SSH connection is very secure remote connectivity, you can install openssh-server in Ubuntu using agt-get command,

# sudo apt-get install openssh-server 

If you could not connect your system remotely need to check your sshd_config file,

By default OpenSSH Server setting in Debian, Ubuntu and related operating system is to
deny password-based login for root user and allow only key-based login

Open the /etc/ssh/sshd_config file and update the following setting,
# sudo gedit /etc/ssh/sshd_config

# vim /etc/ssh/sshd_config

# Authentication:
PermitRootLogin without-password

Change to
# Authentication:
PermitRootLogin  yes

# service ssh  restart

ssh stop/waiting
ssh start/running, process 9474