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A host who has private IPv4 address can communicate with IPv6 host globaly by 6to4 tunnel

Hello all,

I have a idea about communication method with 6to4 tunnel.

Generally, we think a host who has private IPv4 address(because it is behind NAT device) can not communicate with IPv6 host globally by tunneling(6to4, config tunnel ..) But there is a way using 6to4 tunnel.

When we config 6to4 config on a host(for example windows2000 station) we assign the hosts IPv4 address to the hosts 6to4 address(next to 2002:). And we know the hosts IPv4 address shoud be public IPv4 address.

But, if we use the public IPv4 address which is on NAT devices external interface to make the hosts 6to4 address, the host can communicate with IPv6 host globally using 6to4 tunnel and relay router. Following are do list.

1.       Map the NAT devices public address(select one) to the hosts private address(configure on the NAT)

2.       On the NAT device, make a policy which permit incomming traffic which has protocol number 41 to the hosts private address

3.       Change the NAT devices public IPv4 address(which you selected) to hex. format.

4.       Configure the hosts 6to4 address using upper hex.

5.       Add route table for 2002 traffic to tunnel interface, and ::/0 to relay router(relay router is provided by some orgnization)


And then,...try ping6 to any IPv6 address. following is the result of my own test.


C:\>ping6 6to4.ipv6.fh-regensburg.de

Pinging 6to4.ipv6.fh-regensburg.de [2002:c25f:6cbf:1::1] with 32 bytes of data:


Reply from 2002:c25f:6cbf:1::1: bytes=32 time=330ms

Reply from 2002:c25f:6cbf:1::1: bytes=32 time=329ms

Reply from 2002:c25f:6cbf:1::1: bytes=32 time=329ms



C:\>ping6 www.kame.net


Pinging orange.kame.net [2001:200:0:8002:203:47ff:fea5:3085] with 32 bytes of data:


Reply from 2001:200:0:8002:203:47ff:fea5:3085: bytes=32 time=117ms

Reply from 2001:200:0:8002:203:47ff:fea5:3085: bytes=32 time=72ms

Reply from 2001:200:0:8002:203:47ff:fea5:3085: bytes=32 time=68ms

Reply from 2001:200:0:8002:203:47ff:fea5:3085: bytes=32 time=71ms




Following is my computers IP config




Windows 2000 IP Configuration


Ethernet adapter :


Connection-specific DNS Suffix . :

IP Address. . . . . . . . . . . . :

Subnet Mask . . . . . . . . . . . :

Default Gateway . . . . . . . . . :




as you know is private address !!

Try it.


Jisuek. Lim