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I am trying to setup IPv6 linux router. My setup is as shown below.

HOST1 (eth0) -----(eth0) ROUTER (eth1) ------ (eth0) HOST2

I am trying to ping HOST2 from HOST1. I am actually seeing packets until eth0 interface of ROUTER. But ROUTER is not forwarding those packets via eth1 to reach eth0.

I enabled IPV6 forwarding in router. Is there anything I am still missing out?

Check the ipaddresses of each interface

HOST1 (eth0) - link local address
ROUTER (eth0) - link local address
ROUTER (eth1) - 2400:ab::1
HOST2 (eth0) - 2400:ab::2
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Are you testing with fe80:: addresses? – grawity Sep 19 '11 at 11:06
Not exactly but I am trying to reach from a host with link local address to host2 with global address – codingfreak Sep 20 '11 at 7:10

Difficult to say without more details...

  1. (Even if it sounds ridiculous): Be sure to use an IPv6-ping (Linux: ping6)

  2. Check if a firewall is in place. If yes: Check if packet forwarding for IPv6 packets is allowed (for TCP, UDP and ICMP6 packets)

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1. I am using ping6 to ping the other end 2. I flushed out all the rules in ip6tables so default option would be forward right ? .. – codingfreak Sep 20 '11 at 7:05
Not sure if flushing the tables resets the default policy and I have no Linux box available right now. Just list the rules and check or explicitly allow forwarding with ip6tables -P FORWARD ACCEPT. – ktf Sep 22 '11 at 14:32

Link-local addresses are local to the link (an Ethernet broadcast domain), and packets with such addresses are forbidden from being forwarded by routers.

Besides, such addresses are always in the same fe80::/10 prefix – for both eth0 and eth1 – so even if the packets were forwarded, the replies would go to the wrong location.

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