sshd: fatal: seteuid XXX : No such device or address

[<renaud dot rolles at giraudbtp dot com>]

Hello the list, 

Thanks for all the work and effort put into this.
Since two days i cannot login anymore (password less) with ssh into my
server

Server is : 
Microsoft Windows Server 2012 R2 Essentials / 6.3.9600 N/A version 9600

Cygwin was not up to date, but I have since updated it
CYGWIN_NT-6.3 [MACHINE NAME] 3.0.3(0.338/5/3) 2019-03-09 19:12 x86_64 Cygwin

I can login via password, it work and lets me in.
But if i tried with my keys, I get in the event viewer :
sshd: PID 3777: fatal: seteuid 1049076: No such device or address

I tried googling around, reinstalled multiple times sshd, the user and the
service with no luck so far.
I was working for several years now.

For now I have no clue, so i'm asking what did I do wrong ?

Renaud ROLLES 


Below the output of the ssh-host-config, with start and try
administrator@[MACHINE NAME] ~
$ ssh-host-config

*** Info: Generating missing SSH host keys
*** Query: Overwrite existing /etc/ssh_config file? (yes/no) yes
*** Info: Creating default /etc/ssh_config file
*** Query: Overwrite existing /etc/sshd_config file? (yes/no) yes
*** Info: Creating default /etc/sshd_config file

*** Info: StrictModes is set to 'yes' by default.
*** Info: This is the recommended setting, but it requires that the POSIX
*** Info: permissions of the user's home directory, the user's .ssh
*** Info: directory, and the user's ssh key files are tight so that
*** Info: only the user has write permissions.
*** Info: On the other hand, StrictModes don't work well with default
*** Info: Windows permissions of a home directory mounted with the
*** Info: 'noacl' option, and they don't work at all if the home
*** Info: directory is on a FAT or FAT32 partition.
*** Query: Should StrictModes be used? (yes/no) yes
*** Info: Updating /etc/sshd_config file

*** Query: Do you want to install sshd as a service?
*** Query: (Say "no" if it is already installed as a service) (yes/no) yes
*** Query: Enter the value of CYGWIN for the daemon: [] ntsec
*** Info: On Windows Server 2003, Windows Vista, and above, the
*** Info: SYSTEM account cannot setuid to other users -- a capability
*** Info: sshd requires.  You need to have or to create a privileged
*** Info: account.  This script will help you do so.

*** Info: It's not possible to use the LocalSystem account for services
*** Info: that can change the user id without an explicit password
*** Info: (such as passwordless logins [e.g. public key authentication]
*** Info: via sshd) when having to create the user token from scratch.
*** Info: For more information on this requirement, see
*** Info: https://cygwin.com/cygwin-ug-net/ntsec.html#ntsec-nopasswd1

*** Info: If you want to enable that functionality, it's required to create
*** Info: a new account with special privileges (unless such an account
*** Info: already exists). This account is then used to run these special
*** Info: servers.

*** Info: Note that creating a new user requires that the current account
*** Info: have Administrator privileges itself.

*** Info: No privileged account could be found.

*** Info: This script plans to use 'cyg_server'.
*** Info: 'cyg_server' will only be used by registered services.
*** Query: Do you want to use a different name? (yes/no) no
*** Query: Create new privileged user account '[MACHINE NAME]\cyg_server'
(Cygwin name: '[MACHINE NAME]+cyg_server')? (yes/no) yes
*** Info: Please enter a password for new user [MACHINE NAME]+cyg_server.
Please be sure
*** Info: that this password matches the password rules given on your
system.
*** Info: Entering no password will exit the configuration.
*** Query: Please enter the password:
*** Query: Reenter:

*** Info: User '[MACHINE NAME]+cyg_server' has been created with password
'UberSuperPassword1324'.
*** Info: If you change the password, please remember also to change the
*** Info: password for the installed services which use (or will soon use)
*** Info: the '[MACHINE NAME]+cyg_server' account.


*** Info: The sshd service has been installed under the '[MACHINE
NAME]+cyg_server'
*** Info: account.  To start the service now, call `net start sshd' or
*** Info: `cygrunsrv -S sshd'.  Otherwise, it will start automatically
*** Info: after the next reboot.

*** Info: Host configuration finished. Have fun!

administrator@[MACHINE NAME] ~
$ net start sshd
Le service CYGWIN sshd d-marre.
Le service CYGWIN sshd a d-marr-.


administrator@[MACHINE NAME] ~
$ ssh administrator@[MACHINE NAME]
Connection closed by fe80::8c27:9bb9:70e3:1a0c%12 port 22


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