User guide

User Guide 1
1 Introduction to Network
Security
About networks and network security
A network is a group of computers and other devices that are connected to each other. It can be two
computers that you connect with a serial cable, or many computers around the world connected through the
Internet. Computers on the same network can work together and share data.
Although the Internet gives you access to a large quantity of information and business opportunity, it also
opens your network to attackers. A good network security policy helps you find and prevent attacks to your
computer or network.
Attacks are costly. Computers may need to be repaired or replaced. Employee time and resources are used to
fix problems created by attacks. Valuable information can be taken from the network.
Many people think that their computer holds no important information. They do not think that their computer
is a target for a hacker. This is not correct. A hacker can use your computer as a platform to attack other
computers or networks or use your account information to send email spam or attacks. Your personal
information and account information is also vulnerable and valuable to hackers.
About Internet Connections
ISPs (Internet service providers) are companies that give access to the Internet through network connections.
Bandwidth is the rate at which a network connection can send data: for example, 3 megabits per second
(Mbps).
A high-speed Internet connection, such as a cable modem or a DSL (Digital Subscriber Line), is known as a
broadband connection. Broadband connections are much faster than dial-up connections. The bandwidth of
a dial-up connection is less than.1 Mbps, while a cable modem can be 5 Mbps or more.
Typical speeds for cable modems are usually lower than the maximum speeds, because each computer in a
neighborhood is a member of a LAN. Each computer in that LAN uses some of the bandwidth. Because of this
shared-medium system, cable modem connections can become slow when more users are on the network.
DSL connections supply constant bandwidth, but they are usually slower than cable modem connections.
Also, the bandwidth is only constant between your home or office and the DSL central office. The DSL central
office cannot guarantee a constant connection bandwidth to a web site or network.