One of the first things for security of servers is to update packages for security patches:

After reading the shocking sshd backdoor story, I decided to install rkhunter for rootkit detection. Here’s the configuration changes I’ve made. In /etc/rkhunter.conf.local: And in /etc/rkhunter.conf, I have commented out MAIL_CMD and MAIL-ON-WARNING. (You need to make sure that your email works on the servers, before this.) Finally, make the rkhunter update properly by modifying…