:cff:fec3:20c2/64 scope global dynamic valid_lft 2591756sec preferred_lft 604556sec inet6 fe80::20e:cff:fec3:20c2/64 scope link valid_lft forever preferred_lft forever Internal host routing table: $ ip -6 route show 2002::/16 dev eth0 proto kernel metric 256 expires 2592074sec mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev eth0 metric 256 expires 20480319sec mtu 1500 advmss 1440 hoplimit 4294967295 ff00::/8 dev eth0 metric 256 expires 20480319sec mtu 1500 advmss 1440 hoplimit 4294967295 default via fe80::200:24ff:fec8:dc51 dev eth0 proto kernel metric 1024 expires 1712sec mtu 1500 advmss 1440 hoplimit 64 Router routing table: # ip -6 route show ::/96 via :: dev 6to4 metric 256 expires 21250840sec mtu 1480 advmss 1420 hoplimit 4294967295 2002:d976:2d51:2::/64 dev eth1 metric 256 expires 21334240sec mtu 1500 advmss 1440 hoplimit 4294967295 2002::/16 dev 6to4 metric 256 expires 21251107sec mtu 1480 advmss 1420 hoplimit 4294967295 2002::/16 dev eth1 proto kernel metric 256 expires 2517730sec mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev eth0 metric 256 expires 19582370sec mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev eth1 metric 256 expires 19582370sec mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev 6to4 metric 256 expires 21251107sec mtu 1480 advmss 1420 hoplimit 4294967295 ff00::/8 dev eth0 metric 256 expires 19582370sec mtu 1500 advmss 1440 hoplimit 4294967295 ff00::/8 dev eth1 metric 256 expires 19582370sec mtu 1500 advmss 1440 hoplimit 4294967295 ff00::/8 dev 6to4 metric 256 expires 21251107sec mtu 1480 advmss 1420 hoplimit 4294967295 default via ::192.88.99.1 dev 6to4 metric 1026 expires 21251111sec mtu 1480 advmss 1420 hoplimit 4294967295