First, the key generation tool puttygen.exe,
Key generation rsa2 2048, saving private and public keys.
Save yourself the private, public uploaded to the server (linux).
Key principles are: server plus random string with the public key encryption, encrypted result is sent to the client, the client with the private key to decrypt, and then send the results to decrypt the server
Verified by the server allows clients to log in.
linux file permissions operation
chmod (-R representing all recursion, the directory with the directory all) 700 filename
