As the Internet grows, so will this underlying base of unlawful users. Policing the Internet is not a viable option due to its massive complexity, so it is up to individual users to take action themselves. The Internet is a hostile environment, and should be treated as such. A dedicated hardware firewall solution would the best choice, but this type of technology often requires a complex understanding of network theory. The cost is also a major objection, as hardware firewalls can run to thousands of dollars.
Personal firewalls attempt to protect PCs from various malicious network activities.
DoS attacks exploit vulnerabilities in software to cause the victim's system to either stall or crash. Another popular attack is a Trojan horse, which acts as backdoor, thus allowing an intruder complete access to your system's resources. Most Trojans are housed within unsolicited e-mail messages and should be regarded as viruses. Each computer on a network must have some kind of identification for data to be directed to and from systems. The IP address identifies each computer within a network, even the Internet.