Re: [squid-users] Unable to access IIS site through squid3

From: Amos Jeffries <>
Date: Fri, 02 Dec 2011 01:13:37 +1300

On 1/12/2011 4:45 a.m., Fredrik Eriksson wrote:
> On 11/30/2011 02:06 AM, Amos Jeffries wrote:
>> Data packet from Squid->Server. 1085 bytes. Well under both 1160 and
>> 1460 sizes, even with TCP packet bits added.
>> However the packet checksum is incorrect.
>> This is a problem in the kernel code somewhere. Given that it works on
>> the same box with older Squid it is likely something to do with the
>> IPv4/IPpv6 v4-mapping features of the kernel. Squid-3.1 prefers to use
>> "v4-mapped" IPv6 sockets and let the kernel swap the TCP stacks around
>> depending on the IP address type connected to.
> I'm not entirely sure what you said here, but I tried to pursue the
> issue further based on this having to do something with the kernel and
> perhaps IPv6.

Ah sorry. In short I think its a kernel bug in the TCP / IP support.

> On the old squid2 server, running debian etch, we have linux
> 2.6.18-6-686. To make sure, I installed squid 2.7.STABLE9-2.1 on the
> squid3 server, changed the http_port, to be able to run both at the
> same time, and verified that we could indeed access from
> the same host running a 2.x version of squid.
> After that I have tried both changing linux from 2.6.32-5-amd64 (from
> debian stable) to 2.6.38-bpo.2-amd64 (from squeeze-backports) as well
> as completely disable IPv6 on the host. We don't use IPv6 and have no
> IPv6 connections to the outside world, but the interfaces did, of
> course, have link-local addresses, however, disabling IPv6 did not
> make any difference to the state of not being able to access the site.
> Is there any other information I could provide you with? To my
> knowlege, this is the only site we are having these problems with.

I hate to say this, but if all else fails you will probably need to
--disable-ipv6 in Squid to get back to the IPv4-ony behaviour Squid-2
had. That wont exactly solve the problem, but should avoid it.

Received on Thu Dec 01 2011 - 12:13:43 MST

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