Tip #3940 - Firewall Basics
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Firewall
Basics
We here at WorldStart
have talked about firewalls before, but we have never just taken a step
back and given you the basics about them. So, that's exactly what I'm
going to do for you today!
A firewall is designed
to help protect your computer from being attacked by malicious users or
by malicious software programs, such as viruses that use unsolicited incoming
network traffic and so on. Now, before you disable your firewall, you
must disconnect your computer from all the networks, including the Internet.
Now, basically, a
firewall is a system that is designed to prevent unauthorized access to
or from a private network. You can implement firewalls in your hardware,
software or both. Firewalls are frequently used to prevent unauthorized
Internet users from accessing private networks that are connected to the
Internet. With all that said, let's talk about some of the different types
of firewalls available.
Different
Types of Firewalls
Different firewalls
use different techniques. Most firewalls use two or more of the following
techniques:
Packet Filters:
A packet filter looks at each packet that enters or leaves the
network and accepts or rejects the packet based on user-defined rules.
Packet filtering is fairly effective and transparent, but it is difficult
to configure. In addition, it is susceptible to IP spoofing.
Application
Gateway: An application gateway applies security mechanisms to
specific programs, such as FTP and Telnet. This technique is very effective,
but it can cause performance degradation.
Circuit-layer
Gateway: This technique applies security mechanisms when a Transmission
Control Protocol (TCP) or User Datagram Protocol (UDP) connection is established.
After the connection has been established, packets can flow between the
hosts without any further checking.
Proxy Server:
A proxy server intercepts all messages that enter and leave the
network. The proxy server effectively hides the true network addresses.
Application
Proxies: Application proxies have access to the whole range of
information in the network stack. This permits the proxies to make decisions
based on basic authorization (the source, the destination and the protocol)
and also to filter offensive or disallowed commands in the data stream.
Application proxies are "stateful," meaning they keep the "state"
of connections inherently. The Internet Connection Firewall feature that
is included in Windows XP is a "stateful" firewall, as well
as, the Windows Firewall. The Windows Firewall is included with Windows
XP Service Pack 2 (SP2).
Now that you know
some of the different types of firewalls and their configurations, you
can better determine which one will work the best for your computer. I
hope you find this information helpful!
~ Ramachandran Kumaraswami
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