RSA-Cert based Auth Not working in Windows

[txnovoid]

Troubleshooting steps
https://github.com/PowerShell/Win32-OpenSSH/wiki/Troubleshooting-Steps

Terminal issue? please go through wiki
https://github.com/PowerShell/Win32-OpenSSH/wiki/TTY-PTY-support-in-Windows-OpenSSH

Please answer the following

"OpenSSH for Windows" version
PS C:\ProgramData\ssh> ((Get-Item (Get-Command sshd).Source).VersionInfo.FileVersion)
7.7.2.1
Server OperatingSystem
((Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows nt\CurrentVersion\" -Name ProductName).ProductName)
PS C:\ProgramData\ssh> ((Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows nt\CurrentVersion" -Name ProductName).ProductName)
Windows Server 2019 Datacenter

Client OperatingSystem
CentOS8

What is failing

I have been working with the RSA-CERT authentication mechanisms in conjunction with Hashicorp's documentation. I have this working (mostly fine in CentOS8 as a Target. Configuring the same thing in Windows is not happening.

Life looks good up through here:
debug2: parse_server_config: config reprocess config len 365
debug3: checking match for 'Group administrators' user lab\MYUSER host 192.168.0.211 addr 192.168.0.211 laddr 192.168.0.130 lport 22
debug3: lookup_principal_name: Successfully discovered explicit principal name: 'lab\MYUSER'=>'MYUSER@mydomain.net'
debug3: LsaLogonUser Succeeded (Impersonation: 0)
debug1: user \001 matched group list administrators at line 85
debug3: match found
debug3: reprocess config:86 setting AuthorizedKeysFile PROGRAMDATA/ssh/administrators_authorized_keys
debug3: reprocess config:88 setting TrustedUserCAkeys PROGRAMDATA/ssh/trusted-user-ca-keys.pem

But then I get this error message:
userauth_pubkey: unsupported public key algorithm: rsa-sha2-256-cert-v01@openssh.com [preauth]

Which seems odd, because the documentation suggests that this is supported by default.

On the user end:

[USER@c8s1 ~]$ ssh -i signed-cert-win.pub -i ~/.ssh/id_rsa USER@192.168.0.130
USER@192.168.0.130: Permission denied (publickey,keyboard-interactive).

Now, this appears to be an AuthZ error (permission denied). Full debug log below

Expected output
Certificate Based Authentication works?

Actual output
C:\PSTools>psexec -s sshd.exe -ddd

PsExec v2.2 - Execute processes remotely
Copyright (C) 2001-2016 Mark Russinovich
Sysinternals - www.sysinternals.com

