Server OS: Linux Debian, RedHat (CentOS), (unix) FreeBSD

monitoring: Zabbix, Icinga
dns: Bind9
mail: Postfix + Dovecot, (groupware) Zimbra
antispam: ASSP (Antispam SMTP proxy server), SpamAssassin + ClamAV
web: NGINX, Apache
databases: MariaDB (MySQL), PostgreSQL
backup: Veeam, BackupPC, shell script
virtualization: VMWare (vCenter, ESXi), KVM / QEMU, Proxmox
containers: LXC / LXD, Docker
firewall: iptables/nft, ipfw
…..LVM, mdraid, OpenVPN, SSH, Samba, NFS, rsync, Git…..


RouterOS (Mikrotik) – FW, NAT, CAPsMAN, AP, RADIUS, VPN…..

servers: HP, IBM (Lenovo), Dell, Supermicro