Even if you aren't aware it's running, it may be running in the background. A good rule of thumb, if you want to share files with others at all, is to shut down file sharing when you're not actively downloading or permitting others to download from you. That sounds far easier than it really is, however. Each P2P application has different ways of turning off file sharing. And these may change from one version to the next of the same application.
In addition, P2P applications can be a huge drain on bandwidth and system resources and can expose the system/computer owner to legal liability for illegal content (such as child pornography) or pirated content housed on the servers or computer. Many experts believe that they provide the potential for amassing large networks of computers for cyberterrorism and cybercriminal purposes. They cite several cooperative networking projects, such as the one to find life in outer space operated by SETI and another to break encryption codes, as proof that this kind of networking is possible and easy to create.
You have the right to know what's being installed on your computers and networks. You should start by setting rules about what can and can't be used and how permission can be obtained for installing new software applications. Rules also should be set for running all programs and files through an automatically updated virus blocker before they're installed on your computer, and parents should make sure that no software is installed without their permission. But with P2P and IM programs, you may need protective software more than ever. These should include an adware blocker or removal program, a firewall, and an anti-virus program.
Often consumers (and even some network administrators) don't understand which security applications and hardware they really need and frequently confuse one with the other. An anti-virus product will review files that you intentionally download or install. A firewall will keep out intruders and attempts to install something without your knowledge. They work hand in hand, like good brakes and seat belts. You aren't fully protected unless you use both. Firewalls can be either software or hardware, although a hardware firewall provides much better and comprehensive protection. They're also often included in wireless routers and in cable routers, for broadband users. So, check to see what you already have before you spend money to buy something you don't need.
But unfortunately, having the software and making sure you use it correctly are very different, though. Using the wrong settings, or disabling these protections because they take too long to load, can leave you wide open to malicious code and hacking attacks. Read the directions that come with your products carefully, and ask the company's help desk or seek understandable information from their site if you have questions. If all else fails, ask your eight-year-old for help. They're the cheapest computer experts I know that still do house calls.
Parry Aftab is a cyberspace lawyer, specializing in online privacy and security law, and also is executive director of WiredSafety. She hosts the Web site aftab.com and blogs regularly at theprivacylawyer.blogspot.com.