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Date:      Sat, 28 Oct 2023 11:42:11 +0000
From:      Roger Marsh <r.m@rmswch.plus.com>
To:        stable@freebsd.org
Subject:   Re: Version of OpenSSH in FreeBSD 14.0
Message-ID:  <20231028114211.7e0eceaa@opendev.home>
In-Reply-To: <5a16a0e2-34c2-4bcf-bfbe-aec980955fcf@twisted.org.uk>
References:  <20231028083010.0f880289@opendev.home> <5a16a0e2-34c2-4bcf-bfbe-aec980955fcf@twisted.org.uk>

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On Sat, 28 Oct 2023 10:45:36 +0100
Pete French <pete@twisted.org.uk> wrote:

> On 28/10/2023 09:30, Roger Marsh wrote:
> > Does 14.0 have OpenSSH 9.3 or OpenSSH 9.4?
> > 
> > This thread:
> > 
> > Delay in starting programs on FreeBSD via ssh after upgrade OpenBSD from 7.3 to 7.4 >
> > on openssh-unix-dev@mindrot.org  
> 
> 
> This one ?
> 
> https://lists.mindrot.org/pipermail/openssh-unix-dev/2023-October/041033.html
>

Yes.
 
> Just looking at that thread and not being able to quite work out what
> the solution was there (it refers to another thread I cant find). But
> it seems to be ObscureKeystrokeTiming, yes ?
> 

Thread you cannot find is:

https://marc.info/?l=openbsd-misc&m=169824753806131&w=2

> There are no references to that in the config on FreeBSD 14, so I assume
> it stays on, and at the default. Did this turn out to be the cause of
> the issue, and did disabling it fix the problem ?
>

On OpenBSD the default for ObscureKeystrokeTiming is on, value 'yes', and it can be turned off, value 'no'.  Intervals can be specified too: quoting OpenBSD 7.4 'man ssh_config' for ObscureKeystrokeTiming "The default is to obscure keystrokes using a 20ms packet interval.".

Disabling fixed the problem.
 
> I have to admit I hadn't tried ssh'ing *out* of my test 14 box
> until today, but a quick try doesnt show any delays to anything.
> However I don't have anything running OpenBSD.
> 

One of the posts in the thread on openbsd-misc has a table on this sort of ssh'ing combination (for OpenBSD only).

One of the replies on the openbsd-misc thread pointed out why one of the logins took a long time!  (It does not get used during upgrades which is why I did not notice the problem till 'too late'.)

> -pete.
> 
> PS: I did see an upgraded ssh cause delays in login a while ago. But
> that turned out to be dropping support for old key exchange algorithms.
> If the box you are sshing into is somewhat underpowered then it can
> take longer to do the key echange, as the newer algorithms are far
> slower. In my case the delay was 30 seconds to login.
> 

Delay seems to be about five seconds, measured by mutterring "One thousand and one, ..., ... and five" while waiting.

The ssh_config entry for ObscureKeystrokeTiming talks about fake keystroke packets after typing ceases.  I had not considered the possibility of key exchange problems.

> 

Apologies for the reference to OpenSSH 9.4.

On OpenBSD 7.4 

both 'ssh -V' and 'sshd -V' give 'OpenSSH_9.5, LibreSSL 3.8.2'.

Looks like the problem will go away after I upgrade to FreeBSD 14.0.

Roger



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