[clug] Problem getting a working IPv6 connection

Craig Small csmall at enc.com.au
Fri Feb 1 23:01:27 MST 2013

On Sat, Feb 02, 2013 at 02:04:55PM +1100, Simon Fowler wrote:
> int. +------+ eth +-----+ adsl +---+
> -----|Server|-----|modem|------|ISP|
> net  +------+     +-----+      +---+
>         |          PPPoE         |
>         +- - - - - - - - - - - - +
Are you sure you're pinging using the global address and not the link
address?  Also use the -n flag with ping6 as it sometimes has problems 
reverse resolving.

I have a gogo/gw6c tunnel but the idea is much the same. I have a
"tunnel" address of /128 and a "LAN" address of /64

ip -f inet6 addr show  | grep global
    inet6 2001:44b8:62:180::1/64 scope global 
    inet6 2001:44b8:61::6f/128 scope global 

The first being the LAN address, the second being my tunnel address.
Your addresses should be 2001:44b8:something as you use Internode too.
If you see your pings with addresses with things like fe80:whatever then
thats a link local address, its not going to go anywhwere.

Then try (you will have to replace the addresses with yours):
 ping6 -n 2001:44b8:61::6f  
   this is your tunnel address, failure means your tunnel is messed up
 ping6 -n 2001:44b8:61::6e  
   one less than your tunnel, failure means the tunnel is messed up
 ping6 -I 2001:44b8:62:180::1 -n 2001:44b8:61::6e
   -I eth0 didn't work for me (used tun address).
   ping same as before, but using source address of your LAN. failure
   means most likely YOUR end is messed up, ip6tables or forwarding
 ping6 www.internode.on.net
   pinging from your tunnel to beyond, failure often means your routing
   (route 2000::/3 via tun) is wrong
 ping6 -I 2001:44b8:62:180::1 -n www.internode.on.net
   ping from your LAN to beyond, failure is funky filters on your end
   OR their return routing is wrong.

All the time you are doing this, you should have a tshark/tcpdump on
your tunnel interface.
  tshark -i tun icmp6

mtr -6 is another fine tool for checking where its dying, its not that
good for the what though.

 - Craig
Craig Small VK2XLZ   http://enc.com.au/          csmall at : enc.com.au
Debian GNU/Linux     http://www.debian.org/      csmall at : debian.org
GPG fingerprint:     5D2F B320 B825 D939 04D2  0519 3938 F96B DF50 FEA5

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