Installation, configuration and maintenance of software / servers on a Linux system (the main Debian / Ubuntu system, in addition, but very rarely OpenSUSE, CentOS).
Often served services: Apache, Nginx, PHP, MySQL, FTP (vsftpd), Mail-server (Dovecot + Postfix + Roundcube), SVN / GIT, Asterisk (VoIP / Vicidial), SMS-Server for GoIPh Gateways, Samba, Internet- Gateway, Squid / Dansguardian, VPN / OpenVPN to access internal company resources from outside.
Setting up and working with SIM Bank Elgato, Elgato GSM-gateways and GSM-sluices GoIPx. Setting up and maintenance of computer systems and client workstations. Setting up and maintenance of small local networks.