openssh unix dev - Aug 2018 - sshd 7.8p1 close connection from VMware Fusion NAT Port Forwarding

After upgrading my VMware Fusion (10.1.3) Arch Guest to the latest with
OpenSSH upgraded from 7.7p1 to 7.8p1, found that ssh from macOS Sierra
(10.12.6) host to Arch guest via local NAT port forwarding failed, but via
Arch LAN IP worked, downgraded OpenSSH from 7.8p1 to 7.7p1 fixed the
problem.

Any idea about this bug?

VMware Fusion NAT Port Forwarding setup:
VMware Fusion ? NAT Port Forwarding 101 | www.weatherhead.net
http://www.weatherhead.net/2015/06/21/vmware-fusion-nat-port-forwarding-101/

Arch openssh PKGBUILD:
PKGBUILD\trunk - svntogit/packages.git - Git clone of the 'packages'
repository
https://git.archlinux.org/svntogit/packages.git/tree/trunk/PKGBUILD?h=packages/openssh

Here are ssh and sshd logs:
OpenSSH 7.8p1 close connection from VMware Fusion NAT Port Forwarding
https://gist.github.com/ZachCheung/9e48769067ac6681c419fb46f480fb90

On 2018-08-27, Zach Cheung <kuroro.zhang at gmail.com>
wrote:
> After upgrading my VMware Fusion (10.1.3) Arch Guest to the latest with
> OpenSSH upgraded from 7.7p1 to 7.8p1, found that ssh from macOS Sierra
> (10.12.6) host to Arch guest via local NAT port forwarding failed, but via
> Arch LAN IP worked, downgraded OpenSSH from 7.8p1 to 7.7p1 fixed the
> problem.
>
> Any idea about this bug?
I bet it is the QoS change. Try "IPQoS lowdelay,throughput".

On 2018-08-27, Stuart Henderson <stu at spacehopper.org>
wrote:
> On 2018-08-27, Zach Cheung <kuroro.zhang at gmail.com> wrote:
>> After upgrading my VMware Fusion (10.1.3) Arch Guest to the latest with
>> OpenSSH upgraded from 7.7p1 to 7.8p1, found that ssh from macOS Sierra
>> (10.12.6) host to Arch guest via local NAT port forwarding failed, but
via
>> Arch LAN IP worked, downgraded OpenSSH from 7.8p1 to 7.7p1 fixed the
>> problem.
>>
>> Any idea about this bug?
>
> I bet it is the QoS change. Try "IPQoS lowdelay,throughput".
Sorry, should be separated by whitespace: "IPQoS lowdelay throughput".
(This restores the pre-7.8 setting).

On Mon, 27 Aug 2018, Stuart Henderson wrote:
> On 2018-08-27, Zach Cheung <kuroro.zhang at gmail.com> wrote:
> > After upgrading my VMware Fusion (10.1.3) Arch Guest to the latest
with
> > OpenSSH upgraded from 7.7p1 to 7.8p1, found that ssh from macOS Sierra
> > (10.12.6) host to Arch guest via local NAT port forwarding failed, but
via
> > Arch LAN IP worked, downgraded OpenSSH from 7.8p1 to 7.7p1 fixed the
> > problem.
> >
> > Any idea about this bug?
> 
> I bet it is the QoS change. Try "IPQoS lowdelay,throughput".
Do you have any insight into what is breaking here? I don't believe
changing the default DSCP values should break connections...

-d