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OS Linux: Centos, Debian, Ubuntu, Cloudlinux;Amazon Web Services (AWS);Web servers: HAProxy, Nginx, Apache, Tomcat, php-fpm;DNS servers: bind, powerdns;FTP servers: Proftpd, sftpd, pure-ftpd;Monitoring: Zabbix, Nagios, Munin;OpenVPN, VLAN, routing;Soft routers: pfSense, VyOs;Web hosting panels: ISPmanager, cPanel, DirectAdmin, VestaCP, CWP, Webmin, I-MSCP, SolusVM;Billing hosting system: WHMCS, Billmanager;Zimbra mail server;Ansible;Git, Jenkins CI;Proxmox;