Connecting ubuntu systems via SSH server

We can connect ubuntu systems using openssh-server.It helps to access other system with your system.
For that install openssh-server which system you want to access.

In command you install via below given commands...

                           sudo -apt|get install openssh-server
                            sudo update-rc.d ssh defaults

When I try to connect to the System with SSH using

ssh username@hostname
or
ssh username@ipaddress

Example:
ssh  raja@192.168.1.73