Re: Minor change to "Chapter 8. Remote OS Detection"

[Kris Katterjohn <katterjohn () gmail com>]

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On 05/07/2011 05:13 AM, Luis MartinGarcia. wrote:
> Hi,
>
> Current version of "Chapter 8. Remote OS Detection" says:
>
> "That length varies by implementation because they are allowed to choose
> how much data from the original probe to include, as long as they meet
> the minimum RFC 792 requirement. That requirement is to include the
> original IP header and at least eight bytes of data."
>
> I've been reading RFC 792, and the sentence above is not correct.
> Nowhere in the RFC it says that they are allowed to choose how much data
> from the original probe to include. I know implementations do what they
> want, but in theory, they should only include the original IP header
> plus the next 64 bits of data. This is why I suggest re-writing the
> sentence to something like the following:
>
> "That length varies because, although RFC 792 requires the inclusion of
> the original IP header plus the next 8 octets of data, some
> implementations include the whole datagram or more than 8 bytes of its
> payload."
>
> I attach a patch for this, although some native English speaker may want
> to do a bit of rewording.

Section 3.2.2 of RFC 1122 (Requirements for Internet Hosts):

"Every ICMP error message includes the Internet header and at
least the first 8 data octets of the datagram that triggered
the error; more than 8 octets MAY be sent; this header and data
MUST be unchanged from the received datagram."

This RFC updates and corrects some details in previous RFCs like 792 and 793,
and is the one implementations would follow for things like this, so just
changing the RFC number in Ch8 would be more accurate.

> Regards,
>
> Luis MartinGarcia.

Cheers,
Kris Katterjohn
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