First update the apt source list using apt-get update command.

apt-get update

Then install the openssh server on debian using apt-get install command.

apt-get install openssh-server

Now start and enable the debian ssh server to start at system reboot.

systemctl start ssh.service

systemctl enable ssh.service

Also run netstat command to make sure that ssh port 22 is open and running.

netstat -tulnp | grep 22

You can view the status of the ssh server using systemctl command.

systemctl status ssh.service

Pripojenie na SSH server

ssh <username> @<Server-IPAddress>