In the computer industry, Internet security refers to techniques for ensuring that data stored in a computer can't be read or compromised by any individuals without authorization. Most security measures involve data encryption and passwords. Data encryption is the translation of data into a form that is unintelligible without a deciphering mechanism. A password is a secret word or phrase that gives a user access to a specific program or system.

Internet security professionals should be fluent in the four major aspects:

Penetration testing

Intrusion Detection

Incidence Response

Legal / Audit Compliance

Routers

For more details on this topic, see Router.

Network Address Translation (NAT) typically has the effect of preventing connections from being established inbound into a computer, whilst permitting connections out. For a small home network, software NAT can be used on the computer with the Internet connection, providing similar behaviour to a router and similar levels of security, but for a lower cost and lower complexity.

Firewalls

For more details on this topic, see Firewall.

A firewall blocks all "roads and cars" through authorized ports on your computer,thereforerestricting unfettered access. A stateful firewall is a more secure form of firewall, and system administrators often unite a proxy firewall with a packet-filtering firewall to create a highly secure system. Most home users use a software firewall. These types of firewalls can create a log file where it records all the connection details (including connection attempts) with the PC.

Anti-virus

For more details on this topic, see Malware.

Some people or companies with malicious intentions write programs like computer viruses, worms, trojan horses and spyware. These programs are all characterised as being unwanted software that install themselves on your computer through deception.

Trojan horses are simply programs that conceal their true purpose or include a hidden functionality that a user would not want.

Worms are characterised by having the ability to replicate themselves and viruses are similar except that they achieve this by adding their code onto third party software. Once a virus or worm has infected a computer, it would typically infect other programs (in the case of viruses) and other computers.

Viruses also slow down system performance and cause strange system behavior and in many cases do serious harm to computers, either as deliberate, malicious damage or as unintentional side effects.

In order to prevent damage by viruses and worms, users typically install antivirus software, which runs in the background on the computer, detecting any suspicious software and preventing it from running.

Some malware that can be classified as trojans with a limited payload are not detected by most antivirus software and may require the use of other software designed to detect other classes of malware, including spyware.

Anti-spyware

For more details on this topic, see Malware.

There are several kinds of threats:

Spyware is software that runs on a computer without the explicit permission of its user. It often gathers private information from a user's computer and sends this data over the Internet back to the software manufacturer.

Adware is software that runs on a computer without the owner's consent, much like spyware. However, instead of taking information, it typically runs in the background and displays random or targeted pop-up advertisements. In many cases, this slows the computer down and may also cause software conflicts.

Browser choice

Internet Explorer is currently the most widely used web browser in the world, making it the prime target for phishing and many other possible attacks.