Re: [squid-users] File corruption with reverse proxy

From: Marcus Kool <>
Date: Tue, 28 Aug 2012 13:51:26 -0300

On 08/28/2012 10:21 AM, Andy Osborne wrote:
> Hi All,
> I'm trying to debug a problem at the moment where a small
> proportion of people visiting our sites (Squid 3.1.20 as a reverse
> proxy with Apache origin servers) are seeing file corruption.
> So far all the confirmed cases are using Windows 7 with
> IE 9 or a recent Chrome. Unfortunately we can't reproduce
> the problem on any machine we have, which is making it
> difficult to debug.
> The corruption doesn't always occur but when it does it looks
> like a few contiguous bytes getting one or two bits flipped.

It is extremely unlikely that a few bits get flipped by
Squid, the netowrk layer or any other component except
non-ECC memory.
Does the server that runs Squid have ECC or non-ECC memory?


> I managed to get access to a PC belonging to a client to do
> some testing. This machine has the problem and runs Win 7
> Pro (64 bit). Unplugging it from the network and using
> it's ethernet cable to test using a variety of laptops (Mac,
> Win 7, Win XP) showed no problems. That would normally
> be enough to put the whole thing down to some weird
> Windows bug and give up.
> However, overriding DNS via the hosts file to point this
> problematic machine directly at an origin server made
> the problem disappear. I still think it's probably a Windows
> bug, but it seems that something about the reverse proxy
> (Squid or the machine running it) is triggering the bug.
> Test downloads from various locations hasn't found any
> difference between files downloaded directly or via the
> reverse proxy. Basically, all my testing shows no problems.
> Has anyone else seen a similar problem recently ?. One
> reason to support it being a Windows bug is that it only
> started occurring about 3 weeks ago and we haven't changed
> anything in our hosting set up in that time frame.
> It would also be a help if anyone can point me at some sites
> that are known to be using Squid as a reverse proxy. Seeing
> if they also exhibit the problem might help to narrow things
> down.
> Cheers,
> Andy
Received on Tue Aug 28 2012 - 16:51:32 MDT

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