How Does Network Security Work?

Instructor: David Whitsett

David has taught computer applications, computer fundamentals, computer networking, and marketing at the college level. He has a MBA in marketing.

This lesson will define network security and explain a little about how it works. We will also discuss the kinds of threats that networks face and what's at risk if the security fails.


The term network security refers to protecting your digital assets (computer systems, programs, and information) from intrusion, destruction, theft, modification, or misuse. Network security can be made up of hardware devices, specialized software, physical security (i.e. locked computer rooms), and rules for people to follow. Just like securing your home, a network security system must protect against threats coming in from the outside and also deal with intruders if they make it inside. Criminals who access data or networks illegally are known as hackers.

Many people lock the doors and windows of their homes to prevent people from coming in who don't belong there. Intruders can cause problems, including theft, vandalism, and harm to your family. People also close their blinds or drapes to prevent a 'peeping Tom' from looking inside. Some people have additional security measures in place, such as alarm systems to detect a break-in or a fire, dogs to bark and/or protect the family, safes to keep valuables in, or even weapons to protect themselves as a last resort. Think of these measures as additional layers of security on top of the basic locks on the outside.

Just as with home security, there can be multiple layers to an effective network security system. Often the first layer is authentication, which means requiring a password to access a network resource. A password is like your house key or alarm code; you only give it to someone you trust. Networks can also have intrusion detection systems which alert network administrators to a breach and detect unusual activities within the network. These systems are similar to motion detectors or window/door sensors in an alarm system, as they let you know when someone unauthorized has gotten inside. A network firewall can enforce rules within the network to control who can or can't use certain resources, sort of like child-proof locks you have within your home to keep your kids away from pesticides and harmful chemicals. Anti-virus software can prevent malicious software coming in from the outside from damaging network data or watching network activities--networks can have peeping Toms too! Wireless networks must be protected from outside eavesdropping by requiring security keys (passwords) for access and by encrypting (scrambling) network transmissions.

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