• OPERATING SYSTEMS
  

Debian | Fedora | Ubuntu | FreeBSD | pfSense | FreeNAS | Solaris | OpenSolaris | Gentoo

• VIRTUALIZATION
  

Proxmox | KVM | OpenVZ | Virtualbox | VMware | HyperV

• NETWORK
  

TCP/IP (OSI) | OpenVPN | IPsec | Shorewall | iptables | bind9 | Dnsmasq | Squid | IGMP | CARP | HSRP | BGP | DHCP | DNS | SSL / TLS | IKE / ISAKMP | NTP

• MONITORING
  

Icinga | Munin | Cacti | SAR | Monit |CheckMK |Nagios | CheckMK | SNMP

• WEB SERVICES
  

Apache | Nginx | Tomcat | JBoss | Glassfish | SMTPs / IMAPs / POP3s | SFTP / TFTP / FTP | Rocketchat | Jira / Confluence | Nextcloud