The Design And Implementation Of U-disk Based Firewall

With the increasing popularity of computer network, the network as the world's largest database, to all the crowd offers many information, variety, high efficiency, transmit speed. However, the problem of network security, because the network of an increasingly large scope, bears all things, is inevitably some inappropriate content. All kinds of viruses, Trojan horses in the network, has some illegal wanton spread through the Internet site is the medium of wanton spread unhealthy content, corrosion people's hearts. Perhaps, our computers and, without any important information, however, is a loss of information loss. And, as the increasing popularity of e-commerce, similar to the dragons, whoever KeWang,transaction in the become more and more frequently, this means more online banking, credit CARDS and other important information-network. Internet not only delivers the information, also delivers the people important material and information, and thus firewall in network security role is especially important. Yet many small and medium-sized enterprise cannot afford professional commercial firewalls and cause internal network under attack, thus constructing a cheap firewall is urgently needed.U disk-based firewall is aimed at some small companies unable to afford a large, expensive firewall and the reality of the increasingly important issue of network security. We bring a very cost-effective solution:using some old-fashioned, even out of the upcoming computer in those companies to run a free and open source operating system: Linux. Using a very powerful software tool package named iptables in Linux kernel 2.4 and above to analysis and manipulate the network data packets. We can use iptables to realize a functional, relatively packet-filtering firewall after some appropriate configurations. Firewalls designed to achieve the basic steps are:(1). boot Linux operating system from U disk. (2) Programming to implement the firewall configuration for both local and remote.Firewall is also will not credible external network and credible intranets is separated, it can cut off the external network cracker attacks, malicious port visits and unauthorized login. Firewall is network defense line of defense, its stability is very important. This my graduation design is based on the design of a firewall, through U dish, using a under the environment of Linux kernel packet filtering the new management tools-iptables. This design is through the scripts and under Linux C language development local configuration program.The graduation design goal is also design such a based on U disk firewall software. Its basic function is the web page to filter content, it is prohibited to illegally characters from the packets, and for the gateway through the packet is released. The whole system is in place within U dish. And my main task is to establish the structure of data, build module, using C language and Linux program realization firewall.