SSH, or Secure Shell, is a protocol used to securely log onto remote systems.
>  a program used for logging or executing commands on a remote server.

- connecting to a remote server
`ssh username@remote_host`

- connecting to a remote server with specific port
`ssh username@remote_host` -P 2222

- ssh tunneling
`ssh -D 9999 -C username@remote_host`
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