openssh unix dev - Jan 2016 - SSH on high latency links. Re: [Patch] TCP MD5SIG for OpenSSH

On 15 January 2016 at 17:26, Roland Mainz <roland.mainz at nrubsig.org>
wrote:
>>> Don't these extra roundtrips further increase the latency of
ssh
>>> connection setup (e.g. imagine a
high-bandwidth&&high-latency satelite
>>> link) ? ssh is already a *PAIN* in that area, killing it's
usefullness
>>> for applications like "Distributed make" because the time
to setup the
>>> connection can be much longer than the command executed on the
remote
>>> side.
>> They would, but only when this non-default option was enabled.
> OK... are there any good ideas how to mitigate the latency effect ([1]) ?
You could try mosh (https://mosh.mit.edu/).

Thomas ? Habets wrote:
> On 15 January 2016 at 17:26, Roland Mainz <roland.mainz at
nrubsig.org> wrote:
>>>> Don't these extra roundtrips further increase the latency
of ssh
>>>> connection setup (e.g. imagine a
high-bandwidth&&high-latency satelite
>>>> link) ? ssh is already a *PAIN* in that area, killing it's
usefullness
>>>> for applications like "Distributed make" because the
time to setup the
>>>> connection can be much longer than the command executed on the
remote
>>>> side.
>>> They would, but only when this non-default option was enabled.
>> OK... are there any good ideas how to mitigate the latency effect ([1])
?
>
> You could try mosh (https://mosh.mit.edu/).
LINEMODE works too. https://github.com/hyc/OpenSSH-LINEMODE

-- 
   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/

On Fri, Jan 15, 2016 at 11:35 PM, Howard Chu <hyc at symas.com>
wrote:
> Thomas ? Habets wrote:
>> On 15 January 2016 at 17:26, Roland Mainz <roland.mainz at
nrubsig.org>
>> wrote:
>>>>>
>>>>> Don't these extra roundtrips further increase the
latency of ssh
>>>>> connection setup (e.g. imagine a
high-bandwidth&&high-latency satelite
>>>>> link) ? ssh is already a *PAIN* in that area, killing
it's usefullness
>>>>> for applications like "Distributed make" because
the time to setup the
>>>>> connection can be much longer than the command executed on
the remote
>>>>> side.
>>>>
>>>> They would, but only when this non-default option was enabled.
>>>
>>> OK... are there any good ideas how to mitigate the latency effect
([1]) ?
>>
>> You could try mosh (https://mosh.mit.edu/).
>
> LINEMODE works too. https://github.com/hyc/OpenSSH-LINEMODE
Isn't that an improvement only for interactive mode ? My point was
that something like $ ssh "$LOGNAME at desthost" '/bin/true' #
is
horrible slow compared to (Kerberised) rsh, and gets even worse on
high-latency links (problem is that the large number of roundtrips by
the ssh protocol makes the whole thing latency-sensitive to a high
degree).

----

Bye,
Roland

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