The term VPN has been
associated in the past with such remote connectivity services
as the public telephone network and Frame Relay PVCs, but has
finally settled in as being synonymous with IP-based data
networking. Before this concept surfaced, large corporations
had expended considerable resources to set up complex private
networks, now commonly called Intranets. These networks were
installed using costly leased line services, Frame Relay, and
ATM to incorporate remote users. For the smaller sites and
mobile workers on the remote end, companies supplemented their
networks with remote access servers or ISDN. At the same time,
the small- to medium-sized enterprises (SMEs), who could not
afford dedicated leased lines, were relegated to low-speed
switched services.
If you have been using the
Internet for any length of time, and especially if you work at
a larger company and browse the Web while you are at work, you
have probably heard the term firewall used. For example, you
often hear people in companies say things like, "I can't use
that site because they won't let it through the
firewall."
Every day, the citizens of the
Internet send each other billions of e-mail messages. If you
are online a lot, you yourself may send a dozen or more
e-mails each day without even thinking about it. Obviously,
e-mail has become an extremely popular communication tool.
Have you ever wondered how e-mail gets from your desktop to a
friend halfway around the world? What is a POP3 server, and
how does it hold your mail? The answers may surprise
you, because it turns out that e-mail is an incredibly
simple system at its core! In this article, we'll take an
in-depth look at e-mail and how it works!
Intrusion detection
systems (IDSs) are software or hardware systems that automate
the process of monitoring the events occurring in a computer
system or network, analyzing them for signs of security
problems. As network attacks have increased in number and
severity over the past few years, intrusion detection systems
have become a necessary addition to the security
infrastructure of most organizations. This guidance document
is intended as a primer in intrusion detection, developed for
those who need to understand what security goals intrusion
detection mechanisms serve, how to select and configure
intrusion detection systems for their specific system and
network environments, how to manage the output of intrusion
detection systems, and how to integrate intrusion detection
functions with the rest of the organizational security
infrastructure. References to other information sources are
also provided for the reader who requires specialized or more
detailed advice on specific intrusion detection
issues.
Computer viruses are mysterious
and grab our attention. On the one hand, viruses show us how
vulnerable we are. A properly engineered virus can have an
amazing effect on the worldwide Internet. On the other hand,
they show how sophisticated and interconnected human beings
have become. For example, MSBlaster worm and the SoBig virus.
The Melissa virus - which became a global phenomenon in March
1999 -- was so powerful that it forced Microsoft and
a number of other very large companies to completely turn
off their e-mail systems until the virus could be
contained.