A computer firewall is similar to what firefighters use when fighting forest fires. It is a protective barrier created to stop destructive forces. A firewall prevents spam, viruses, and other unwanted data from invading a network and destroying files or allowing someone to download personal information. Network administrators can also set the firewall to prevent network users from accessing Web pages and certain servers outside the network. Computer firewalls can be implemented in both hardware and software, or a combination of both. The CTC network uses the Cisco Systems Secure PIX 525 Firewall. PIX is short for Private Internet Exchange firewall.
Software firewalls are customizable programs that filter information before it enters a network. A firewall will flag outbound packets so when your computer establishes a connection with another computer to exchange information, the firewall will know that the incoming information has permission to enter the network. If the firewall does not recognize the source IP address on a packet that is entering the network as one from its private network then it will not let the packet enter the network. A firewall uses three methods to examine packets:
Packet filtering – Filters created by the network administrators analyze each data packet to determine if they have been requested by someone in the system. The network administrators can customize the firewall to filter information based on different criteria.
Proxy service – The firewall stores often-requested sites, for example www.msn.com, from the Internet and then sends it to the requesting computer.
- Stateful inspection – A database examines certain key parts of a packet and compares it with information stored on the database.
The firewall protects users and the network from:
- Remote login
- Application backdoors
- Viruses
- Spam
- Email bombs
- Viruses
- Denial of service
For more information contact the Help Desk at extension 3103.
Send mail to help.desk@ctcd.edu with questions or comments about this web site.
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Telephone (254)501-3103
FAX (254)526-1950
P.O. Box 1800, Killeen, TX 76540-1800