Disable root login
vim /etc/ssh/sshd_config
PermitRootLogin no
service sshd restart
Limit user login
vim /etc/ssh/sshd_config
AllowUsers user1 user2
service sshd restart
Change port
vim /etc/ssh/sshd_config
Port 10000
service sshd restart
Disable sftp
vim /etc/ssh/sshd_config
# Comment the following line
# Subsystem sftp /usr/lib/openssh/sftp-server
service sshd restart