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From: Chris Stankevitz <chris@stankevitz.com>
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To: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net>
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Subject: Re: ssh over WAN: TCP window too small
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On 8/25/15 4:11 PM, Bjoern A. Zeeb wrote:
>
>> On 25 Aug 2015, at 22:47 , Chris Stankevitz <chris@stankevitz.com> wrote:
>>
>> Can anyone recommend some tools/tricks to figure out what in FreeBSD and/or
 >> base SSH is limiting the send/recv buffer and/or TCP window?
>
> if you have the memory, try these sysctls:
>
> kern.ipc.maxsockbuf=146800640
> net.inet.tcp.recvbuf_max=67108864
> net.inet.tcp.sendbuf_max=67108864

Bjoern,

Thank you for the reply.  Before your suggestion my sysctls are:

  kern.ipc.maxsockbuf=2097152
  net.inet.tcp.recvbuf_max=2097152
  net.inet.tcp.sendbuf_max=2097152

Each of these is much larger than the limit I am experiencing (~64,000). 
  So I [naively] expect changing these values will have no effect.  Let 
me try...

... okay... sure enough the sysctrl changes you suggest did not change 
the 64,000 bytes-in-flight limit I am experiencing.

Thanks for the idea (and keep 'em coming!),

Chris