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I am trying to login to the remote server using ssh client from ubuntu, but public key authentication does not work and asks me to enter ssh password.

Here are the debug report, don't know what does it means..

OpenSSH_6.6.1, OpenSSL 1.0.1f 6 Jan 2014
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to shell.gridhost.co.uk [185.52.26.190] port 22.
debug1: Connection established.
debug1: identity file /home/dipengrg/.ssh/id_rsa type 1
debug1: identity file /home/dipengrg/.ssh/id_rsa-cert type -1
debug1: identity file /home/dipengrg/.ssh/id_dsa type -1
debug1: identity file /home/dipengrg/.ssh/id_dsa-cert type -1
debug1: identity file /home/dipengrg/.ssh/id_ecdsa type -1
debug1: identity file /home/dipengrg/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/dipengrg/.ssh/id_ed25519 type -1
debug1: identity file /home/dipengrg/.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-2ubuntu2.3
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH_5* compat 0x0c000000
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<3072<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 31:62:64:d1:f6:64:a7:4f:68:fe:80:97:34:37:0b:be
debug1: Host 'shell.gridhost.co.uk' is known and matches the RSA host key.
debug1: Found key in /home/dipengrg/.ssh/known_hosts:1
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_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Next authentication method: gssapi-keyex
debug1: No valid Key exchange context
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure. Minor code may provide more information
No Kerberos credentials available

debug1: Unspecified GSS failure. Minor code may provide more information
No Kerberos credentials available

debug1: Unspecified GSS failure. Minor code may provide more information

debug1: Unspecified GSS failure. Minor code may provide more information
No Kerberos credentials available

debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/dipengrg/.ssh/id_rsa
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Trying private key: /home/dipengrg/.ssh/id_dsa
debug1: Trying private key: /home/dipengrg/.ssh/id_ecdsa
debug1: Trying private key: /home/dipengrg/.ssh/id_ed25519
debug1: Next authentication method: password
  • did you generate the private/public key pair locally and upload public key to the server? – the_velour_fog Oct 4 '15 at 10:31
  • a common issue is file permissions. ssh will skip over things (like checking for matching keys) if the file (and parent directory) permissions are insecure. – Skaperen Oct 4 '15 at 10:36
  • @user4668401 yes i did that, and saved the my local public key on the remote server in /.ssh/authorized_keys. – Dipendra Gurung Oct 4 '15 at 10:41
  • @Skaperen I have set the .ssh/ permission as 700 and .ssh/authorized_keys as 640 on the remote server. – Dipendra Gurung Oct 4 '15 at 10:43
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authorized_keys file must be no less secure than 600, try running

$ chmod 600 $ ~/.ssh/authorized_keys

so you should end up with

-rw------- 1 serverAdmin serverAdmin  802 Nov 25 13:54 authorized_keys

(obviously serverAdmin should be replaced with the user account you are running on the remote server)
also .ssh directory cannot be less secure than 755 e.g.

drwx------ 2 serverAdmin serverAdmin  4096 Jul 29 00:30 .ssh

I find its best to use ssh-copy-id to get public key onto remote server as it handles privileges on the remote files

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