Software Firewall

You may have heard the term firewall. If you have a network of computers (say 50 computers in the network) you will implement a firewall to protect your network from the cyber attacks. A firewall controls the ports that are used to communicate with the network. You can implement your own laws concerning the security of the network. You can allow the FTP to restricted number of computers. You can also regulate the computer from visiting certain restricted sites. If the network is large the security must be as tight. But what about the case of one or two computers connected to the internet ? The software firewall is the solution. Te software firewall examines the ports connected to the internet and regulates it. It also asks the user whenever an applicayion installed in the computer try to access the internet. Thus we can prevent unwanted usage of the internet by the unknown application. This also saves our band width. The usage of internet connection by the unknown application is generally a trojan or spyware.
The usage of the software firewall is not limited to the small network. It is also used in the huge network to regulate the usage of the internet by the employees.

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The firewall uses the following ways to prevent the unwanted data transfer through the internet.

• Proxy Service: The information received from the internet is received and it is forwarded to the requesting system. It can also receive the information (request) sent by a computer in the network and forward it to the corresponding destination.
• Packet Filtereing: The information to be sent are breakdown into small units and are converted to packets. These packets are first received by the firewall and checks it with a set of predefined filters. The firewall allows only the trusted packets to pass to the requesting computer.
• Stateful Inspection: It is a newer method. It does not checks the whole packet. Instaed it checks for only certain parts of the packet. It checks specific part of the data while sending the request and compares it with the incomming packets. If a match is found the packet is considered as a trusted packet and allowed to pass through the network otherwise it is blocked.
  

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Computer virus strikes US Marshals, FBI affected

A mystery computer virus affected the computer networks of the US Marshals and FBI. Both of them had shut down their network to prevent further spreading and destruction. The computer network have been disconnected from the Justice Department as a preventive measure. The problem of virus starts in the Thursday. The origin of the virus has not been identified. Besides the external network, the law enforcement department has its own internal network to prevent the snoopers from accessing the sensitive data. The internet access and e-mail services of the US Marshals and FBI had been disabled while the staff worked on the problem.

Resident Virus

As you know a virus will normally infect an executable file and it will be executed when the infected file is executed. According to the mode of infection the viruses are divided into resident and non-resident viruses. The non resident virus has a module to find the files that it can infect and it also has another module called replication module which will infect the file encountered by the finding module. After infecting a particular file the virus will be executed when the infected file is executed.
In the case of the resident virus, the thing is different. They first infect a file or executed by some other means. When they are executed it loads its replication module into the memory. By working in the memory it is capable of infecting the files to a great extend. So there are two types of resident viruses- those which are capable of infecting large number of files in a short duration called fast infectors and the other that infects less number of files. The fast infecting type virus is somewhat more dangerous since it infect more potential programs in a short duration. If the infected potential files include the files of the antivirus then there is a chance of infecting the files scanned by the antivirus. The fast infecting virus shows the symptoms of infection very soon, mostly by slowing down the PC. There are antiviruses that will be active when there is an abnormality is identified and it will disinfect the infected file. In the case of slow infectors, they do not show the symptoms of infection as slowing downing the PC. This makes them less chance to be identified by the antivirus. But do not remain unidentified forever. Since it shows the signs of infection very late, they are identified very late. However it is less dangerous than that of the fast infectors.