OpenSSH on Windows with key authentication

KPacheco

12/6/23, 8:33 PM

I am attempting to get key based auth working on OpenSSH on Windows Server 2019. Currently we installed Open SSH according to the Microsoft docs and can login using our AD logins using password auth but when following instructions for key based authentication the following errors start to pop up.

On the client side we get this:

client_loop: send disconnect: Connection reset

Google results seem to think this is a timeout of some sort but its happening instantaneously before we get a prompt.

On the host side we are seeing the following in the event viewer:

sshd: fatal: fork of unprivileged child failed

Google results for this suggest processes are being used up but that seems unlikely in our situation.

Our setup is standard following the documentation found here, the only change made to the sshd config is to enable key authentication, everything else is default post installation. Happy so supply any additional information, unsure what else might be relevant.

EDIT: Did a little more digging and with a verbose output it looks like the public key is accepted but it closes the connection immedeiatly after:

Authenticated to <ip> ([<ip>]:22).
debug1: channel 0: new [client-session]
debug1: Requesting [email protected]
debug1: Entering interactive session.
debug1: pledge: network
debug1: ENABLE_VIRTUAL_TERMINAL_INPUT is supported. Reading the VTSequence from console
debug1: ENABLE_VIRTUAL_TERMINAL_PROCESSING is supported. Console supports the ansi parsing
client_loop: send disconnect: Connection reset

Its now attempting key based auth even when I dont supply a key with -i which is odd.

507

1 + 0

ssh

windows-server-2019

Score:0

Server

Manu

12/7/23, 8:49 AM

I don't know if this sill applies but back when we set up OpenSSH for Windows, Microsofts documentation and out of the box features were not working.

We used these sources and instructions to set it up properly:

regarding configuration our sshd_config contains among other things:

AuthorizedKeysFile  .ssh/authorized_keys
Subsystem   sftp    sftp-server.exe
Match Group administrators
       AuthorizedKeysFile __PROGRAMDATA__/ssh/administrators_authorized_keys

sftp settings because we use it mainly to move files (please don't ask why).

+ 1

KPacheco

12/21/23, 2:55 PM

Sorry for the delay in reply, All of that seems to be the default with the exception of the administrator keys. Unfortunately uncommenting the admin keys caused every attempt to login to break regardless of public key use.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: OpenSSH on Windows with key authentication

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.