Analytics supports regular expressions so you can create more flexible definitions for things like view filters, goals, segments, audiences, content groups, and channel groupings. In the context of Analytics, regular expressions are specific sequences of characters that broadly or narrowly match patterns in your Analytics data.
Find very useful cheat sheet of IPv6 – the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet.
Tcpdump is a common packet analyzer that runs under the command line. It allows the user to display TCP/IP and other packets being transmitted or received over a network to which the computer is attached. Distributed under the BSD license, tcpdump is free software.
Find a very useful cheat sheet of well-known Internet Protocol Security (IPsec) – a protocol suite for secure Internet Protocol (IP) communications that works by authenticating and encrypting each IP packet of a communication session.
Useful CLI reference card by Jens Roesen – find the most common checkpoint commands.