You can use a group policy to protect your server from known viruses that require an executable to run. For example, Sobig.F and Blaster are two fine examples.
APF Deny ALL for SSH – Limit IP Connections
APF firewall can deny ALL connections for ssh and allow only a single or select few of IPs to connect to your server. We’ll guide you through DENY ALL with APF firewall.
Allowing the root user to login directly is a major security issue, we’ll show you how to disable it so you can still login as root but just not directly, reducing the security issue.
To do this you have to create a username/password file, and a .htaccess