Protecting Your Home Computer And The Perimeters Computer Science Essay

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The third level in the defense-in-depth security strategy is defending the perimeter of the network.

Your network perimeter is the point where your home computer network meets untrusted networks. Many people assume that this means only the connection between their internal network and the Internet. From a defense-in-depth perspective, this definition is too narrow.

A network's perimeter is the area of the network that is most vulnerable to attack from the outside. The network perimeter includes every point where your internal network is connected to external networks. This can include connections to:

The Internet [1] .

Your business or employment.

Home business partners [2] .

Remote users to your network [3] .

Wireless networks [4] .

Internet applications [5] .

Examples of devices used in the network perimeter include:

Routers [6] .

Mail and Web servers [7] .

Software and hardware firewalls [8] .

Why is it important to defend the perimeter of your home computer network?

Figure 1

Figure - Defense-in-Depth Level 3 - Protecting Perimeter Defenses

It is important that you consider security for the network as a whole, including all access points to your network and not just for individual areas

The most logical thing to do is to focus your security efforts on the area from which you are most likely to get an attack… the Internet. However, hackers may also attempt to attack your network through any other access point. It is critical that all network entrances and exits [9] are secure.

If you are running a home-based business, you will not be responsible for the security implementation of your business partners. You cannot trust all access from that environment. You would also not have control of remote users' [10] hardware, so you cannot trust access from that environment either.

You would most likely have a connection between your business computer network and home computer network. Attackers can use these connections to their advantage. For example, suppose you operate an offline business [11] at external premises. If your business network's security system is secured but your home network is not secured, hackers can use your home network to access your business computer network. If your home network is connected to your business network, you need to use a secure VPN connection [12] .

Some hackers do not directly attack your network perimeter [13] â€¦ they use e-mails linked to false websites. For example, in a phishing [14] attack, the attacker broadcasts an email [15] which appears to come from a legitimate business e.g. your online bank. Phishing attacks attempt to trick the recipient (you?) into providing them with you're your / their? sensitive bank account information. A link [16] is provided in the e-mail which takes you to a fake website [17] . When you type in your details into the fake website they are captured by the phisher [18] . Phishing scams damages both the financial well being of the victim and the business reputation of the legitimate business.

It is important that you consider security for the network as a whole, including all access points to your network and not just for individual areas

How can you protect the perimeter of your home computer network?

There are several ways that you could secure your personal computer.

One way is through the installation of a firewall.

The firewall is like a building security guard. A security guard's responsibility is to make sure that the building is secured and to police who comes in and out of it. He has the right to stop anyone he suspects does not meet the building administrator's rules of entry. He is entitled to ask a person who is entering who they are, where they are going and the purpose of their visit. If you try to enter the building and you are not authorised, the security guard will ask you to leave! If you don't, he can have you evicted!

A computer firewall [19] is a security guard who protects your computer from outside threats. You define the rules or the conditions of entry for the firewall. The firewall secures the network and polices the rules. The firewall will block anything coming from the Internet or sent to the Internet that does not meet these rules.

A firewall also has a very detailed recording system. It will identify the source of the data packets [20] , their destination and timestamp. These records allow the firewall to recognize the same data packet in the future and provide passage for it. Firewalls are a very useful tool and must be installed.

What are the types of firewalls?

There are three main types of firewalls…hardware [21] , software [22] and wireless [23] . If you have a home computer network, then you would need to install both hardware and software firewalls! If you're using a wireless network, then you would need to install a wireless router [24] and software firewall.

Hardware Firewalls

The hardware firewall is a separate piece of equipment like a router or modem [25] . If you have a broadband connection [26] and you received a modem, the firewall is pre-installed. If your modem does not have a pre-installed firewall [27] , then you will need to purchase a separate piece of hardware called a router [28] . This sits between your modem and the computer network.

Veronica's firewall was installed using a CD and the web browser. Her Internet Service Provider (ISP) [29] had provided her with an installation CD. During the installation process, the software [30] asks questions about Internet security which she answered. Once the installation was completed, Tommy reviewed the settings in the web browser and made some changes. You can also do that by logging into the website the ISP give you.

If you are planning to protect a small network of computers, say in your home or at a small office, a hardware router is ideal for you. Hardware routers are more convenient to use for multiple computers. They usually have at least four network ports [31] to connect four computers.

However, be prepared for the amount of wiring you will have to set up for the network to operate. It will clutter your workspace.

Wireless Firewalls

If you want a wireless network of computers [32] , you would definitely need it to be protected by a wireless router [33] .

Some advantages of using a wireless router include

No wiring will be required, so it avoids clutter. It can connect personal computers, printers, scanners, without the use of any physical wiring;

It is ideal if you want to protect a set of laptops, notebook computers, and desktop computers

Some of the disadvantages of using a wireless router include:

The radio signals that wireless devices use (including wireless routers) can be intercepted by other individuals with the right equipment;

Wireless routers are not always equipped with a built-in firewall, so you might have to purchase a firewall separately; and

You might have to purchase extra equipment to set up a wireless router.

Software Firewalls

Since Veronica has just one computer, she can get away with just having a software firewall. However, she would find that her computer would operate very slowly because it now has a very heavy workload. It is much better for her install both types of firewalls i.e. hardware & software, even if she has only one computer.

