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Date:      Fri, 4 Apr 2008 13:14:19 -0700 (PDT)
From:      s3raphi <seraphi.lord@gmail.com>
To:        freebsd-net@freebsd.org
Subject:   Re: TCP options order changed in FreeBSD 7, incompatible with some routers
Message-ID:  <16497816.post@talk.nabble.com>
In-Reply-To: <f383264b0803211553s6651fec4lb4b6f2a2f2e4af4a@mail.gmail.com>
References:  <f90b44e40803111756h517b373ala8afdff9395b7fac@mail.gmail.com> <47D860AC.6030707@freebsd.org> <f90b44e40803201909i2aab437bp58bc06755f60500f@mail.gmail.com> <f383264b0803211553s6651fec4lb4b6f2a2f2e4af4a@mail.gmail.com>

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I upgraded many web servers to FreeBSD 7.0-Release several weeks ago. These
servers serve hundreds of thousands of users. Since then, we have had many
users complain that they cannot connect to these servers any more. This was
a very tricky problem to diagnose, but using packet captures on both the
servers and the clients who have the problem I ended up with the same
results as the original poster. The user can ping the server with ICMP. The
user cannot complete a TCP connection.
Client sends SYN to server
Server responds SYN/ACK
Client packet capture does not show the SYN/ACK arrive.
Connection fails.

The windows client was running wireshark.

This problem is specific to windows, but also the network it is on or
devices it goes through. The same user experiencing the problem tried to
connect using a mac, and the problem does not manifest itself. Both the mac
and the windows pc were on the same network, behind the same SOHO router,
same ISP, and talking to the same FreeBSD7.0-RELEASE server. 

Baffled by what the problem could have been, I stood up one of the old
FreeBSD 6.1 servers which had not yet been replaced with FreeBSD7. The user
has no trouble at all accessing the FreeBSD 6.1 server.

More interesting info:
-This makes it look like windows:
Fails: WindowsXPpro PC -> SOHO -> ISP -> Internet -> MyDataCenter ->
FreeBSD7
Works: MacBook -> SOHO -> ISP -> Internet -> MyDataCenter -> FreeBSD7

-This makes it look like the network(router/firewall/etc..):
If the WindowsPC connects to our office VPN, the connection to the FreeBSD7
server will work without issue.

The problem is specific to some combination of Windows and networks or
network devices. I have seen users on many different ISPs, and with many
different flavors of routers/firewalls.

-The problem only effects a small percentage of our users. Most of our
Windows users have no issue.

This is a very serious problem for anyone using FreeBSD7 in production as an
internet facing server as a huge percentage of clients will be windows, and
a percentage of those users will no longer be able to use your web services. 

Can the patch be made available to freebsd-update?

-Seraphi


Matt Reimer wrote:
> 
> On Thu, Mar 20, 2008 at 7:09 PM, d.s. al coda <coda.trigger@gmail.com>
> wrote:
>> On 3/12/08, Andre Oppermann <andre@freebsd.org> wrote:
>>
>>  >
>>
>> > I'd be very interesting to know the exactly models and their firmware
>>  > version
>>  > of the affected routers.  If available locally I'd like to obtain a
>>  > similar
>>  > model myself for future regression tests.
>>
>>
>>  Here are the models we managed to hear about via email:
>>  D-Link WBR-1310
>>  Linksys WCG200 (with firewall enabled)
>>  Encore Broadband Router
>>  Linksys WAG354G
>>  Ambit U10C019
>>  Netgear CG814GCMR
> 
> I've seen this on a Netgear CG814WG.
> 
> Matt
> _______________________________________________
> freebsd-net@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
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> 
> 

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