Written By: Chris Brown
Last Revised: 04/05/2007
Computer surveillance is the act of observing a person by accessing their computer or remotely monitoring their actions on their computer.
When you look at how much computers have become a part of our daily lives, itís no surprise that computers have become a means of tracking people. Over the years, with the development of new technologies, computer surveillance methods have changed and with them prevention methods have been developed.
A hardware type keylogger 
Key loggers are simply devices which record all keystrokes from a keyboard. This can provide the surveyor with passwords, credit card numbers, documents, e-mails, and other sensitive information. Key loggers come in two main forms; software and hardware. The different types of hardware key loggers can either be soldered onto the keyboard or attached to the cable of the keyboard which plugs into the computer. Software key loggers are much more common, as they can be installed through viruses and other types of malware. They will often send the information they gather back to the surveyor via the internet through e-mail or posts the information to a website to be retrieved later.
A packet sniffer is a computer program which uses the computersí network interface to take in all packets on a network that it can, more importantly, those that are not meant for that computer. These packets can then be used to analyze a usersí traffic over the network which can reveal; websites visited, e-mails, file transfers, etc. Packet sniffers today are easy to come by and are undetectable since they simply run passively as a receiver on a network. One of the most famous examples of a packet sniffer is the FBIís Carnivore system which would be installed physically on a network or at an ISP hub and would look at all packets running through the system and filtering out those it was interested in.
Spyware is a computer program which collects information about a user without their informed consent  by analyzing their internet usage as well as scanning files on the infected computer. The information collected can be; records of internet usage, credit card numbers, e-mail addresses, etc. This information can be used for a range of purposes, from malicious attacks on the user to selling the information to advertising companies.
Spy software, not to be confused with spyware, is installed intentionally by the owner of the computer, most commonly to legally monitor the internet activity of an employee, child, or spouse. The program will commonly run in the background, hidden from the user and can show the controller a display of the logged internet activity for review at a later date.
There are several different methods of protecting yourself against unwanted computer surveillance, some that are more practical than others.
A firewall cannot directly prevent computer surveillance; however it can help prevent sensitive information from being sent out from your computer. All programs which record information must have a way for the attacker to obtain the data. This can generally be done through internet communications or for the attacker to physically retrieve the data from the computer. A firewall can prevent a program which is suspicious or not trusted from accessing the internet without your permission. A firewall can also help to prevent malicious users from accessing your system remotely and installing spyware, key loggers, and other such programs.
Installing antivirus software can greatly increase your protection from malicious software. Antivirus software can help prevent the installation of malicious software as well as having a good chance to detect and remove malicious software that has already been installed on the system.
Protection from people packet sniffing is a little more difficult since to be fully protected you would need to stop your information from reaching an attacker. Encryption is your best practical method when it comes to securing your wireless communications. Through use of wireless encryption protocols, such as WPA2, you can provide a good level of protection for your wireless communication. Methods of blocking your information from reaching other users are available from faraday cages to simple paint which can block wi-fi signals from reaching beyond itsí boundaries, but are often much harder to implement than they are worth.
Even securing your system with these methods is useless if an attacker can gain physical access to your system. This can allow for physical key loggers to be installed on a system as well as permitting the attacker to copy files if there is prolonged exposure to the machine.