Network firewall

From Computing and Software Wiki

Network Firewall is now considered as a first line of defense in the form of a barrier against outside attacks, which is installed on computers connect to internet. In general Firewall prevents the dangers of Internet from spreading to your internal network. It more like a moat of a medieval castle that a firewall in a modern building. It serves multiple purposes [1:21]:

• It restricts people to entering at a carefully controlled point.
• It prevents attackers from getting close to your other defenses.
• It restricts people to leaving at a carefully controlled point.[1:21]

In practice,a firewall is a collection of hosts, routers, and other hardware that designed to prevent unauthorized electronic access between two parts of a network. It is also a device or set of devices configured to permit, deny, encrypt, decrypt, or proxy all computer traffic between different security domains based upon a set of rules and other criteria.[3]

Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.[3]

Contents 1 Why Firewall 1.1 What is Firewall 1.2 Benefits of Firewall 1.3 Limitations of Firewall 2 Firewall Types 2.1 Simple packet filtering: IP or filtering Firewall 2.2 Application Firewalls: proxy servers 2.3 Stateful multilayer-inspection Firewalls 3 Firewall Architectures 3.1 Single-Box 3.2 Screened host 3.3 Screened subnet 4 Firewall Software 5 References 6 See also 7 External links 8 Time-stamped Signature

Why Firewall

The Internet is marvelous technological advance that provides access to information, and the ability to publish information, in revolutionary ways. But it's also a major danger that provides the ability to pollute and destroy information in revolutionary ways. For this reason, no matter what kind of information you put on Internet, you may always try to protect:

• Your Data?
  • Secrecy: accessibility for a certain group of people
  • Integrity: no data change by others
  • Availability: always able to use it by you or by a group of people who have the permit.
• Your Resources? Your computer cycle and storage space.
• Your Reputation? No one should appear on the Internet with your identity. [1:7]

if you answer YES to any of above, then Network Firewall is the solution you needed.

What is Firewall

As figure 1 shows, a Firewall is a box/device between two connected networks, it has the following definitions:

• A Firewall is an integrated collection of security measures designed to prevent unauthorized electronic access to a networked computer system.[3]
• A Firewall is a device or set of devices configured to permit, deny, encrypt, decrypt, or proxy all computer traffic between different security domains based upon a set of rules and other criteria.[3]
• A Firewall is a device that divide a network into parts, when some parts have distinct security needs.[1:23]
• A Firewall is a separator, a restricter, an analyzer.[1:22]

Benefits of Firewall

Limitations of Firewall

Firewall Types

Simple packet filtering: IP or filtering Firewall

Application Firewalls: proxy servers

Stateful multilayer-inspection Firewalls

Firewall Architectures

Single-Box

Screened host

Screened subnet

Firewall Software

References

1. Elizabeth D. Zwicky, Simon Cooper, and D. Brent Chapman;Building internet Firewalls, Second Edition; Published by O'Reilly & Associates, Inc. @2000; ISBN:1-56592-871-7, McMaster Thode Library: TK 5105.59.Z85 2000
2. John R. Vacca, Scott R. Ellis; Firewalls, Jumpstart for Network and Systems Administrators; Elsevier digital press @2005; ISBN: 1-55558-297-4, McMaster Thode Library: TK 5105.59.V32 2005
3. Firewall, Wikipedia, Accessed on April 3rd 2009 21:35.

See also

External links

1. Firewalls and Internet Security by Frederic Avolio, Avolio Consulting, Cisco Systems.
2. History of Firewall Technologies A text file by Rik Farrow and Richard Power, Spirit.com

Time-stamped Signature

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