Secure Shell

Secure Shell (SSH) is a cryptographic network protocol for operating network services such as remote command-line, login, and remote command execution over an unsecured network in a secure way. SSH provides a secure channel over an unsecured network by using a client–server architecture, connecting an SSH client application with an SSH server. SSH is generally used to access Unix-like operating systems, but it can also be used on Microsoft Windows. Windows 10 uses OpenSSH as its default SSH client and SSH server.

SSH was designed as a replacement for Telnet and for unsecured remote shell protocols which would send information, notably passwords, in plaintext, rendering them susceptible to interception and recognition. The encryption used by SSH is intended to provide confidentiality and integrity of data over an unsecured network such as the Internet. While Telnet was once widely used by administrators for remote management, it does not offer the security mechanisms like SSH, which establishes a secure connection from the host to the remote host.

Linux Secure Shell Support for Remote Login

Modern Ubuntu / Mint

I don't know why they do not include SSH by default. Allows remote secure terminal shell connection.

sudo apt install openssh-server openssh-client 
sudo service ssh start

Note: Added 10/17/2016 old less secure or compromised cyphers no longer configured, may cause connection problems with legacy ssh clients such as SecureCRT. ref: https://blog.hqcodeshop.fi/archives/245-SSH-connection-fails.html