debug2: load_server_config: filename PROGRAMDATA\ssh/sshd_config
debug2: load_server_config: done config len = 365
debug2: parse_server_config: config PROGRAMDATA\ssh/sshd_config len 365
debug3: PROGRAMDATA\ssh/sshd_config:35 setting PubkeyAuthentication yes
debug3: PROGRAMDATA\ssh/sshd_config:39 setting AuthorizedKeysFile .ssh/authorized_keys
debug3: PROGRAMDATA\ssh/sshd_config:52 setting PasswordAuthentication no
debug3: PROGRAMDATA\ssh/sshd_config:77 setting Subsystem sftp sftp-server.exe
debug3: checking syntax for 'Match Group administrators'
debug1: sshd version OpenSSH_for_Windows_7.7, LibreSSL 2.6.5
debug1: private host key #0: ssh-rsa SHA256:EAhuImKrQbUk+v42huzU12vyD0iW/mYbNhetRnqD/Sw
debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:vkj2u3PENt3BxoG7Cm3Hrx0jliDdnZ5jp0L7WQkgfac
debug1: private host key #2: ssh-ed25519 SHA256:IsQ7vTGcMbtao4244AVeQEZ34D1pvvvH0kEonWdF1Fk
debug1: rexec_argv[0]='sshd.exe'
debug1: rexec_argv[1]='-ddd'
debug2: fd 3 setting O_NONBLOCK
debug3: sock_set_v6only: set socket 3 IPV6_V6ONLY
debug1: Bind to port 22 on ::.
Server listening on :: port 22.
debug2: fd 4 setting O_NONBLOCK
debug1: Bind to port 22 on 0.0.0.0.
Server listening on 0.0.0.0 port 22.
debug3: fd 5 is not O_NONBLOCK
debug1: Server will not fork when running in debugging mode.
debug3: send_rexec_state: entering fd = 8 config len 365
debug3: ssh_msg_send: type 0
debug3: send_rexec_state: done
Connection from 192.168.0.211 port 34466 on 192.168.0.130 port 22
debug1: Client protocol version 2.0; client software version OpenSSH_8.0
debug1: match: OpenSSH_8.0 pat OpenSSH* compat 0x04000000
debug1: Local version string SSH-2.0-OpenSSH_for_Windows_7.7
debug2: fd 5 setting O_NONBLOCK
debug3: spawning "C:\Windows\System32\OpenSSH\sshd.exe" "-ddd" "-y"
debug2: Network child is on pid 7928
debug3: send_rexec_state: entering fd = 4 config len 365
debug3: ssh_msg_send: type 0
debug3: recv_rexec_state: entering fd = 3
debug3: send_rexec_state: done
debug3: ssh_msg_recv entering
debug3: ssh_msg_send: type 0
debug3: recv_rexec_state: done
debug2: parse_server_config: config PROGRAMDATA\ssh/sshd_config len 365
debug3: ssh_msg_send: type 0
debug3: PROGRAMDATA\ssh/sshd_config:35 setting PubkeyAuthentication yes
debug3: preauth child monitor started
debug3: PROGRAMDATA\ssh/sshd_config:39 setting AuthorizedKeysFile .ssh/authorized_keys
debug3: PROGRAMDATA\ssh/sshd_config:52 setting PasswordAuthentication no
debug3: PROGRAMDATA\ssh/sshd_config:77 setting Subsystem sftp sftp-server.exe
debug3: checking syntax for 'Match Group administrators'
debug1: sshd version OpenSSH_for_Windows_7.7, LibreSSL 2.6.5
debug3: ssh_msg_recv entering
debug3: ssh_msg_recv entering
debug2: fd 5 setting O_NONBLOCK
debug1: list_hostkey_types: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
debug3: send packet: type 20 [preauth]
debug1: SSH2_MSG_KEXINIT sent [preauth]
debug3: receive packet: type 20 [preauth]
debug1: SSH2_MSG_KEXINIT received [preauth]
debug2: local server KEXINIT proposal [preauth]
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1 [preauth]
debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com [preauth]
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com [preauth]
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 [preauth]
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 [preauth]
debug2: compression ctos: none [preauth]
debug2: compression stoc: none [preauth]
debug2: languages ctos: [preauth]
debug2: languages stoc: [preauth]
debug2: first_kex_follows 0 [preauth]
debug2: reserved 0 [preauth]
debug2: peer client KEXINIT proposal [preauth]
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,ext-info-c [preauth]
debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa [preauth]
debug2: ciphers ctos: aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes256-ctr,aes256-cbc,aes128-gcm@openssh.com,aes128-ctr,aes128-cbc [preauth]
debug2: ciphers stoc: aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes256-ctr,aes256-cbc,aes128-gcm@openssh.com,aes128-ctr,aes128-cbc [preauth]
debug2: MACs ctos: hmac-sha2-256-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha1,umac-128@openssh.com,hmac-sha2-512 [preauth]
debug2: MACs stoc: hmac-sha2-256-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha1,umac-128@openssh.com,hmac-sha2-512 [preauth]
debug2: compression ctos: none,zlib@openssh.com,zlib [preauth]
debug2: compression stoc: none,zlib@openssh.com,zlib [preauth]
debug2: languages ctos: [preauth]
debug2: languages stoc: [preauth]
debug2: first_kex_follows 0 [preauth]
debug2: reserved 0 [preauth]
debug1: kex: algorithm: curve25519-sha256 [preauth]
debug1: kex: host key algorithm: ecdsa-sha2-nistp256 [preauth]
debug1: kex: client->server cipher: aes256-gcm@openssh.com MAC: compression: none [preauth]
debug1: kex: server->client cipher: aes256-gcm@openssh.com MAC: compression: none [preauth]
debug1: expecting SSH2_MSG_KEX_ECDH_INIT [preauth]
debug3: receive packet: type 30 [preauth]
debug3: mm_key_sign entering [preauth]
debug3: mm_request_send entering: type 6 [preauth]
debug3: mm_key_sign: waiting for MONITOR_ANS_SIGN [preauth]
debug3: mm_request_receive_expect entering: type 7 [preauth]
debug3: mm_request_receive entering [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 6
debug3: mm_answer_sign
debug3: mm_answer_sign: hostkey proof signature 0000016ED1C6AA10(100)
debug3: mm_request_send entering: type 7
debug2: monitor_read: 6 used once, disabling now
debug3: send packet: type 31 [preauth]
