Very Computer

1. IE5.5 caching "no-cache" files when HTTP/1.0 proxy is used

I've come across an issue with the caching in Internet Explorer 5.5
and higher (I don't know whether it happens in earlier versions),
which only occurs when the browser is set up to use a cache. I've got
a page which should never be cached, even with the use of the back and
forward buttons, so I include the following headers in the response:

Cache-Control: no-store, no-cache, must-revalidate, post-check=0,
pre-check=0, max-age=0, private, no-transform, proxy-revalidate
Pragma: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Age: 0

(Obviously, the cache-control header is all on one line. I've also
tried many other combinations of cache-control parameters; the headers
above are the most stringent ones that I've tried.)

When IE5.5 is not set up to use a proxy server, it correctly
re-requests the page from the server when the user presses the back
button to return to it.

However, when IE5.5 is set up to use a proxy server, it does not
re-request the page when the user presses the back button to return to
it. It uses a locally cached copy, even though the cache-control and
pragma headers indicate that the page should not be cached. It also
maintains the state of the form elements on the page.

I've confirmed (using network monitoring) that IE5.5 is still
receiving the headers as given above (and in further detail below),
and is definitely not re-requesting the page when using a proxy
server. I also note that the proxy server is returning a HTTP/1.0
response; IE5.5 still shouldn't cache the page, because the Pragma
header is there. Is this a known caching issue with IE5+/IE5.5? More
importantly, is there a known fix or work-around?

(below I've given the complete headers returned for both the direct
connection to the server, and the response from the proxy server. The
Age header was only sent to make the direct and cached responses as
similar as possible. The behaviour is the same regardless of whether
or not IE5.5 is configured to use HTTP/1.1 through proxies; the proxy
in use only supports HTTP/1.0.)

Any help would be appreciated.

Grant Husbands.

Headers from the direct response:
HTTP/1.1 200 OK
Date: Thu, 29 Nov 2001 14:06:28 GMT
Server: Apache/1.3.9 (Unix) Debian/GNU
Age: 0
Cache-Control: no-store, no-cache, must-revalidate, post-check=0,
pre-check=0, max-age=0, private, no-transform, proxy-revalidate
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Pragma: no-cache
Keep-Alive: timeout=15, max=98
Connection: Keep-Alive
Transfer-Encoding: chunked
Content-Type: text/html

Headers from the proxied response:
HTTP/1.0 200 OK
Date: Thu, 29 Nov 2001 13:58:01 GMT
Server: Apache/1.3.9 (Unix) Debian/GNU
Cache-Control: no-store, no-cache, must-revalidate, post-check=0,
pre-check=0, max-age=0, private, no-transform, proxy-revalidate
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Pragma: no-cache
Content-Type: text/html
Age: 0
X-Cache: MISS from gold
X-Cache-Lookup: MISS from gold:8080
Proxy-Connection: close

2. Keeping shortcut icons persistant

3. Can't visit certain Web Sites "No-Cache = Set Cookies"

4. Turn Off Floating Dialog over JPEGS?

5. Dual Boot XP-98SE Drive Lettering question

6. cache News server (news cache-"proxy") on demand... will DNews suit?

7. LAN Testers

8. Question about cache-control = no-cache http header parameter

9. HTTP/1.0 404 Error connecting to site Pragma: no-cache Content-Type: text/html S

10. Pan Am Song ( was missing on my previous post" On Pan Am wings" )

11. Can Internet Explorer 5.x send the "pragma: no-cache" request header?

12. proxy server sends Pragma - no-cache HTTP header