squid not always using cache

i'm running squid on a transparent proxy server. when i do windows
updates sometimes it uses the cache and sometimes it doesn't. I'm
running slackware 10.2 and the newest version of squid. Is there any
way i can fix this?

thanx in advance
constant meiring

Whether use or not cache depends on Expires: field in web server
response which might give for example
"Expires: Thu, 19 Nov 1981 08:52:00 GMT"
which means that page (or file) is not intended for caching,
or for example, server says that file expire after 4 days after
downloading

but it's windows update files. Should they expire?

"Slacknix" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) ups.com...

> but it's windows update files. Should they expire?

It would be interesting to see what headers you're getting on those
files. One would think they'd be set to expire fairly far in the future.
Make sure the clock is correct on your caching proxy!

DS

Slacknix wrote:
> but it's windows update files. Should they expire?

First, please quote what you are answering. This is a newsgroup, not a
web forum!

Second, windows update are using many servers, you may be connecting
to two different IPs.

Trygve Selmer wrote:

>First, please quote what you are answering. This is a newsgroup, not a
>web forum!

>Second, windows update are using many servers, you may be connecting
>to two different IPs.

The MD5 on the file should be the same as it's the same file, made on
the same date, same time, same everything.

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Slacknix wrote:
> i'm running squid on a transparent proxy server. when i do windows
> updates sometimes it uses the cache and sometimes it doesn't. I'm
> running slackware 10.2 and the newest version of squid. Is there any
> way i can fix this?


!!! WORD OF WARNING !!!

Use at your own risk.

Do not use refresh_pattern with other url:s than those mentioned below
without thorough testing. Who knows what can happen and you may find
yourself in serious trouble if people using your cache gets pages that
are frozen in time or otherwise damaged.

!!! YOU HAVE BEEN WARNED !!!








For quite some time Microsoft sends a 'do not cache this'-commmand with
the updates telling any caching servers to fetch directly from the
update servers.




The following three lines fix that. Put them in squid.conf and tell
squid to reconfigure or restart. Then start updating. Sometimes it can
take a couple of updates for it to settle.

- ----- squid.conf -----
refresh_pattern download.windowsupdate.com/ 0 80% 43200 reload-into-ims
refresh_pattern update.microsoft.com/ 0 80% 43200 reload-into-ims
range_offset_limit -1
- ----- squid.conf -----

(If these patterns do not work you have to look through access.log to
find what goes instead. They tend to change from time to time.)




The two lines beginning with 'refresh_pattern' tells squid to force
caching of 'no-cache'-objects.

The 'range_offset_limit' tells squid to cache whole objects even when
clients use range-requests to fetch only parts of huge files. Microsoft
started using that with some service packs and those files can be
several hundred megabytes in size.


Hope that helps.


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