TCP zero window probing

It seems that to probe a closed receive window,
linux TCP implementation sends an empty segment
with its sequence number set to SND.UNA-1.
I was wondering if this was compliant with RFC
793 which does not seem to describe precisely
what such a probe should contain.

Thanks,
Louis.

Louis Laborde <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...
> It seems that to probe a closed receive window,
> linux TCP implementation sends an empty segment
> with its sequence number set to SND.UNA-1.
> I was wondering if this was compliant with RFC
> 793 which does not seem to describe precisely
> what such a probe should contain.
>
> Thanks,
> Louis.

I'm just now probing the minutiae of the IP/TCP rfcs (on an "as
needed" basis), so this may miss the mark by a wide margin.

Not familiar with what value "SND.UNA-1" represents (ie., where the
var[?] SND-UNA comes from) -- be warned.

I did find this:
http://www.faqs.org/rfcs/rfc1122.html
specifically section:
4.2.2.17 Probing Zero Windows: RFC-793 Section 3.7, page 42
(it is referring to RFC-793 and is itself listed as "[STD 3]
Requirements for Internet Hosts.")

The above site offers full text searches of RFCs -- found above with:
receive window
which produced:
Results Summary for query "receive window":
262 matches in 63 files

Sorry, not possible to provide a direct link to results page and
"eyeballed" the rfc1122 hit -- it's the last one, #63. Provides
sentence context of hits in each document.

BTW, if you know of any other good rfc search repositories, I would be
interested to know. I also use
http://www.networksorcery.com/enp/default0601.htm .

hth,
prg
email above disabled