about firewall

Firewalls: What It is and How It acts

If you already use the internet for some time, and especially if you work in a large company and browse the internet at work, you may have heard the term such as Zone Alarm firewall. As, for example, you often hear people say, "I can not to that site is because they do not allow through the firewall."

If you have a fast internet connection at home (such as D-Link DSL or cable modem), you also heard about using a firewall for network diperumahan. In fact, the network security of housing have the same problem with large companies. You can use a firewall to protect network of family housing and attack sites and the potential hacker.



Basically, a firewall is like a wall of the separator to prevent the damage we are far from home. In fact, the wall which is called a firewall set up to prevent the fire to spread from one place to another.

Firewall function

A firewall is software or hardware that filter (filter) the information entered via an internet connection to a private network or computer system. If the incoming packet of information by a filter, the package can not go in and have more removed.

Suppose you work in a company with 500 workers. So companies that have hundreds of computers that are connected with the network card. The company also has a connection to the internet through a T1 or T3 (such as cable modem, but for large companies). Without using a firewall, this will be hundreds of computers directly connected to the Internet. Hackers can analyze the computers that are used by accountants, for example, and trying to make earlier connections to the computer via FTP, telnet, or other means. If a worker makes a mistake and open a hole for hackers to enter, this hacker will controlling computer.

With a firewall, the situation will be changed. The company is installing a firewall ditiap connection to the Internet (for example, in each T1 into the company). In the firewall can be installed security regulations, for example:

Than 500 computers in this company, only one is allowed to receive FTP traffic. Computer must berubungan with this computer to use the FTP facility.

Companies can make the rules as above for the FTP server, Web server, Telnet server, and others. Companies can also mengkontrol employees how to access the Internet site, what can send the file out of the company through the network, etc.. Firewalls use one or more methods to manage the traffic entering the network-out:

* Packet filtering - Package data analyzed and compared with the filter. Pass the packet filter is sent to the requesting system and the rest will be discarded.
* Proxy service - Information from the exit-entry must be through the internet firewall. Example: Computer A requested information from the ABC site. A computer is not directly related to the ABC site, but the firewall will have this information, and after getting the computer to send akan A.
* Stateful inspection - a new method that does not check every package, but will compare the key part of the package with a database that contains reliable information. The information comes from the exit and in the firewall will be monitored for important characters, then enter the information will be compared with this character. If the comparison is quite close to this information will be entered are, if not will be removed.

Create Firewall Pas

Firewalls can be configured. This means you can increase or decrease the filter that will be used depending on the circumstances. Part of this filter is:

* IP address - Each of the components (computer, hub, print server, etc.) from the internet is given a unique address (does not have the same) and is called IP address. This address is 32-bit, shown as four "octets" to the point separator; example: 72164215216. Pengetrapan example, if a certain IP address outside the company too much to read from the file server, the firewall can be configured to mengeblok all traffic from this IP address.
* Domain names - Because very difficult because the sequence numbers that form the IP address, and sometimes because the IP addresses need to be replaced, all servers on the Internet also has a name that is easy to read, instead of the IP address, and called domain names. For example, www.howstuffworks.com is easier to memorize than 216.27.61.137. Pengetrapan Example: Company can mengeblok or give access to a particular domain.
* Protocol - Protocol is a way for someone who would like to use the service to communicate with the service. "A person" can mean people, or more likely to applications such as browser, telnet, or ftp. Sample protocol for example as a web http protocol. Protocols are often set in the firewall include:
o IP (Internet Protocol) - the system of information delivery via the internet
o TCP (Transmission Control Protocol) - used to build the reverse split and the information circulating on the internet. TCP requires answers from sipenerima back to menyakinkan that the package is sent and received to find out if packet should be sent back if lost.
o HTTP (Hyper Text Transfer Protocol) - used for Web pages
o FTP (File Transfer Protocol) - to download and upload files
o UDP (User Datagram Protocol) - TCP, but such answers do not need a back, such as streaming audio and video
o ICMP (Internet Control Message Protocol) - used by routers to exchange information with another router
o SMTP (Simple Mail Transport Protocol) - to send information in the form of a text (e-mail)
o SNMP (Simple Network Management Protocol) - to collect system information from remote computer
o Telnet - to run a command on the remote computer

Companies can configure one or two machines to handle a specific protocol and the protocol prohibits this in the other computer.

