Firewall

A. Firewall Definition
Currently, the use of computer networks, both from the Local Area Network (LAN) to the internet, not an unusual thing anymore. Almost all business sectors and all information has been used and can be accessed via computer networks. In these conditions, the security of a network is important. One alternative to improve the security of computer networks is to use a method called network security with a Firewall. "A firewall is a way or mechanism that applies both to hardware, software, or systems with the aim to protect." (Anjik Sukmaaji & Rianto, 2008:187)
Protection can be done by filtering, limiting, or even reject one or all relations / activities of a segment on a private network with external networks that are not in scope. These segments can be a workstation, server, router, or local area network (LAN).
Firewalls can be hardware and software solution that restricts access between the internal network (network to be protected) to an external network (Internet) or vice versa.
In addition to the basic understanding about the Firewall, appear yag terms relating to the use of Firewalls, among others:
1. Host
A computer system that is connected to a network.

2. Bastion Host
The computer system should have a level of security / safety are high because these systems are very prone to attacks by hackers and crackers, because these machines are usually exposed to the outside network (Internet) and is the main point of contact of the user from the internal network.
3. Packet Filtering
Action of a selective devices to regulate the flow of data across a network. Packet filters can block or allow a packet of data across the network in accordance with the policy of the data flow is used (security policy).
4. Perimeter Network
An additional network located between a protected network with external networks, to provide an additional layer of a security system. Perimeter network is also often called a DMZ (De-Millitarized Zone).

B. Firewall Function
Firewalls have a main function is to maintain (Prevent) to access (inside or outside) of the person who is not authorized (unauthorized access) can not be done. However Firewall also has several other functions, among others:
1. To prevent a particular data stream. Every incoming or outgoing packets will be checked, whether or not such data in accordance with the criteria that exist on the safety standards defined in the firewall.
2. Firewall as a barrier to the outer segment. The firewall serves to protect by filtering, limiting, or even reject any or all relations / activities of a segment on a private network with external networks that are not in scope. These segments can be a workstation, server, router, or local area network (LAN).
3. Firewall to prevent viruses and other threats into the network. Firewalls prevent efforts Trojan horses, viruses, phishin, spyware to enter the destination system by preventing the relationship from the outside, except those earmarked for specific computers and ports.
4. The firewall will filter down and to audit the traffic that crosses the border between outside and within the network. Firewall is the focus of all decisions securities. This is because the firewall is a single point of exit point of the Internet traffic on a network.

C. Method or How Firewalls Work
Some of the methods used firewalls, among others:
1. Service control (control of the service)
Based on the types of services used and can be accessed either for inside or outside the firewall. The firewall will check the IP address numbers and also the port number used in both TCP and UPD, can even be equipped with software for proxy which will receive and translate every demand for a service prior permission.

2. Direction control (control of direction)
Under the direction of the various requests (request) to the services that will be recognized and allowed to pass through the firewall.
3. User control (control of the user)
Based on the user to be able to run a service, meaning there are users who can and who can not run a service. This is because users are not permitted to pass through the firewall.
4. Behavior control (control over their treatment)
Based on how benyak service that has been used. For example, firewalls can filter e-mail to overcome or prevent spam.

Firewall secures your computer or our internal computer network with a variety of ways, including:
1. Traffic that comes close (incoming network traffic) based on source or destination of such traffic, by blocking incoming unsolicited network traffic is the most common features provided by the firewall.
2. Closing the outgoing traffic (outgoing network traffic) based on source or destination of traffic. Firewalls can also filter out traffic from internal networks to the Internet, for example when we want to prevent users from accessing porn sites.
3. Closing the traffic based on content. More sophisticated firewalls can monitor traffic from content that is not desirable, such as integrated antivirus firewalls in which he can prevent the files infected by the virus into the computer or internal computer network that we have.
4. Report the traffic on the network and firewall activities. When monitoring the network traffic to and from the Internet, which is also important to know is what is done by the firewall, who tried to break into the internal network and who is trying to access information that is not worthy of the Internet.

D. Tool Used
Name of software: Sunbelt Personal Firewall 4.6.1861
Requirements: Windows 2000 / XP / Vista
Languages: en-US
License: Non-Commercial Freeware
Author: Sunbelt Software
www.sunbelt-software.com
Windows firewall (either XP or Vista) still have a poor level of security. This is what gives a false sense of security, because the windows firewall only filters incoming traffic. That means if malware has been working with the PC, then it can send all the personal info they have. Sunbelt Personal Firewall will filter traffic in and out and will keep it from hackers as well as personal data that we have. In addition, this software working with the VIPRE antivirus and antispyware.


REFERENCES

Anjik Sukmaaji & Rianto. 2008. COMPUTER NETWORKS. Yogyakarta: Andi Yogyakarta.

Nurcahyono, Nugroho. 2007. Information and Communication Technology for high school class XII. London: SMA Negeri 1 Sewon.

http://www.ilmukomputer.org/wp-content/uploads/2008/04/sriwijaya-firewall.doc

http://ilmukomputer.org/2009/02/28/penggunaan-firewall-untuk-menjaga-keamanan-sistem-jaringan-komputer/

http://www.filehippo.com/firewal/

Muammar, Ahmad. 2004. Firewall. Public Lecture IlmuKomputer.com

Agus Aan Soul P. 2009. Use of Firewalls to Maintain Computer Network Systems Security. Public Lecture IlmuKomputer.com

http://ilmukomputer.org/2009/02/28/penggunaan-firewall-untuk-menjaga-keamanan-sistem-jaringan-komputer/