If I ping6 external ipv6 hostnames or addresses (e.g. ipv6.google.com) it works, but if I try to ping6 an ipv6 hostname or address it doesn't work. If I ping the same address from a windows machine on the LAN, it works. Why would this happen?

Target Machines are running Windows 7 or Server 2008 R2 and Teredo My machine is running Ubuntu 10.04 and Miredo

  • Please provide examples of how you are pinging the machine. – Jeremy Visser Feb 21 '11 at 11:57

You might want to try pinging the link-local address to narrow it down between a firewall or other networking problem between the two hosts, and a Teredo problem. I have heard of problems where, when using Teredo-based IPv6 addresses, you cannot ping other machines on your own subnet. For example, I can ping a Windows 7 machine on the same network as my Ubuntu machine by doing this (on my Ubuntu machine):

$ ping6 -c 5 -I eth0 fe80::e1ce:694a:18c0:6530

Note, the -I argument is important when pinging a link-local address because otherwise the host OS has no way to know which link-local interface you're talking about. (for all it knows, you want to use the Teredo interface, or the loopback interface, for example.)

  • It works if I add the -I eth0 argument! Thanks! I wonder why ping6 wouldn't pick eth0 first though just like ping does – David Feb 22 '11 at 6:33
  • @David, it can't pick eth0 because the address alone is not enough information - all interfaces have a link-local address in the fe80::/64 subnet. if you have a global unicast address assigned to the interface, the per-interface distinction would not be needed. If the address starts with fe80::, it is a link-local address and requires an interface to "scope" the request. Sometimes you'll see the scope written after the address, such as fe80::1%eth0. (all that said; I think you're right in that if there was only one non-loopback interface, the system should pick that one.) – mpontillo Feb 22 '11 at 6:42

I'm not sure exactly what you're trying to ping, but if you're trying to ping a Windows machine then Windows Firewall may be blocking the ping request - disable it and it should work.

  • 1
    Windows firewall can't be the problem because I can ping from other windows machines, just not from my Ubuntu machine – David Feb 22 '11 at 6:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.