Systems: Debian, Ubuntu, CentOS

Web: Apache, Nginx, PHP, PHP-FPM, Memcached, ISPmanager

DBMS: MySQL, PostgreSQL, MariaDB

Automatization: Ansible,Puppet,Terraform, Docker

Software: postfix, exim, dovecot, bind, squid, samba, ftp servers, ssh, openssl, openVPN, etc.

Version control systems: Git, GitLab

CI/CD: Jenkins, gitlab-ci

Cloud: AWS, GoogleCloud, Digital Ocean

Scripting: Shell

Virtualization: kvm, openvz, lxd, proxmox, vmware

Firewall: IPTABLES

Monitoring: Zabbix, ELK Stack

Backup: Bacula, sanoid

Networking/Protocols: TCP/IP, UDP, ICMP, DNS, DHCP, SNMP, HTTP/HTTPS, SMTP, NTP, VPN, FTP, IP Routing, etc.

Creating networks based on vlan, setting switches and routers