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I'm trying to set up OpenSSH on a Windows server to test SSH.NET but I need to authenticate using a key, rather than a password, and I'm having problems doing so.

I can login to the OpenSSH server via PuTTY using a username and password, but when I set up the private key in PuTTY, I keep getting error: Server refused our key

My steps:

  • Windows Server:
    1. Installed OpenSSH server
    2. Started OpenSSH server and Agent services
    3. Copied the public key within PuTTY's Key Generator textbox on my workstation into %UserProfile%\.ssh\authorized_keys
      • I found this article, but it's about connecting to a Linux server and using commands such as chmod 700 ~/.ssh; I'm not sure whether it could be related to this or if this should be done on a Windows server.
    4. Restarted OpenSSH server and Agent
  • Workstation:
    1. Installed PuTTY on my workstation
    2. Ran PuTTY Key Generator and generate public and private keys
    3. Saved my public and private keys
    4. Opened PuTTY and added the private key file under the SSH|Auth section
    5. Clicked Open, received error Server refused our key, and am prompted for the password

Any suggestions/ideas?


  • sshd_config:

    # This is the sshd server system-wide configuration file.
    # See sshd_config(5) for more information.
    
    # The strategy used for options in the default sshd_config shipped with
    # OpenSSH is to specify options with their default value where possible,
    # but leave them commented.  Uncommented options override the default value.
    
    # override default of no subsystems
    Subsystem sftp              sftp-server.exe
    
    # Logging
    SyslogFacility              LOCAL0
    LogLevel                    DEBUG3
    
    # The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2
    # but this is overridden so installations will only check .ssh/authorized_keys
    AuthorizedKeysFile          .ssh/authorized_keys
    
    Match Group                 administrators
      AuthorizedKeysFile        __PROGRAMDATA__/ssh/administrators_authorized_keys
    
    #Port                        22
    #AddressFamily               any
    #ListenAddress               0.0.0.0
    #ListenAddress               ::
    
    #HostKey                     __PROGRAMDATA__/ssh/ssh_host_rsa_key
    #HostKey                     __PROGRAMDATA__/ssh/ssh_host_dsa_key
    #HostKey                     __PROGRAMDATA__/ssh/ssh_host_ecdsa_key
    #HostKey                     __PROGRAMDATA__/ssh/ssh_host_ed25519_key
    
    # Ciphers and keying
    #RekeyLimit                  default none
    
    # Logging
    #SyslogFacility              AUTH
    #LogLevel                    INFO
    
    # Authentication:
    #LoginGraceTime              2m
    #PermitRootLogin             prohibit-password
    #StrictModes                 yes
    #MaxAuthTries                6
    #MaxSessions                 10
    
    #PubkeyAuthentication        yes
    
    #AuthorizedPrincipalsFile    none
    
    # For this to work you will also need host keys in %programData%/ssh/ssh_known_hosts
    #HostbasedAuthentication     no
    
    # Change to yes if you don't trust ~/.ssh/known_hosts for HostbasedAuthentication
    #IgnoreUserKnownHosts        no
    
    # Don't read the user's ~/.rhosts and ~/.shosts files
    #IgnoreRhosts                yes
    
    # To disable tunneled clear text passwords, change to no here!
    #PasswordAuthentication      yes
    #PermitEmptyPasswords        no
    
    # GSSAPI options
    #GSSAPIAuthentication        no
    
    #AllowAgentForwarding        yes
    #AllowTcpForwarding          yes
    #GatewayPorts                no
    #PermitTTY                   yes
    #PrintMotd                   yes
    #PrintLastLog                yes
    #TCPKeepAlive                yes
    #UseLogin                    no
    #PermitUserEnvironment       no
    #ClientAliveInterval         0
    #ClientAliveCountMax         3
    #UseDNS                      no
    #PidFile                     /var/run/sshd.pid
    #MaxStartups                 10:30:100
    #PermitTunnel                no
    #ChrootDirectory             none
    #VersionAddendum             none
    
    # no default banner path
    #Banner                      none
    
    # Example of overriding settings on a per-user basis
    #Match User                  anoncvs
    #  AllowTcpForwarding        no
    #  PermitTTY                 no
    #  ForceCommand              cvs server
    
