Re: [squid-users] RE: Squid 3.0 as reverse proxy

From: Henrik Nordstrom <henrik_at_henriknordstrom.net>
Date: Tue, 24 Nov 2009 00:23:58 +0100

mån 2009-11-23 klockan 15:34 +0100 skrev Sébastien WENSKE:
> Sorry I've make a mistake, the url to get the original picture is http://gallery.wenske.fr/wallpapers/holland_dream_2560x1600.jpg.html?z&p=full-image
>
> This will force the download of the picture.

That's a very very cache-unfriendly object..

Some key elements from the response header:

Expires: Thu, 19 Nov 1981 08:52:00 GMT

Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0

Pragma: no-cache

Last-Modified: Mon, 23 Nov 2009 23:14:13 GMT

Vary: Accept-Encoding

And my comments:

Expires is set in the past, which forces caches to revalidate the object on each request.

Cache-Control no-store is a very aggressive nocache directive. Forbids
everyone involved from storing the response on any form of persistent
storage. I.e. not even browsers are allowed to cache the object in their
disk cache, and they must also remove it as soon as possible from the
memory cache. Really only intended for very sensitive responses where it
would be a major disaster if an unauthorized third party got hold of the
response by stealing the computer and inspecting the cached files and
similar scenarios.

Cache-Control no-cache & must-revalidate, also quite unfriendly and says
that the response MUST be validated with the origin before reuse.

Regards
Henrik
Received on Mon Nov 23 2009 - 23:24:11 MST

This archive was generated by hypermail 2.2.0 : Tue Nov 24 2009 - 12:00:04 MST