You might need to obtain some security software: anti-virus, firewall, and file encryption programs.

Use Anti-Virus Programs

Anti-virus programs look at the contents of each file, searching for specific patterns that match a profile - called a virus signature - of something known to be harmful. For each file that matches a signature, the anti-virus program typically provides several options on how to respond, such as removing the offending patterns or destroying the file.

When the anti-virus program vendors learn about a new virus, they provide an updated set of virus signatures that include that new one. Through features provided by the updated anti-virus program, your home computer also automatically learns of this new virus and begins checking each file for it, along with checking for all the older viruses. However, viruses never completely fade away. Their signatures remain part of the master version of all virus signatures.

Use a Firewall Program

On a computer, this security software acts much like a guard when it looks at network traffic destined for or received from another computer. The firewall determines if that traffic should continue on to its destination or be stopped. The firewall “guard” is important because it keeps the unwanted out and permits only appropriate traffic to enter and leave the computer.

To do this job, the firewall has to look at every piece of information – every packet – that tries to enter or leave a computer. Each packet is labeled with where it came from and where it wants to go. Some packets are allowed to go anywhere while others can only go to specific places. If the firewall allows the packet to proceed (being acceptable according to the rules), it moves the packet on its way to the destination. In most cases, the firewall records where the packet came from, where it’s going, and when it was seen.

The firewall can check whether a given packet should pass, allowing the computer’s user to respond to unanticipated network traffic. Finally, firewalls can filter packets based not only on their point of origin or destination, but also on their content.

With a firewall, you can control which packets are allowed to enter your home computer and which are allowed to leave.

Use a File Encryption Program and Access Controls

Think to your home computer security. The problem is to control access to files and folders. The access control device here is the access control list or ACL. ACLs define who can perform actions on a file or folder: reading and writing, for example. ACLs are equivalent to a locked filing cabinet for paper documents.

Different computer systems provide different types of ACLs. Some have fine-grained controls while others have virtually none. The key is to use all the controls that are available on your computer.

	Internet Security Knowledge
	1. Why is the computer security important? 2. The Incidents of Network Security 3. Why is the home computer a popular target for hackers? 4. The methods to ensure Internet security 5. What Security Software I Should Use? 6. What is firewall software? 7. The keys for firewall protection 8. What is Intrusion Detection? 9. Be careful when reading email with attachments 10. The basic Internet-based technologies.

On a computer, when access to information can’t be limited, such for an e-commerce transaction over the Internet, that information is concealed through a mathematical process called encryption with another security software - Encryption Program. Encryption transforms information from one form (readable text) to another (encrypted text). Its intent is to hide information from those who have neither the transformation method nor the particulars (the decryption keys) to transform the encrypted text into readable text. The encrypted text appears to be gibberish and remains so for people who don’t have the scheme and the keys.

Computer-based encryption schemes must also withstand the test of time. For example, if a credit card encryption scheme needs six months of computer time to break, the resulting clear text credit card number is probably still valid and, therefore, useful to an intruder. In this case, the encryption scheme isn’t strong enough to guard the information for its entire useful lifetime.

So, to guard paper or computer files, you need to limit who has access to them by using the access control devices, whether filing cabinets and safes for paper or access control lists for information on a computer system. For assets whose access cannot be sufficiently limited, you need to encrypt them strongly enough so that the time it takes to decrypt them is longer than their useful life.