TCP Window Scaling issue

Michael Brown michael at
Thu Jul 24 16:35:02 UTC 2014

On 14-07-24 12:25 PM, Tony Finch wrote:
> Zach Hill <zach.reborn at> wrote:
>> What's interesting is this is only affecting a single server and only
>> when traffic is going over the WAN circuit. Testing from Server A to any
>> server on it's network shows it is negotiating window scaling just fine.
> Check your firewall isn't buggering about with TCP options.
> Tony.
This, exactly. I diagnosed this issue a while back with our Checkpoint
firewall - it didn't understand TCP window scaling so it would blindly
zero out the field and cause nightmares.


Michael Brown            | The true sysadmin does not adjust his behaviour
Systems Administrator    | to fit the machine.  He adjusts the machine
michael at  | until it behaves properly.  With a hammer,
                         | if necessary.  - Brian

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