On Wed, 14 Aug 2002, Matthew Byng-Maddick wrote:
> This shouldn't be on exim-users, but:
>
> On Wed, Aug 14, 2002 at 09:58:33AM +0200, Jan Johansson wrote:
> > > To my knowledge it's a violation of certain
> > > applicable RFC's NOT to return an ICMP echo request
> > Uhm, no. Hosts are definitely not required to return anything. It's
> > recommended, but not required.
>
> | 1122 Requirements for Internet Hosts - Communication Layers. R.
> | Braden, Ed.. October 1989. (Format: TXT=295992 bytes) (Also STD0003)
> | (Status: STANDARD)
>
> S.3.2.2.6 (Page 42)
> | 3.2.2.6 Echo Request/Reply: RFC-792
> |
> | Every host MUST implement an ICMP Echo server function that
> | receives Echo Requests and sends corresponding Echo Replies.
> | A host SHOULD also implement an application-layer interface
> | for sending an Echo Request and receiving an Echo Reply, for
> | diagnostic purposes.
> |
> | An ICMP Echo Request destined to an IP broadcast or IP
> | multicast address MAY be silently discarded.
>
> So, uhm, no. Hosts *are* definitely required to return something. It's
> required, you see the "MUST" in the first line of the quoted section?
But nothing requires the network to which they are connected to allow
them to receive the requests, or allow the responses to get out..
And the RFC still doesnt prevent an administrative decision to disable
the feature. A lot of the RFC's were implemented back before the net was
as hostile a place as it is now, so are no longer quite as well advised
as they were..
> But this is entirely irrelevant to Ralf's problem.
Indeed. AFAIK exim does not ping hosts..
It was probably a temporary DNS failure, which was resolved by the time
he checked manually..
>
> MBM
>
> --
> Matthew Byng-Maddick <mbm@???> http://colondot.net/
>
> --
>
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>
>
