Terminology
A
hacker
is someone who masters the inner
workings of operating systems and utilities in an
effort to better understand them
A
cracker
is someone who uses his or her
knowledge of operating systems and utilities to
intentionally damage or destroy data or systems
In general,
root
refers to a highly privileged user ID
that has all rights to create, delete, modify, move,
read, write, or execute files on a system
A
firewall
is a specialized device that selectively
filters or blocks traffic between networks