As an employer, you're well within your rights to monitor network traffic and disk contents, but savvy employees may use encryption to hide their correspondence from your eyes. They have to read and write in English, however, so a program that monitors keystrokes or takes continual snapshots of the screen defeats even the most robust security. That's what eBlaster and its sibling product, Spector, do. Back Orifice does all this. You can still download Back Orifice for free, but some people are scared to go anywhere near the controversial, hacker-oriented product.
Many people feel that paying money for a product confers an aura of legitimacy on it.
Also, many antivirus programs routinely scan for an active BO server, rendering it less effective and harder to hide on a target machine. The leader in the keystroke monitoring market is WinWhatWhere Investigator, but eBlaster is different in several respects. Most notably, you can give it a list of words and phrases to look out for. This NSA-like feature may actually be a legal protection for an employer, because it indicates your intent to monitor only sensitive, illegal or damaging information transfer, not personal information. If you suspect that you're the target of snooping, whether it may be justified or not, the most effective way to block it is with a personal firewall product that monitors outgoing traffic, such as ZoneAlarm .