SSH Permission denied (publickey) on Raspberry Pi

Question

I used to be able to establish a ssh connection to my Raspberry Pi but suddenly it failed on me.

The usual way to log in is just

ssh [email protected]

and it would request a password.

But today when I come back from work, suddenly it denied my access and it won't even ask for a password. Pretty sure no one mess with my Raspberry Pi as it is stored in a very secure location, my family members will not and have no intention of using it.

Note:

• Checked with the connection, port is available to access
• I have tried to start fresh by removing the known_host file and regenerate the key to no avail.

Here's the error log

OpenSSH_7.6p1, LibreSSL 2.6.2
debug1: Reading configuration data /Users/rexlow/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 48: Applying options for *
debug1: Connecting to 192.168.0.140 port 22.
debug1: Connection established.
debug1: key_load_public: No such file or directory
debug1: identity file /Users/rexlow/.ssh/id_rsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/rexlow/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/rexlow/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/rexlow/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/rexlow/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/rexlow/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/rexlow/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/rexlow/.ssh/id_ed25519-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.6
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.7p1 Raspbian-5+deb8u4
debug1: match: OpenSSH_6.7p1 Raspbian-5+deb8u4 pat OpenSSH* compat 0x04000000
debug1: Authenticating to 192.168.0.140:22 as 'pi'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: [email protected]
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:MXY6qgs+k9+OXkZgXta3cghQaxXN+ATz12dBKSuFE3E
debug1: Host '192.168.0.140' is known and matches the ECDSA host key.
debug1: Found key in /Users/rexlow/.ssh/known_hosts:1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /Users/rexlow/.ssh/id_rsa
debug1: Trying private key: /Users/rexlow/.ssh/id_dsa
debug1: Trying private key: /Users/rexlow/.ssh/id_ecdsa
debug1: Trying private key: /Users/rexlow/.ssh/id_ed25519
debug1: No more authentication methods to try.
[email protected]: Permission denied (publickey).

Solution

Was able to get a monitor and access the /etc/ssh/sshd_config file.

Found the culprit,

PasswordAuthentication no

Changed to yes and I am able to connect again.

Comments

[nKn]

Does using ssh -o PreferredAuthentications=password -o PubkeyAuthentication=no [email protected] make any difference?

[Rex Low]

it still denied my attempt to connect...

[nKn]

It seems some configuration issue on the remote system, then. Could you login through console to the Raspberry Pi and post your /etc/ssh/sshd_config file?

[Rex Low]

Hmm... I do not have a monitor at the moment, only have my MacBook... Is there another way?