OpenSSH: SSHD daemon (as SYSTEM) is partially broken

Thu Feb 27 18:09:00 GMT 2020

It appears Cygwin SSHD's functionality is partially broke in the later
versions, where SSHD runs as SYSTEM (no longer cyg_server).

On reboot, any attempt to SSH into the server *before* any previous logon
attempt (RDP/locally/etc) is quickly denied:

   debug1: Offering public key: /home/<user>/.ssh/id_rsa
   debug3: send_pubkey_test
   debug2: we sent a publickey packet, wait for reply
   Connection closed by <server_addr>
Once an RDP/local login is attempted, regardless of success/failure,
subsequent ssh attempts will progress to the password prompt which
eventually gets us in.

The Event Viewer shows the attached error message, relating to a NULL SID
and 0xC00000BB status.

It was a rather vanilla 'ssh-host-config' run to get it installed: strict
modes = no, no special ssh_/sshd_config settings at this point.

Running latest cygwin packages on Windows Server 2016 Standard:
CYGWIN_NT-10.0 <server_name> 3.1.4(0.340/5/3) 2020-02-19 08:49 x86_64 Cygwin
openssh              8.2p1-1            OK

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