The Distributed Parallel Filtering Technology Of Firewall In Wide Band Circumstances

Now a day the development of the internet has widely spread the world. It surpassed the limitation of time and distance, made the world becoming a earth-village. And under the imitation of business, the internet developed much faster than pure technology. But meanwhile the internet becomes more and more dangerous.Firewall, as the main component of networking security, its performance is attached to more importance. The firewall has gone through 5 generations and the current main stream is firewall with state inspection. The main problem of the performance is searching of filter rules and state inspector table. There are a lot of researching done and being done in the world, but facing with the rapid progress of internet application, the performance is still unsatisfied. In many cases the firewall is still the choke point of the bandwidth.The thesis designed the structure of a firewall in global, and then it go deep into the problem of searching and maintaining the filter rules and the state inspection table. It employed the data structure and algorithms of geometry and graph theory in the design of firewall.In design of the filter rules, it takes the rules as a set of cuboids, and the searching process is transferred to a process of locating a point in these cuboids. With help of reference to some documents in geometry, it gave methods to solve of the problem.When discussed about the state inspector table, it employed key-tree as the storage method, but it improved the tree. It also gave the procedure about searching, inserting and deleting nodes in the tree.Besides the designing of data structure and algorithms, it made comparisons between its design scheme and some other schemers. It analyzed their advantages and disadvantages and made some advice for selecting the schemes.