A system designed to prevent unauthorized access to or from a private network. 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.
A firewall is considered a first line of defence in protecting private information.
Electronic junk mail or junk newsgroup postings. Some people define spam even more generally as any unsolicited e-mail. Real spam is generally e-mail advertising for some product sent to a mailing list or newsgroup.
In addition to wasting people's time with unwanted e-mail, spam also eats up a lot of network bandwidth. Consequently, there are many organizations, as well as individuals, who have taken it upon themselves to fight spam with a variety of techniques. But because the Internet is public, there is really little that can be done to prevent spam, just as it is impossible to prevent junk mail.
Spyware is any software which employs a user's Internet connection in the background without their knowledge or explicit permission.
Silent background use of an Internet connection must be proceeded by a complete and truthful disclosure of proposed back channel usage, followed by the receipt of explicit, informed, consent for such use.
Any software communicating across the Internet without these elements is guilty of information theft and is properly known as Spyware.
A program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. Viruses can also replicate themselves. All computer viruses are manmade. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.
It is recommended that all users run up-to-date anti-virus software at all times. As a guide, updates to most anti-virus programs are released weekly.
A computer worm is a self-replicating computer program, similar to a computer virus. A virus attaches itself to, and becomes part of, another executable program; a worm is self-contained and does not need to be part of another program to propagate itself.