Linux server administration (CentOS 6.x, 7.x, Debian, Ubuntu): install/config/deploy/tweaking/optimization/security/maintenance Virtualization: OpenNebula, Proxmox (KVM/LXC/LXD), KVM, SolusVM (KVM/OpenVZ), QubesOS, Docker, Kubernetes Firewalling: Linux iptables, fail2ban, sysctl tweaking/optimization TCP/IP: static routing, port aggregation, VLAN(s), EdgeOS, EdgeRouter + EdgeSwitch Servers and services monitoring (Nagios, Icinga2 with NRPE and SNMP, Zabbix) Metrics and graphs (ElasticSearch, LogStash, Kibana, Grafana, Filebeat, Metricbeat, LibreNMS, Cacti, Centralized Syslog system) Configuration Management (Jenkins, Git, Ansible) Load Balancing (Haproxy, NGINX) Web Servers: (Apache, Nginx) Proxies: TinyProxy, Squid, sRelay, Dante's sock server Databases (MySQL, MariaDB, MariaDB Gallera Cluster, PostgreSQL) Scripting and programming: Bash, Perl (basic), Python (basic), php + MySQL (basic) Ticketing/Documentation: Jira, Confluence Version control: GitHub, BitBucket, Mercurial, SVN Other tehnologies working with: RabbitMQ, Freeswitch, Jasmin SMS Gateway, RTPEngine, NodeJS, MacOSX