我试着跟随这篇文章，但是我在尝试ssh到datanode服务器时出错了，有什么问题吗？（这个命令就在hadoop上面）请帮助我找出问题所在

$ ssh -v ubuntu@ec2-xx-xx-xx-xxx.us-xxxxxx-2.compute.amazonaws.com

debug1: Reading configuration data /home/ubuntu/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to ec2-xx-xx-xxx-xxx.us-xxxx-2.compute.amazonaws.com [xx-xx-xx-xx] port 22.
debug1: Connection established.
debug1: identity file /home/ubuntu/.ssh/id_rsa type 1
debug1: identity file /home/ubuntu/.ssh/id_rsa-cert type -1
debug1: identity file /home/ubuntu/.ssh/id_dsa type -1
debug1: identity file /home/ubuntu/.ssh/id_dsa-cert type -1
debug1: identity file /home/ubuntu/.ssh/id_ecdsa type -1
debug1: identity file /home/ubuntu/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/ubuntu/.ssh/id_ed25519 type -1
debug1: identity file /home/ubuntu/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.7
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.7
debug1: match: OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.7 pat OpenSSH_6.6.1* compat 0x04000000
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5-etm@openssh.com none
debug1: kex: client->server aes128-ctr hmac-md5-etm@openssh.com none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ECDSA 8c:b6:90:4a:5d:97:8c:47:e1:96:dd:42:82:4a:56:a5
debug1: Host 'ec2-xx-xxx-xxx-xx.us-west-2.compute.amazonaws.com' is known and matches the ECDSA host key.
debug1: Found key in /home/ubuntu/.ssh/known_hosts:3
debug1: ssh_ecdsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/ubuntu/.ssh/id_rsa
debug1: Authentications that can continue: publickey
debug1: Trying private key: /home/ubuntu/.ssh/id_dsa
debug1: Trying private key: /home/ubuntu/.ssh/id_ecdsa
debug1: Trying private key: /home/ubuntu/.ssh/id_ed25519
debug1: No more authentication methods to try.
Permission denied (publickey).

.ssh文件内容：

-rw------- 1 ubuntu ubuntu  400 Aug 24 04:35 authorized_keys_bkp
-rw-rw-r-- 1 ubuntu ubuntu    0 Aug 25 02:37 authorized_keys’
-rw-rw-r-- 1 ubuntu ubuntu 1692 Aug 25 02:39 AmitKeyPari_Oregon.pem
drwxrwxr-x 2 ubuntu ubuntu 4096 Aug 25 02:39 config
-rw-r--r-- 1 ubuntu ubuntu  405 Aug 25 02:40 id_rsa.pub
-rw------- 1 ubuntu ubuntu 1766 Aug 25 02:40 id_rsa
-rw------- 1 ubuntu ubuntu  805 Aug 25 02:40 authorized_keys
-rw-r--r-- 1 ubuntu ubuntu  444 Aug 25 02:41 known_hosts