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IPv6 ICMP multicast response - FreeBSD

Hi, By default, FreeBSD does not reply to ICMP multicast echo requests. For IPv4 this behaviour can be changed with sysctl net.inet.icmp.bmcastecho=0|1 Is there a similar control for IPv6? Thank you, Martin...

  1. #1

    Default IPv6 ICMP multicast response

    Hi,

    By default, FreeBSD does not reply to ICMP multicast echo requests. For IPv4 this behaviour
    can be changed with

    sysctl net.inet.icmp.bmcastecho=0|1

    Is there a similar control for IPv6?

    Thank you,

    Martin



    Martin Guest

  2. #2

    Default Re: IPv6 ICMP multicast response

    "Martin Petraschek" <at> writes:
     

    No. That would violate RFC 2463, section 2.4(e.2).
    As well as being a bad idea.

    If you need it for some custom application that won't be
    connected to the Internet, you can hack the source.
    Lowell Guest

  3. #3

    Default Re: IPv6 ICMP multicast response

    On 07 Apr 2005 09:30:29 -0400, Lowell Gilbert wrote:
     
    >
    >No. That would violate RFC 2463, section 2.4(e.2).
    >As well as being a bad idea.[/ref]

    The section you are referencing in RFC 2463 is concerning ICMP
    ERROR messages. Echo requests/responses are informational
    messages, therefore this section does not apply.

    The same RFC 2463, section 4.2 states:

    An Echo Reply SHOULD be sent in response to an Echo
    Request message sent to an IPv6 multicast address. The
    source address of the reply MUST be a unicast address
    belonging to the interface on which the multicast Echo Request
    message was received.

    Therefore, the OS _should_ respond to a multicast echo request!

    Martin



    Martin Guest

  4. #4

    Default Re: IPv6 ICMP multicast response

    "Martin Petraschek" <at> writes:
     

    Ah. You're right; I was thinking about error handling because that's
    the code I happened to be working with this morning. I was looking at
    the error handling code, as well, so when I said it was impossible I
    may have been wrong also. [The ICMP6_ECHO_REQUEST handling in
    icmp6_input() doesn't do any special handling for multicast at all, so
    I don't see why it doesn't Just Work.]

    Sorry for not paying enough attention to the question.
    Lowell Guest

  5. #5

    Default Re: IPv6 ICMP multicast response

    On 07 Apr 2005 10:29:07 -0400, Lowell Gilbert wrote:
     
    >
    >Ah. You're right; I was thinking about error handling because that's
    >the code I happened to be working with this morning. I was looking at
    >the error handling code, as well, so when I said it was impossible I
    >may have been wrong also. [The ICMP6_ECHO_REQUEST handling in
    >icmp6_input() doesn't do any special handling for multicast at all, so
    >I don't see why it doesn't Just Work.]
    >
    >Sorry for not paying enough attention to the question.[/ref]

    No problem.

    Anyway, because of your reply I double checked my setup and found out
    that FreeBSD does indeed answer to multicast ping requests. There just
    does not seem to be a sysctl switch to turn off this behaviour (as there is for
    IPv4).

    Thank you,

    Martin



    Martin Guest

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