sshd service removed by Windows 10 update 1803

Cliff Geschke
Thu Jul 19 12:39:00 GMT 2018

As part of a Windows 10 update 1803 a few days ago, the cygwin sshd service was
removed, keeping my users from accessing my server.  I had been successfully
using sshd for several years and it has survived numerous windows updates.

Here is what I have done to fix it:

Disable the following services via W10 computer management.
  OpenSSH Authentication Agent
  SSH Server Broker
  SSH Server Proxy

I'm not sure all those need to be disabled.

Run a bash shell as administrator, and reinstall sshd using cygrunsrv

cygrunsrv --stop sshd
cygrunsrv --remove sshd
cygrunsrv --install sshd --path /usr/sbin/sshd.exe --user cyg_server
cygrunsrv --start sshd

You will get an error from the start command: 
  cygrunsrv: Error starting a service: QueryServiceStatus:  Win32 error 1062:
  The service has not been started.

The task manager shows sshd is indeed running, and remote ssh clients can log
in.  So I am ignoring the error.

cygrunsrv -Q sshd shows the service is stopped.  And W10 computer management
shows it is stopped.  If you try to start it again, it will fail because the
sshd task has a hold on the TCP ports.  If you want to stop/restart to edit
config files, you need to directly kill the sshd task.

After a system restart, W10 starts the correct sshd again.

Simply using "cygrunsrv --install sshd" without --path, installs the MS sshd.
Not what I want.

If you don't specify --user with the --install, W10 will use SYSTEM which does
not have the permissions (SeTcbPrivilege etc) to change to the client user.  So
you get seteuid Operation Not Permitted errors when a remote client tries and
fails to login.  I discovered this the hard way.

BTW, I didn't want to start over with ssh-host-config because I didn't want to
risk invalidating my encryption keys and confuse my remote clients.

Except for the weirdness where computer management and cygrunsrv -Q show the
service is stopped, everything seems to work okay and my users are happy again.

Cliff Geschke
Precise Automation

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