The Secure Shell: The Definitive Guide.
https://docstore.mik.ua/orelly/networking_2ndEd/ssh/index.htm
https://download.csdn.net/download/sunpai/7115131
https://support.suso.com/supki/SSH_Tutorial_for_Linux
https://www.ssh.com/ssh/scp/
https://en.wikipedia.org/wiki/Secure_Shell
https://www.thegeekstuff.com/2008/05/5-basic-linux-ssh-client-commands/