No IPv6 connectivity on the router behind the NAT

Mazzy

12/10/23, 9:38 AM

I have the following scenario. My ISP does not provide IPv6. As common practice, I've created a SIT tunnel with Hurricane.

My network is the following.

  WAN (eth0)
------------ router A 
                |eth1
                |      WAN (192.168.88.250)
                |-------------| router B
                                   | eth0
                                   |--------------- PC (192.168.10.5/24)

The SIT tunnel is created in the router A.

If I connect any device to the router A, I have successfully IPv6 connectivity. The WAN interface of the router B has set a static IPv6 address and it is connected to the router A.

Inside the router B I can have IPv6 connectivity. In fact if I ping any external IPv6 address from the router, the traffic goes out perfectly from the Router A.

Then I have tried to create a network in the router B (192.168.10.0/24) with different IPv6 address block. One /64 taken out from the /48 block address that Hurricane provide.

At this point I do not have connectivity to IPv6 if I connect a device under 192.168.10.1

The WAN port of the router B is set to have a static IP address and gateway in the ipv6 network of the router A. This give me successfully connectivity.

What I would expect is that since I have in the router B, as default IPv6 route the following

default via xxxx:xxxx:6f:14:: dev eth8 proto static metric 1024 pref medium

where xxxx:xxxx:6f:14:: is the gateway set it up at the WAN interface of the router B

all IPv6 traffic generated inside the router B should go out the WAN interface.

The problem is that I've sniffed the traffic generated from the router B at the router B Sit interface and I cannot see coming anything.

117

1 + 5

ipv6

tunnel

Mazzy

12/10/23, 12:02 PM

From my last packet sniffing, I have found out that the traffic, generated from a machine plugged int the router B having IPv6, reaches successfully the SIT tunnel. The only problem now is to understand why there is no reply.

Mazzy

12/10/23, 12:05 PM

I've noticed that looking at the SIT tunnel I get the ICMP response. so the problem is in the last mile. there is no IPv6 packet forward to the WAN interface.

vidarlo

12/10/23, 2:04 PM

Why are you talking about IPv4 addresses if the issue is IPv6? Show us how your IPv6 is configured, *NOT* the IPv4 setup.

Mazzy

12/10/23, 7:03 PM

Yes that's true. The question misses ipv6 addresses because mine are global unicast that I've preferred to not share.

vidarlo

12/10/23, 7:15 PM

Replace your prefix with the documentation subnet (2001:db8::/32), so that we can see the relationship then.

Score:0

Server

Mazzy

12/10/23, 12:34 PM

The problem is that the Router A does not have any knowledge of the IPv6 address block so I had to put there a route to forward traffic to the WAN router interface.

+ 0

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: No IPv6 connectivity on the router behind the NAT

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