DevOps: Jenkins, Git, GitHubLinux: RedHat/CentOS, Debian/Ubuntu.Virtualization: VMWare, KVM, Docker, LXC, Proxmox.

Cloud: Google Cloud, Azure, Hetzner Cloud.

Monitoring: New Relic, Zabbix, ELK, Cacti.Web: Apache (and/or) Nginx, Haproxy.

Mail: Postfix, Dovecot.DNS: Bind.Databases: MySQL, MariaDB, MongoDB, PostgreSQL.

VPN: OpenVPN, PPTPDevelopment: Python, Bash.