Especially linux and network administration, also bsd, unix, windows at a pinch and exotic oddities like clusters of mac minis, telephone exchanges, nuclear power station control centres, even printers. In addition development in any language especially C, lisp, scheme, perl, shell (bash), python. JavaScript if necessary. Particular penchant for holistic site reliability and security; translating between developers, managers and the wider business; pulling unexpected tricks out of my sleeve in emergencies; actually documenting things.