  • Log:
    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
    debug3: spawning "E:\\ssh\\OpenSSH-Win64\\sshd.exe" -R
    debug3: send_rexec_state: entering fd = 8 config len 291
    debug3: ssh_msg_send: type 0
    debug3: send_rexec_state: done
    debug1: inetd sockets after dupping: 4, 4
            Connection from x.x.x.72 port 53482 on x.x.x.x port 22
    debug1: Local version string SSH-2.0-OpenSSH_for_Windows_8.1
    debug1: Remote protocol version 2.0, remote software version WinSCP_release_5.17.6
    debug1: no match: WinSCP_release_5.17.6
    debug2: fd 4 setting O_NONBLOCK
    debug3: spawning "E:\\ssh\\OpenSSH-Win64\\sshd.exe" -y
    debug2: Network child is on pid 7688
    debug3: send_rexec_state: entering fd = 6 config len 291
    debug3: ssh_msg_send: type 0
    debug3: send_rexec_state: done
    debug3: ssh_msg_send: type 0
    debug3: ssh_msg_send: type 0
    debug3: preauth child monitor started
    debug1: list_hostkey_types: rsa-sha2-512,rsa-sha2-256,ssh-rsa,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,[email protected],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: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
    debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected] [preauth]
    debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected] [preauth]
    debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1 [preauth]
    debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1 [preauth]
    debug2: compression ctos: none,[email protected] [preauth]
    debug2: compression stoc: none,[email protected] [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: [email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,rsa2048-sha256,rsa1024-sha1,diffie-hellman-group1-sha1 [preauth]
    debug2: host key algorithms: ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-rsa,ssh-dss [preauth]
    debug2: ciphers ctos: aes256-ctr,aes256-cbc,[email protected],aes192-ctr,aes192-cbc,aes128-ctr,aes128-cbc,[email protected],3des-ctr,3des-cbc,blowfish-ctr,blowfish-cbc,arcfour256,arcfour128 [preauth]
    debug2: ciphers stoc: aes256-ctr,aes256-cbc,[email protected],aes192-ctr,aes192-cbc,aes128-ctr,aes128-cbc,[email protected],3des-ctr,3des-cbc,blowfish-ctr,blowfish-cbc,arcfour256,arcfour128 [preauth]
    debug2: MACs ctos: hmac-sha2-256,hmac-sha1,hmac-sha1-96,hmac-md5,[email protected],[email protected],[email protected],[email protected] [preauth]
    debug2: MACs stoc: hmac-sha2-256,hmac-sha1,hmac-sha1-96,hmac-md5,[email protected],[email protected],[email protected],[email protected] [preauth]
    debug2: compression ctos: none,zlib,[email protected] [preauth]
    debug2: compression stoc: none,zlib,[email protected] [preauth]
    debug2: languages ctos:  [preauth]
    debug2: languages stoc:  [preauth]
    debug2: first_kex_follows 0  [preauth]
    debug2: reserved 0  [preauth]
    debug1: kex: algorithm: [email protected] [preauth]
    debug1: kex: host key algorithm: ssh-ed25519 [preauth]
    debug1: kex: client->server cipher: aes256-ctr MAC: hmac-sha2-256 compression: none [preauth]
    debug1: kex: server->client cipher: aes256-ctr MAC: hmac-sha2-256 compression: none [preauth]
    debug1: expecting SSH2_MSG_KEX_ECDH_INIT [preauth]
    debug3: receive packet: type 30 [preauth]
    debug3: mm_sshkey_sign entering [preauth]
    debug3: mm_request_send entering: type 6 [preauth]
    debug3: mm_sshkey_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: KEX signature 000000EAA5308050(83)
    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 out after 4294967296 blocks [preauth]
    debug1: SSH2_MSG_NEWKEYS sent [preauth]
    debug1: expecting SSH2_MSG_NEWKEYS [preauth]
    debug3: receive packet: type 21 [preauth]
    debug1: SSH2_MSG_NEWKEYS received [preauth]
    debug2: set_newkeys: mode 0 [preauth]
    debug1: rekey in 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 [email protected] 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 291
    debug3: checking match for 'Group administrators' user mycompany\\myuser host x.x.x.72 addr x.x.x.72 laddr x.x.x.x lport 22
    debug3: lookup_principal_name: Successfully discovered explicit principal name: 'mycompany\\myuser'=>'[email protected]'
    debug3: LsaLogonUser Succeeded (Impersonation: 0)
    debug1: user mycompany\\myuser matched group list administrators at line 89
    debug3: match found