* Ports - Server provides a service to the Internet using a port number, one number for each service that is available on the server page. Example: HTTP (port 80), FTP (port 21).
* The word or words a particular - A firewall will detect all the packages that contain these words. You can configure the firewall to blocked the packages that contain the word "X-rated" or "XXX." The most important word filter should be really the same-"X-rated" not the same as the "X rated".

OS (operating systems) have a built-in firewall built, such as Unix or Linux, and Windows XP with SP-2. If not, the software firewall can be installed on the computer at home that have a connection to the Internet. This computer is considered a gateway because it provides a single point of access to housing with the internet network. With a hardware firewall, this unit usually functions as its own gateway. For example Linksys Cable / DSL router that has built-in Ethernet card and hub. Computers housing through the network to the router, and through this router to cable or DSL modem. You can configure the router via the browser.

Hardware firewall is very secure and not expensive. Versions for housing, including router, firewall and Ethernet hub for broadband connections can be obtained with the price under Rp. 1 million.

By Firewall Protection

Many ways for hackers to access or damage data on a computer that is not protected:

* Remote login - When people come in to your computer and can take control, can read files or run applications.
* Application backdoors - applications have a certain back roads that allow access to remote into the computer.
* SMTP session hijacking - SMTP is used to send email via the internet. With access to the list email, hackers can use this information to send spam or email junk to even hundreds of millions of people. This is usually done with the path email to the SMTP server has been hack, so this spam as if sent from this SMTP server. This makes tracking the sender of the original is very difficult.
* Operating system bugs - Like applications programs, operating systems sometimes have a "bug" that allows hackers to use this opportunity as the entrance.
* Denial of service - you may have heard this term from news about the attacks to a large site, such as Microsoft or Yahoo. This attack is very difficult to block. A hacker is going to send a request to connect with the server. When the server and ready to make a session, the server can not find this address request. By making such demand and so many, this server will be very slow and eventually crash.
* E-mail bombs - email bombs usually a personal attack. Send someone hundreds or thousands email the same until email server can not accept any more.
* Macros - Macro usually made to simplify the complex procedures and often repeated. Computer you can have a macro that bad because the hacker or you download the macros from the internet without you realize. This macro can delete the document / file, or make your system crash.
* Viruses - Viruses are small applications that can duplicate itself to other computers. Thus, this virus can spread quickly from one computer to another. This virus can be benign or malignant (harmful data).
* Spam - Usually tame but make peeved. Spam can be dangerous because it contains links to sites that wrong / false.
* Redirect bombs - Hacker can use ICMP to change the flow of internet traffic to another router. This is a way to set up denial of service attacks.
* Source routing - Generally, the path that must be adopted by the package of information on the Internet is determined by the router-router is skipped. But the source that provides the route this may give the wrong route or replaced by hackers.

Some of the topics mentioned above are very difficult, or even not possible, for the filter with a firewall. Although there is a firewall that provides protection such as anti-virus, install anti-virus computer in each give better protection. Although spam is spam, but fret will continue this through the firewall if you receive spam and open it. Security level determines how much of this threat can reduce by a firewall. A high level of security can blocking almost all threats. But this is likely to close the deal with the internet. How the block is usually used all the activities and select what is allowed. You can allow traffic is to be through the firewall so that only the specific information types, such as email, can be passed by. This is the way to business which has experienced network administrator. For all of us, should receive the configuration provided by the firewall unless there is reason to change.

One thing about best firewall securities viewed from the view is the possibility of a firewall to block outside access to computers in the network (behind the firewall wall). While this is very important for business, but the housing network have little or almost no threat like this. However, installing a firewall to provide security and sense of calm.