Re: [gentoo-user] ipv6 problem with ping6

[Michael Mol <mikemol@gmail.com>]

Paul Hartman wrote:
> On Fri, Jan 6, 2012 at 3:09 PM, Michael Mol <mikemol@gmail.com> wrote:
>> Grant Edwards wrote:
>>> I've enabled ipv6 support in my kernel and it appears to be working on
>>> the "lo" interface:
>>>
>>>    # ip -6 addr show lo
>>>
>>>    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436
>>>        inet6 ::1/128 scope host
>>>           valid_lft forever preferred_lft forever
>>>
>>>    # ping6 -c3 ::1
>>>
>>>    PING ::1(::1) 56 data bytes
>>>    64 bytes from ::1: icmp_seq=1 ttl=64 time=0.022 ms
>>>    64 bytes from ::1: icmp_seq=2 ttl=64 time=0.021 ms
>>>    64 bytes from ::1: icmp_seq=3 ttl=64 time=0.021 ms
>>>
>>>    --- ::1 ping statistics ---
>>>    3 packets transmitted, 3 received, 0% packet loss, time 1998ms
>>>    rtt min/avg/max/mdev = 0.021/0.021/0.022/0.003 ms
>>>
>>> And the other interfaces all have link-local addresses:
>>>
>>>    # ip -6 addr show eth1
>>>    3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
>>>        inet6 fe80::216:17ff:fe84:a7b3/64 scope link
>>>           valid_lft forever preferred_lft forever
>>>
>>> But I can't ping6 any of the "real" interfaces (or any external
>>> address):
>>>
>>>    # ping6 -c3 fe80::216:17ff:fe84:a7b3
>>>
>>>    connect: Invalid argument
>>>
>>> Why can I ping "lo" at ::1 and not "eth1" at fe80::216:17ff:fe84:a7b3?
>>>
>>> I'm guessing there might other packages I have to re-emerge with the
>>> ipv6 use flag. But, I do not want to rebuild everything capable of
>>> supporting ipv6, since there are only a few selected programs that
>>> I'll be using with ipv6.  I thought I might have to rebuild glibc, but
>>> it doens't list ipv6 as one of it's use flags.
>>>
>>> Any hints?
>>>
>>
>> ping6 -c3 fe80::216:17ff:fe84:a7b3%eth0
>>
>> Link-local addresses are only valid at the link-level scope, and you
>> have to specify which link you're referring to. Global-scope addresses
>> don't have the same limitation.
> 
> and to see the scope you can view the output of ifconfig, see
> something in there like this next to each address:
> 
> scopeid 0x0<global>
> scopeid 0x20<link>
> 

Likewise, if you use iproute2:

shortcircuit:0@prgmr2.rosettacode.org~
Fri Jan 06 09:24 PM
!502 #2 j0 ?0 $ ip -6 addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 2605:2700:0:3::4713:91bf/64 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::a800:ff:fe13:91bf/64 scope link
       valid_lft forever preferred_lft forever


The phrase "scope global" or "scope link" appears after each of my IPv6
addresses on that interface.