i'm working as a network security engineer, i have more than 10 years experiences in following fields:
Linux servers: [ various distributions: CentOS, Gentoo, Debian, Ubuntu ]
Unix servers: [ FreeBSD, OpenBSD ]
Virtualization/Containers: [ OpenVZ, LXC, LXD, QEMU - KVM ]
Network & network security: [ Quagga, Cisco IOS, Honeypots, IDS ]
Services: [ Web (apache,nginx), Mail (postfix,dovecot,clamav,spamassassin), DNS ( PowerDNS, Bind9 ), VPN (openvpn,pptp), DB servers (MySQL, PostgreSQL)
Scripting/programming languages: [ Bash, Python, PHP, Ruby ]