Some systems like Windows XP Professional & Vista [34] have a software firewall which is pre-installed. Software firewalls can also be purchased as part of Internet security suites e.g. Norton's Internet Security 2010 [35] .

Some of the advantages of a software firewall include:

No additional hardware is required for it to work; and

There is no additional wiring that needs to be installed for the software to work.

However, there are also some disadvantages to deciding on using a software firewall:

A software firewall can be a bit costly;

You will need to install and configure the software to get it to work properly; and

If you have multiple computers, you will need to install the software on each one of them to get them protected.

What you need to know before you install a firewall:

Installation of firewalls is straightforward. However, you might need to know a few things before installing a firewall.

1. Firewalls can block file and printer sharing. If you had set up your computers to share files with others in your house, installing a firewall on any computer can suspend that feature. You need to select the option that allows you to continue with file and printer sharing.

2. Firewalls can temporarily take you off the Internet. This usually happens if you connect to the Internet using a home computer network via a router. Several routers have difficulty sharing Internet access to individual computers in the network. While this is solved by power cycling [36] , some routers are simply not compatible with some firewalls. If you have these problems, then call the firewall supplier for assistance. [37] 

3. Firewalls can block you from entering a secure network. If you work from home and need access to your office network using a secure channel [38] , you have to coordinate with your office IT department before installing a firewall. The firewall may cut you off entirely because it can put another layer of security to an already secured connection. Find out which firewall works best with your company security protocols [39] .

Why it is Important to Configure Your Firewall Software

In our story, Veronica wanted to know if her system would be completely safe from online attack once she installed the most up-to-date computer security system available. . The answer is yes… but her system must be configured [40] correctly!

Here is an example of a recent attack on another client's home computer network:

Jim's network has a computer with a state-of-the-art security system. It includes:

A hardware router…hardware and software firewall;

Up-to-date anti-virus and anti-spyware protection;

Anti-phishing and identity protection controls;

Backup systems and system diagnostics; and

Strong password security.

Yet despite this comprehensive security system, Jim's network was recently hacked… and it happened like this:

Several months ago, Jim's wife Marcia, was completing an assignment for her course of study. As she worked, she noticed the computer starting to make a "busy" noise… the hard drive sounded like it was working very hard! This noise went on for about half an hour. What made it really strange was that she was only doing typing at the time. She had the e-mail and word processing package open but did not have the web browser open! There were no scans operating in the background. However, her computer is always logged onto the Internet using a broadband connection.

Marcia's computer began to operate very slowly and the mouse operated unpredictably. This was very frustrating for her because she needed to complete her assignment that day. She decided to stop work until the system settled down.

When Jim arrived home his task was to investigate the problem and fix it, ASAP! Marcia also told Jim that some spam had arrived in the spam filter but she did not touch it. She also saw a message appear that some viruses and spyware had entered but she did not know what to do, so she left it.

Jim's immediate reaction was that the computer had been hacked. This means that some unknown person had found a weakness in their computer's firewall and gained unauthorized access to their network. Unfortunately, the software in the hardware firewall did not detect and automatically block the hacker's intrusion. Jim's question was, how did this happen?

The Investigation

Jim checked the logs [41] in the hardware firewall. It showed him that there weren't any recent attacks… which surprised him.

He then checked the activity logs [42] of the Internet security system for details of any hacking attacks [43] â€¦ but again there weren't any! The log showed Jim that Code Red and Nimda worms [44] were detected but not automatically blocked.

Jim used an independent website to check how well the firewall was working. It was here that he found out why the firewall failed to detect and block the hacker's intrusion.

The test found that Jim's computer network's firewall had a port configured "open" when it should have been "closed". A port is like a door in a building. Jim had locked every port (door) in the computer except that one!

This particular port would be used if Jim was using his home computer network to publish a website on the World Wide Web. Most people publish their websites through an Internet service provider (ISP) [45] , but some use their own computers. If Jim was not publishing his website on his network, then he should always have kept that port closed.

Jim also found another problem. The anti-virus software did not automatically block hacker attacks. Rather, it displayed a message on the screen and asked the user to take action. It should have been configured to automatically fix any problem that may occur. Think about it….It is 2 a.m. Jim wouldn't want to be getting out of bed to fix his computer!

The hacker would not have had any joy on Jim's network. There is no personal information that is easy to find. All Jims' Jim's personal data, logins and passwords are locked away in an identity safe [46] and well secured. Jim's accounting applications are also secured with very strong passwords.

The Solution

Jim re-configured [47] the firewall. It was quite easy and only took about five minutes to fix! Now all ports that should be closed are closed. Jim's computer is now invisible on the Internet!

Jim also reconfigured the anti-virus and anti-spyware to automatically to detect and fix any viruses, spyware and malware. [48] 

This incident highlights a very important point. It is not good enough just to have anti-virus software installed on your system. You need to have a number of security levels and they need to work together at all times!

Where Can I Find the Hardware that I Need to Keep My System Secure?

The most popular software firewall vendors are McAfee, Norton, and AVG. All the products that you need to secure your computer system can be purchased from our website online store. Alternatively, you can purchase them from any computer store.

On our website we provide product comparisons, expert reviews, interviews and a wizard to help you select a software solution which meets your budget and needs.

Further, all the products are really easy to install. I have included training videos which will give you the step-by-step procedures you need to install the products.

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