Firewalls
In order to access resources globally from a computer or private network, it is important to connect to the internet.A computer that has internet connection shares and receives data globally. the sharing and receiving of data globally calls for computer users concern. An unauthorized user could access information via the internet and obtain information illegally.
The use of firewalls prevents an unauthorized person on the internet from breaking into a particular network and retrieving information from it. it also helps a network in monitoring information that goes out or comes in through a particular network.
Several types of firewall techniques are used in modern day computers
these are
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Packet filter: Looks at each packet entering or leaving the network and accepts or rejects it based on user-defined rules. Packet filtering is fairly effective and transparent to users, but it is difficult to configure. In addition, it is susceptible to IP spoofing. |
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Application gateway: Applies security mechanisms to specific applications, such as FTP and Telnet servers. This is very effective, but can impose a performance degradation. |
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Circuit-level gateway: Applies security mechanisms when a TCP or UDP connection is established. Once the connection has been made, packets can flow between the hosts without further checking. |
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Proxy server: Intercepts all messages entering and leaving the network. The proxy server effectively hides the true network addresses. |
Many firewalls uses two or more of the technique combined together to give a strong firewall support.
For more information on firewalls, visit...... http://www.cerias.purdue.edu/about/history/coast_resources/firewalls/