I am trying to configure SSHD to allow public key authentication under Cygwin on Windows Server 2012. Currently my problem is access being denied. I have confirmed that my public key is saved as a single line in authorized_keys and authorized_keys2 in the user's .ssh directory. Below you will find the command I used to connedt, the verbose output of my attempt to connect with SSH using my private key, and my SSHD configuration. The private key I'm attempt to use is in RSA PEM format.

I have also tried adding RSAAuthentication Yes to my configuration, but doing cause SSHD to fail on startup.

When RSAAuthentication YES is in the SSHD config I get he below error.

cygrunsrv: Error starting a service: QueryServiceStatus: Win32 error 1062: The service has not been started.

SSH Connection Command

ssh -v -i id_rsa.pem <USER>@<SERVER ADDRESS>

SSHD Configuration

PasswordAuthentication no
UsePAM no
PubkeyAuthentication yes

Verbose Output

OpenSSH_6.2p2, OSSLShim 0.9.8r 8 Dec 2011
debug1: Reading configuration data /etc/ssh_config
debug1: /etc/ssh_config line 20: Applying options for *
debug1: /etc/ssh_config line 53: Applying options for *
debug1: Connecting to ec2-54-186-180-177.us-west-2.compute.amazonaws.com [] port 22.
debug1: Connection established.
debug1: identity file id_rsa.pem type -1
debug1: identity file id_rsa.pem-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.2
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH_5*
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Server host key: RSA a6:a5:57:ef:09:14:7b:0b:cc:29:7b:01:fa:ac:c8:ea
debug1: Host 'ec2-54-186-180-177.us-west-2.compute.amazonaws.com' is known and matches the RSA host key.
debug1: Found key in /Users/cyotee/.ssh/known_hosts:6
Warning: the RSA host key for 'ec2-54-186-180-177.us-west-2.compute.amazonaws.com' differs from the key for the IP address ''
Offending key for IP in /Users/cyotee/.ssh/known_hosts:5
Matching host key in /Users/cyotee/.ssh/known_hosts:6
Are you sure you want to continue connecting (yes/no)? yes
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Trying private key: id_rsa.pem
debug1: read PEM private key done: type RSA
debug1: Authentications that can continue: publickey
debug1: No more authentication methods to try.
Permission denied (publickey).
  • 2
    sshd and ssh are fussy about the permissions of the file containing the private key. They must not be group or world readable. I'm unsure of how this translates to Cygwin.
    – LawrenceC
    Apr 13, 2014 at 0:47
  • 1
    You need to take a look at the server side. The client looks to be running perfectly fine.
    – Daniel B
    Apr 13, 2014 at 1:03
  • Try checking the log on server side. It is usually located at /var/log/sshd.log inside of cygwin.
    – Squeezy
    Apr 14, 2014 at 18:03

2 Answers 2


In my experience, the problem is usually incorrect file permissions on the server side. Try modifying file permissions accordingly.


chmod 700 ~USERNAME/.ssh

chmod 600 ~USERNAME/.ssh/authorized_keys


It would be of great help if you could show us what the end of your public key is it should be something like <user>@<host> for both the one on your computer (in the file named something like <filename>.pub under /.ssh/) and the one on the remote server that you copied into the authorized_keys), also the computer you are using to connect can you also show what the command hostname outputs.

If you copied the key from a different computer this is highly not recommended and might be your issue...

  • 1
    The last field of the public key is just a comment.
    – Kenster
    Jul 17, 2014 at 15:45

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