Ping IPv6? - Ubuntu

This is a discussion on Ping IPv6? - Ubuntu ; ~$ping6 fe80::20c:76ff:fe81:1 connect: Invalid argument Huh? Silly question... how do I ping an IPv6 address in Ubuntu Hardy? Any ideas? This does seem like a really stupid question but..... "Invalid argument." Is my IP address formatted incorrectly? It looks right ...

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  1. Ping IPv6?

    ~$ping6 fe80::20c:76ff:fe81:1
    connect: Invalid argument

    Huh? Silly question... how do I ping an IPv6 address in Ubuntu Hardy?
    Any ideas? This does seem like a really stupid question but.....
    "Invalid argument."

    Is my IP address formatted incorrectly? It looks right to me.

    ~$ ping6 server
    unknown host

    Oh dear.

  2. Re: Ping IPv6?

    On Tue, 03 Jun 2008 10:27:12 +0100, Cork Soaker rearranged some electrons
    to say:

    > ~$ping6 fe80::20c:76ff:fe81:1
    > connect: Invalid argument
    >
    > Huh? Silly question... how do I ping an IPv6 address in Ubuntu Hardy?
    > Any ideas? This does seem like a really stupid question but.....
    > "Invalid argument."
    >
    > Is my IP address formatted incorrectly? It looks right to me.
    >
    > ~$ ping6 server
    > unknown host
    >
    > Oh dear.


    What you wrote means:

    fe80:0:0:0:20c:76ff:fe81:1

    Is that what you meant? (ie. did you put the double colon in the right
    place?)


  3. Re: Ping IPv6?

    david wrote:
    > On Tue, 03 Jun 2008 10:27:12 +0100, Cork Soaker rearranged some electrons
    > to say:
    >
    >> ~$ping6 fe80::20c:76ff:fe81:1
    >> connect: Invalid argument
    >>
    >> Huh? Silly question... how do I ping an IPv6 address in Ubuntu Hardy?
    >> Any ideas? This does seem like a really stupid question but.....
    >> "Invalid argument."
    >>
    >> Is my IP address formatted incorrectly? It looks right to me.
    >>
    >> ~$ ping6 server
    >> unknown host
    >>
    >> Oh dear.

    >
    > What you wrote means:
    >
    > fe80:0:0:0:20c:76ff:fe81:1
    >
    > Is that what you meant? (ie. did you put the double colon in the right
    > place?)
    >


    Yes, that's correct. This is the IP of another machine on the same
    (physically connected) network.

  4. Re: Ping IPv6?

    Hello,

    Cork Soaker a écrit :
    > ~$ping6 fe80::20c:76ff:fe81:1
    > connect: Invalid argument


    This is a "link local" address, so you must specify which interface to
    use because such an address may be reachable on any interface. For the
    ping6 command, use the -I option, e.g. :

    $ ping6 -I eth0 fe80::20c:76ff:fe81:1

    With other programs, you can use the syntax
    % as the
    destination, e.g. :

    $ telnet fe80::20c:76ff:fe81:1%eth0

    But it is best to use global or unique local unicast addresses.

  5. Re: Ping IPv6?

    Pascal Hambourg wrote:
    > Hello,
    >
    > Cork Soaker a écrit :
    >> ~$ping6 fe80::20c:76ff:fe81:1
    >> connect: Invalid argument

    >
    > This is a "link local" address, so you must specify which interface to
    > use because such an address may be reachable on any interface. For the
    > ping6 command, use the -I option, e.g. :
    >
    > $ ping6 -I eth0 fe80::20c:76ff:fe81:1
    >
    > With other programs, you can use the syntax
    % as the
    > destination, e.g. :
    >
    > $ telnet fe80::20c:76ff:fe81:1%eth0
    >
    > But it is best to use global or unique local unicast addresses.



    That's it! :-D

    ping6 worked fine with %eth0 appended to the end, I'm very happy to say. :-)

    I really should have figured this out from my Windows days, but alas, I
    did not!

    However, given that the PC only had two IPv6 addresses,
    fe80::20c:76ff:fe81:1 and ::1, I would have hoped the stack would be
    able to figure out where to send the ping (as the fe80 address would be
    unreachable on lo).

    I am, of course, aware of the problem with multiple NICs and link-local
    addresses, but this shouldn't affect desktop users, and of course MID
    and mobile-IPv6 users, as most will only have one network card, so maybe
    this needs to be resolved before stupid Windozers start crying about the
    "complexity" of Linux networking?

    Thanks again Pascal.

  6. Re: Ping IPv6?

    Cork Soaker a écrit :
    >
    > However, given that the PC only had two IPv6 addresses,
    > fe80::20c:76ff:fe81:1 and ::1, I would have hoped the stack would be
    > able to figure out where to send the ping (as the fe80 address would be
    > unreachable on lo).


    This makes sense, but I guess the routing code in the kernel has
    hardcoded that link local destinations must specify the interface,
    whether the link local route in the routing table is unique or not.

    > I am, of course, aware of the problem with multiple NICs and link-local
    > addresses, but this shouldn't affect desktop users, and of course MID
    > and mobile-IPv6 users, as most will only have one network card, so maybe
    > this needs to be resolved before stupid Windozers start crying about the
    > "complexity" of Linux networking?


    As I wrote, my opinion is that the users should not use link local
    addresses, so it not that much an issue.

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