DOS;

Windows(95-11); (AD, RDS, Office*, 1C, Medoc &etc.);

Linux (apache, postfix, openVPN, iptables & etc.);

BSD (apache, sendmail, mpd5, ipfw & etc.);

Networking (Routing & switching, TCP/IP, VLAN, DHCP, DNS & etc.);

Вiдеоспостереження*