SSH service is not enabled by default in Ubuntu Desktop and Ubuntu Server, but you can easily enable it just by one command.
Note: If you have installed OpenSSH Server when you install your Ubuntu Server (i.e., the software selection process page after your finish your installation of Ubuntu Server base system), just skip this post.
Log into Ubuntu server and run the command:
sudo apt-get install openssh-server
It installs OpenSSH server, and ssh remote access will be automatically enabled.
You can check its status by the command: sudo service ssh status
OpenSSH is a FREE version of the SSH connectivity tools that technical users of the Internet rely on. Users of telnet, rlogin, and ftp may not realize that their password is transmitted across the Internet unencrypted, but it is. OpenSSH encrypts all traffic (including passwords) to effectively eliminate eavesdropping, connection hijacking, and other attacks. Additionally, OpenSSH provides secure tunneling capabilities and several authentication methods, and supports all SSH protocol versions.
You can change some settings (e.g., the listening port, and root login permission) by editing the configuration file bye the command:
sudo nano /etc/ssh/sshd_config
Remember to apply the changes by restarting or reloading SSH by the command:
sudo /etc/init.d/ssh restart