[nSLUG] HTTP problem (or maybe IP/TCP?)

Mike Spencer mspencer at tallships.ca
Sat Mar 1 03:07:29 AST 2008

Is there any NSLUGger out there with some experience grovelling over
packet dumps who would regard doing same with a couple of (relatively)
short ones as recreational or otherwise agreeable? Not really a Linux
problem per se.

A problem arose sometime last fall such that one particular web site
would serve images to me under certain circumstances but not under others.
This would be unimportant except that it's the site where my own web
page resides and it will be an inconvenience as I'm about to do some
re-arrangement and updating.

I'm guessing that it is some change at the server because:

   + In the past there was no problem.
   + My browser hasn't changed.
   + The pages haven't changed.
   + My hardware and OS haven't changed.
   + The problem only occurs with images within pages on that one host.
     (Or, if it occurs elsewhere, it's so rare that I've never

The admin on the server doesn't know of any changes that could have
caused this.  I understand the elementary parts of RFCs 791 & 2616 but
not well enough to get very far with a subtle problem.  If I could
pinpoint the problem, I could tell the server admin what to fix.

It may be something that would be obvious/simple to an HTTP wizard.

The whole explanation is a bit tedious and the ethereal-interpreted
packet dumps/analyses of good and failed fetches run to 70K or 80K
(raw dumps 5K-6K) so I won't just post it all here.

But if you'd be entertained by looking at the details or otherwise
willing to do so, I'd be glad to hear from you by email, off-list.

- Mike


Michael Spencer                  Nova Scotia, Canada       .~. 
                                 (902) 543-8375            /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^

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