[SQU] Squid running on Red Hat 6.2 as transparent proxy locks up MSIE 5

From: Stuart Parker <stuart@dont-contact.us>
Date: Mon, 5 Mar 2001 16:50:11 +1100

Hi there,

We experienced a problem about 4 months ago whereby machines on 2
seperate networks had a problem connecting to one of our web sites.
The client machine if it was running Windows 95/98/NT and connecting
with Internet Explorer would lock up. The cpu would be using 100% of
the CPU and would not release it until IE was quit. In both cases it
turned out that both sites had a transparent proxy enabled.
Fortunately, we were able to communicate this to the network
administrators of both sites and upgrading/flushing the cache
appeared to fix the problem in both cases. However, the problem has
returned on another network and we expect that it will keep occuring,
so we would like to resolve the issue. The versions of Squid
previously affected were Squid 2.2Stable3 and 2.4Devel1. The current
network affected is transparently proxied by a machine running a Dell
PowerApp.cache which AFAIK runs some version of squid on RH6.2.

What I'm considering
1. In MSIE on the client, turning off "Use HTTP/1.1" in the Internet
Options stops the lockup from occuring. Obviously we can't tell all
of our visitors to do this when they visit our site though.

2. Upgrading or flushing Squid also fixes the problem (could squid
somehow simply get corrupted? If so any idea how to prevent it?).

3. Red Hat Linux 6.2 appears to be a consistent factor here. In
section 14.5 of the FAQ I can't find anything specific to RH6.2 but I
can't shake the feeling there is something here.

4. I have read about half-closed connections and how it is poor form,
but I don't know which clients/servers this affects.

5. I read in the archives that squid does not support pipelining and
does not act as a HTTP 1.1 proxy. I understand that this means that
squid will chain a couple of requests together using keepalive but
that's it. Is there any more documentation/notes on this and any
potential issues it could cause?

6. I've tried to downgrade responses via the following line in our
apache configuration file in the hope that this would force all
connections into a 1.0 mode, but it didn't work.
BrowserMatch "MSIE 5" nokeepalive downgrade-1.0 force-response-1.0

7. If I send a HTTP/1.1 request from a machine which is inside the
transparent proxys realm, it is downgraded to a 1.0 request silently
(at least it appears in the apache logs as a 1.0 request). This leads
me to think that some combination of squid running on RH6.2 as a
transparent proxy is somehow misrepresenting a HTTP 1.1 request from
MSIE and possibly causing some data to be malformed upon return which
throws MSIE into some sort of infinate loop.

If anyone can help with some pointers or advice it would be greatly

Thanks in advance,

Stuart Parker
Web Objectives
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Received on Sun Mar 04 2001 - 22:54:58 MST

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