- Run Putty Key Generator (puttygen.exe) and create and save keys (private as .ppk, public as .public).
- Copy the text in the window labelled “Public key for pasting into OpenSSH authorized_keys file:”
- Log onto server and past the key into a users authorized_keys file and save
- Open putty and navigate to Connection -> SSH -> Auth. Set Private key file to the .ppk file you saved in step one.
To revoke a key simply remove the relevant line from authorized_keys.
Check the permissions on your home directory, .ssh directory, and the authorized_keys file: If your ssh server is running with ‘StrictModes on’, it will refuse to use your public keys in the ~/.ssh/authorized_keys file. Your home directory should be writable only by you, ~/.ssh should be 700, and authorized_keys should be 600. Check your home direcotry is set to /home/%username% as some service accounts have different default paths for their home directory (i.e. /var/www)
Get sshd debugging to the console (or already active putty session) by executing the following command “/usr/sbin/sshd -d -p 1234” on the remote host and connecting to it on port 1234. Check your firewall allows connections to port 1234!