[ntp:questions] Re: server's address in ntp payload?

Danny Mayer mayer at ntp.isc.org
Sun Nov 27 01:57:14 UTC 2005


David Schwartz wrote:
> "Danny Mayer" <mayer at ntp.isc.org> wrote in message 
> news:43876FE3.1010309 at ntp.isc.org...
> 
>>As long as you don't receive packets on the wildcard addresses your
>>response will go out using the same address as the packet was received
>>on. It's the wildcard addresses that cause the problem and you cannot
>>know which address the kernel may choose.
> 
> 
>     Right. RFC1123 says:
> 
> 
>          *    "SHOULD"
> 
>               This word or the adjective "RECOMMENDED" means that there
>               may exist valid reasons in particular circumstances to
>               ignore this item, but the full implications should be
>               understood and the case carefully weighed before choosing
>               a different course.
> 
>     and
> 
>      When the local host is multihomed, a UDP-based request/response
>       application SHOULD send the response with an IP source address
>       that is the same as the specific destination address of the UDP
>       request datagram.
> 
>     What this means is that a UDP-based request/response application must 
> send responses with the source address that was the destination in the reply 
> unless the full implications of not doing so are understood and the case is 
> carefully weighed. Failure to do this is failure to comply with RFC1123. 
> RFC1123 states the host *requirements* for being part of the Intenet.


Then you don't understand the paragraph you just quoted. SHOULD is a
recommendation and not a requirement. You cannot violate a
recommendation. You used the word "must" which is not in the section you
quoted.

In any case we do do this.

Danny




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