    debug3: reprocess config:90 setting AuthorizedKeysFile __PROGRAMDATA__/ssh/administrators_authorized_keys
    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 [email protected] [preauth]
    debug3: mm_inform_authserv entering [preauth]
    debug3: mm_request_send entering: type 4 [preauth]
    debug2: input_userauth_request: try method none [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: user_specific_delay: user specific delay 0.000ms [preauth]
    debug3: ensure_minimum_time_since: elapsed 58.995ms, delaying 50.873ms (requested 6.867ms) [preauth]
    debug3: userauth_finish: failure partial=0 next methods="publickey,password,keyboard-interactive" [preauth]
    debug3: send packet: type 51 [preauth]
    debug3: receive packet: type 50 [preauth]
    debug1: userauth-request for user [email protected] service ssh-connection method publickey [preauth]
    debug1: attempt 1 failures 0 [preauth]
    debug2: input_userauth_request: try method publickey [preauth]
    debug2: userauth_pubkey: valid user [email protected] querying public key ssh-rsa AAAAB3Nza2EAAAABJQAAAQEAoTH5Dd4wzYkYr6WT/IeK+Lwy33KCHXJMxBvKrnaiLq8zamuKSibwu7xn5TUac2ZWXnQ== [preauth]
    debug1: userauth_pubkey: test pkalg ssh-rsa pkblob RSA SHA256:ERmTsG3EdOUU6A5/1iqPYX3+E3aTF5Ke+5zOs [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 22
    debug3: mm_answer_keyallowed entering
    debug3: mm_answer_keyallowed: key_from_blob: 000000EAA53A75C0
    debug1: trying public key file __PROGRAMDATA__/ssh/administrators_authorized_keys
    debug3: Bad permissions. Try removing permissions for user: NT AUTHORITY\\Authenticated Users (S-1-5-11) on file C:/ProgramData/ssh/administrators_authorized_keys.
            Authentication refused.
    debug3: mm_answer_keyallowed: publickey authentication test: RSA key is not allowed
            Failed publickey for [email protected] from x.x.x.72 port 53482 ssh2: RSA SHA256:ERmTsG3EdOUU6A5/1iqPYX3+E3aTF5Ke+5zOs
    debug3: mm_request_send entering: type 23
    debug2: userauth_pubkey: authenticated 0 pkalg ssh-rsa [preauth]
    debug3: user_specific_delay: user specific delay 0.000ms [preauth]
    debug3: ensure_minimum_time_since: elapsed 2.030ms, delaying 4.837ms (requested 6.867ms) [preauth]
    debug3: userauth_finish: failure partial=0 next methods="publickey,password,keyboard-interactive" [preauth]
    debug3: send packet: type 51 [preauth]
    debug3: receive packet: type 50 [preauth]
    debug1: userauth-request for user [email protected] service ssh-connection method keyboard-interactive [preauth]
    debug1: attempt 2 failures 1 [preauth]
    debug2: input_userauth_request: try method keyboard-interactive [preauth]
    debug1: keyboard-interactive devs  [preauth]
    debug1: auth2_challenge: [email protected] devs= [preauth]
    debug1: kbdint_alloc: devices '' [preauth]
    debug2: auth2_challenge_start: devices  [preauth]
    debug3: user_specific_delay: user specific delay 0.000ms [preauth]
    debug3: ensure_minimum_time_since: elapsed 0.000ms, delaying 6.867ms (requested 6.867ms) [preauth]
    debug3: userauth_finish: failure partial=0 next methods="publickey,password,keyboard-interactive" [preauth]
    debug3: send packet: type 51 [preauth]
            Connection closed by authenticating user [email protected] x.x.x.72 port 53482 [preauth]
    debug1: do_cleanup [preauth]
    debug3: mm_request_receive entering
    debug1: do_cleanup
    debug1: Killing privsep child 7688
    
21
  • Are you trying to connect to an administrator account? What are the current file permissions of the authorized_keys file? Commented Jun 5, 2020 at 8:55
  • And it's c:\users\myuser\.ssh not c:\users\myuser.ssh (though I assume it's a typo only). + For Win32-OpenSSH specific instructions, see my guide at winscp.net/eng/docs/… Commented Jun 5, 2020 at 9:08
  • @user1686 As suggested in a post, I've removed all users allowed to access this file except for myself and I've got full permission on this file.
    – Thierry
    Commented Jun 5, 2020 at 9:27
  • 1
    Domain is not relevant here. If you are a local administrator, then you need to use a different authorized keys file. Read the link I have posted before. Commented Jun 5, 2020 at 13:37
  • 1
    @Thierry Glad to know the problem is solved. Happy SSH'ing. Commented Jun 10, 2020 at 11:53

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