Researches And Implementation Of A Personal Firewall Based On SPI And Immune Ability

Internet hackers know thousands of ways to break into vulnerable PC systems. In seconds, they can steal private files, credit card information, tax records, passwords and Social Security Numbers. Remote hackers can even hijack person computer system to send spam messages. Or plant destructive viruses.A firewall is hardware, software, or a combination of both that is used to prevent unauthorized programs or Internet users from accessing a private network. All information entering or leaving the network must pass through the firewall, which examines the information packets and blocks those that do not meet the security criteria. A personal firewall performs these functions for a single computer. It's a piece of software or hardware that creates a protective barrier between personal computer and potentially harmful content on the Internet.Stateful Packet Inspection (SPI or dynamic packet filtering) is a firewall security technique. SPI inspects the contents of packets, monitoring traffic, including a history of the source of packets. A stateful firewall needs to keep track of the communication status between a source and destination host. This information is stored in what is called a "state table". The Transmission Control Protocol (TCP) is a connection oriented, session based protocol that is truly stateful. TCP has true start and finish states, as well as a number of intermediate states. A firewall can draw a fine bead on the status of a TCP connection because of the granularity of state information provided by TCP.Because a firewall is the most important first line of defense for computer security, the problem that how to protect the firewall system itself from attack has been becoming more and more important. Immunologists have traditionally described the problem solved by the immune system as the problem of distinguishing "self from dangerous "other" (or "nonself) and eliminating dangerous nonself. The problem of protecting computer systems from malicious intrusions can similarly be viewed as the problem of distinguishing self from nonself. Nonself might be an unauthorized user, foreign code in the form of a computer virus or worm, unanticipated code in the form of a Trojan horse, or corrupted data.This paper introduces the researches and implementation of a stateful inspection personal firewall ground on MS Windows system. The firewall's filter mechanism of stateful information is combined with its reserved mechanism by adding stateful inspection module to the package filter mechanism. In addition, this firewall is fairly provided with the immune ability to protect itself from attack. It is not a real immune system. Actually, its implementation of the immune ability found on cryptology.