Windows ssh: Permission denied (publickey)

Question

I am trying to ssh to the remote client using a public key but I keep getting the permission denied (publickey) error and can't solve it. I have tried all the other solutions online, but it still won't work. I have replaced some information with * and ip_add. How do I resolve this issue?

    PS C:\WINDOWS\system32> ssh -v -i C:/Users/*/.ssh/id_rsa administrator@ip_add
    OpenSSH_for_Windows_7.6p1, LibreSSL 2.6.4
    debug1: Connecting to ip_add [ip_add] port 22.
    debug1: Connection established.
    debug1: identity file C:/Users/*/.ssh/id_rsa type 0
    debug1: key_load_public: No such file or directory
    debug1: identity file C:/Users/*/.ssh/id_rsa-cert type -1
    debug1: Local version string SSH-2.0-OpenSSH_for_Windows_7.6
    debug1: Remote protocol version 2.0, remote software version OpenSSH_for_Windows_8.1
    debug1: match: OpenSSH_for_Windows_8.1 pat OpenSSH* compat 0x04000000
    debug1: Authenticating to ip_add:22 as 'administrator'
    debug1: SSH2_MSG_KEXINIT sent
    debug1: SSH2_MSG_KEXINIT received
    debug1: kex: algorithm: curve25519-sha256
    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:qjxnj9GZZ6kvey+qvHsEoJYnLTz4N82DtnmFMjRlrq8
    debug1: Host '192.168.1.135' is known and matches the ECDSA host key.
    debug1: Found key in C:\\Users\\*/.ssh/known_hosts:2
    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: pubkey_prepare: ssh_get_authentication_socket: No such file or directory
    debug1: SSH2_MSG_EXT_INFO received
    debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
    debug1: SSH2_MSG_SERVICE_ACCEPT received
    debug1: Authentications that can continue: publickey
    debug1: Next authentication method: publickey
    debug1: Offering public key: RSA SHA256:+ymSxB9gd+AJe9wYj0WgW70Qk+x4fWxEQhk1JCQyKWE C:/Users/*/.ssh/id_rsa
    debug1: Authentications that can continue: publickey
    debug1: No more authentication methods to try.
    administrator@ip_add: Permission denied (publickey).

Answer 1

I got the same error trying to connect from a Win 11 machine to a Win 10 using authorization keys. It worked just fine with password, but not with a key.

Most important step, enable output logs on the server so you know what to fix. That took me a while before I found out it was even possible.

Add this to sshd_config on the server and it should output a text file under %programdata%\ssh\logs

SyslogFacility LOCAL0
LogLevel Debug3

For me the error was the file ownership and permissions of the file authorized_keys under the \users\<myuser>/.ssh/ folder. My user had permissions to the file and I thought that must be enough. The logs said otherwise. I had to change the file ownership to my user and remove all other user permissions except for my user and system.

I thought it was merely a recommendation. But apparently this is a MUST. Wasted hours due to this. Oh well.