Operating systems: Linux, Centos , Ubuntu , Freebsd Application/Web Servers: Apache, Nginx , Litespeed Mail Servers: Postfix , Exim , Installation and Configuration Volume Management: LVM in Linux enterprise 6 FTP Servers: VSFTP Monitoring : Nagios , Zbbix , Observium Security: SSH, SSL, TCP Wrappers , Firewall , Fail2ban Firewalls: IP tables , CSF Database: Mysql Control Panels: C panel , Plesk , C beyond , Zpanel , webmin ,Plesk