how to install ssh serve in Ubuntu

OpenSSh is opensource ssh server in Linux.

Ubuntu SSHD Installation

Type the following two command to install both ssh client and server:
# sudo apt-get install openssh-server openssh-client

SSHD Configuration

To be frank your server is ready by default. Just test it from your home computer or from same system with the command:
# ssh localhost
OR
# ssh user@your-server-ip-address

How do I use ssh client?

Assuming that your server hostname is userver.kasun.com and username is kasun, you need to type the following command:
# ssh kasun@userver.kasun.com
To stop ssh server, enter:
# sudo /etc/init.d/ssh stop
To start sshs server, enter:
# sudo /etc/init.d/ssh start
To restart ssh server, enter:
# sudo /etc/init.d/ssh restart