debug3: send packet: type 21 [preauth]
debug2: set_newkeys: mode 1 [preauth]
debug1: rekey after 4294967296 blocks [preauth]
debug1: SSH2_MSG_NEWKEYS sent [preauth]
debug1: expecting SSH2_MSG_NEWKEYS [preauth]
debug3: send packet: type 7 [preauth]
debug3: receive packet: type 21 [preauth]
debug1: SSH2_MSG_NEWKEYS received [preauth]
debug2: set_newkeys: mode 0 [preauth]
debug1: rekey after 4294967296 blocks [preauth]
debug1: KEX done [preauth]
debug3: receive packet: type 5 [preauth]
debug3: send packet: type 6 [preauth]
debug3: receive packet: type 50 [preauth]
debug1: userauth-request for user MYUSER service ssh-connection method none [preauth]
debug1: attempt 0 failures 0 [preauth]
debug3: mm_getpwnamallow entering [preauth]
debug3: mm_request_send entering: type 8 [preauth]
debug3: mm_getpwnamallow: waiting for MONITOR_ANS_PWNAM [preauth]
debug3: mm_request_receive_expect entering: type 9 [preauth]
debug3: mm_request_receive entering [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 8
debug3: mm_answer_pwnamallow
debug2: parse_server_config: config reprocess config len 365
debug3: checking match for 'Group administrators' user lab\MYUSER host 192.168.0.211 addr 192.168.0.211 laddr 192.168.0.130 lport 22
debug3: lookup_principal_name: Successfully discovered explicit principal name: 'lab\MYUSER'=>'MYUSER@mydomain.net'
debug3: LsaLogonUser Succeeded (Impersonation: 0)
debug1: user \001 matched group list administrators at line 85
debug3: match found
debug3: reprocess config:86 setting AuthorizedKeysFile PROGRAMDATA/ssh/administrators_authorized_keys
debug3: reprocess config:88 setting TrustedUserCAkeys PROGRAMDATA/ssh/trusted-user-ca-keys.pem
debug3: mm_answer_pwnamallow: sending MONITOR_ANS_PWNAM: 1
debug3: mm_request_send entering: type 9
debug2: monitor_read: 8 used once, disabling now
debug2: input_userauth_request: setting up authctxt for MYUSER [preauth]
debug3: mm_inform_authserv entering [preauth]
debug3: mm_request_send entering: type 4 [preauth]
debug2: input_userauth_request: try method none [preauth]
debug3: userauth_finish: failure partial=0 next methods="publickey,keyboard-interactive" [preauth]
debug3: send packet: type 51 [preauth]
debug3: receive packet: type 50 [preauth]
debug1: userauth-request for user MYUSER service ssh-connection method publickey [preauth]
debug1: attempt 1 failures 0 [preauth]
debug2: input_userauth_request: try method publickey [preauth]
userauth_pubkey: unsupported public key algorithm: rsa-sha2-256-cert-v01@openssh.com [preauth]
debug2: userauth_pubkey: authenticated 0 pkalg rsa-sha2-256-cert-v01@openssh.com [preauth]
debug3: userauth_finish: failure partial=0 next methods="publickey,keyboard-interactive" [preauth]
debug3: send packet: type 51 [preauth]
debug3: receive packet: type 50 [preauth]
debug1: userauth-request for user MYUSER service ssh-connection method publickey [preauth]
debug1: attempt 2 failures 1 [preauth]
debug2: input_userauth_request: try method publickey [preauth]
debug1: userauth_pubkey: test pkalg rsa-sha2-256 pkblob RSA SHA256:vREtEXRtCNltN3de4Io/FluUtKUyxOFicNl7NjcHhpQ [preauth]
debug3: mm_key_allowed entering [preauth]
debug3: mm_request_send entering: type 22 [preauth]
debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth]
debug3: mm_request_receive_expect entering: type 23 [preauth]
debug3: mm_request_receive entering [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 4
debug3: mm_answer_authserv: service=ssh-connection, style=
debug2: monitor_read: 4 used once, disabling now
debug3: mm_request_receive entering
debug3: monitor_read: checking request 22
debug3: mm_answer_keyallowed entering
debug3: mm_answer_keyallowed: key_from_blob: 0000016ED1C6AE70
debug1: trying public key file PROGRAMDATA/ssh/administrators_authorized_keys
debug3: Failed to open file:C:/ProgramData/ssh/administrators_authorized_keys error:2
debug1: Could not open authorized keys 'PROGRAMDATA/ssh/administrators_authorized_keys': No such file or directory
debug3: mm_answer_keyallowed: publickey authentication test: RSA key is not allowed
Failed publickey for MYUSER from 192.168.0.211 port 34466 ssh2: RSA SHA256:vREtEXRtCNltN3de4Io/FluUtKUyxOFicNl7NjcHhpQ
debug3: mm_request_send entering: type 23
debug2: userauth_pubkey: authenticated 0 pkalg rsa-sha2-256 [preauth]
debug3: userauth_finish: failure partial=0 next methods="publickey,keyboard-interactive" [preauth]
debug3: send packet: type 51 [preauth]
debug3: receive packet: type 50 [preauth]
debug1: userauth-request for user MYUSER service ssh-connection method keyboard-interactive [preauth]
debug1: attempt 3 failures 2 [preauth]
debug2: input_userauth_request: try method keyboard-interactive [preauth]
debug1: keyboard-interactive devs [preauth]
debug1: auth2_challenge: user=MYUSER devs= [preauth]
debug1: kbdint_alloc: devices '' [preauth]
debug2: auth2_challenge_start: devices [preauth]
debug3: userauth_finish: failure partial=0 next methods="publickey,keyboard-interactive" [preauth]
debug3: send packet: type 51 [preauth]
Connection closed by authenticating user MYUSER 192.168.0.211 port 34466 [preauth]
debug1: do_cleanup [preauth]
debug3: ReadFileEx() ERROR:109, io:0000016ED1C67770
debug1: monitor_read_log: child log fd closed
debug3: mm_request_receive entering
debug1: do_cleanup
debug1: Killing privsep child 7928
sshd.exe exited on KUBERNETES1 with error code 255.

C:\PSTools>

[keke8273]

Hi all, could somebody confirm if certificate base authentication is supported by Win32-OpenSSH?