Two Kinds Of Implementations Of Computer Network Attack

As technology advances, the development of computer network (computer network) alter from day to day. The computer network security situation become more serious. According to the new era based on army building guidelines of the Central Military Commission, our army need to alter from quantity to quality-oriented, speed up the pace of informatization construction, however computer network security also as an important component of information sites are increasingly getting the unit leadership attention.In order to standardize the network-building and strengthen our military's network security, this paper from a remote network as the background, mainly discussed about two kinds of network offense:denial of service attacks (Denial of Service, DoS) and the Trojan horse of intrusion. As well as the mode of attack on these two principles, implementation method, and the use of Trojan intrusion designed a network attack systems, and their realization, the last part of paper builts a small network environment and tests the network attack system.Denial of service attack is directly or indirectly to attack the server in order to make it is paralyzed and could not be normal service, its attack pattern can be divided into direct attack methods (Direct Attacks) and reflection attacks (Reflector Attacking). The paper is based on the TCP protocol. It first analyzes the transmission principle of the TCP protocol, and then find the shortcomings by analyzing, as both a client request to the server, the client will establish a "semi-connection" with the server and the server will give "semi-connection" the allocation of certain resources to meet the needs of the session at this time if the client disconnects the server will continue to wait for some time to complete the customer's request may be issued, if the TCP protocol to use this feature can be a large number of fake "semi-Connect "request, so that the target server for these" semi-connection "to allocate substantial resources, which is the normal connection requests can not be responding, to create a server denial of service results.Trojan invasion as a common network intrusion methods and their impact is also growing. When we are researching the Trojan invasion, we use remote control technology, to build a network of long-range strike systems, including the client (Client)/communications terminal (Message)/server (Server) program, which placed in the control client side and service side placed in the controlled side, the client and server connections through the communication terminal to complete the remote control function. In this paper, class diagram, interaction diagram of the manner of the attack on the overall framework of the system design, and focuses on the server used in a variety of new network intrusion technology and feature implementation.Server-side technologies included are:1. Port rebound; "Port rebound" type of network attack system, a remote server using an active port, the client to use passive ports. When you want to make a connection, a request by the client, and enter the listening state, the server on a regular basis to read with the HTTP protocol request to take the initiative to connect.2. Link encryption:For between the two network nodes of a particular communication link, link encryption for data transmitted over the Internet to provide security guarantees, but also enables the network to transmit commands and data through the firewall to intercept. For link encryption, all messages encrypted before being transmitted, docking at the destination node to decrypt the message received.3. HTTP Tunnel technology:a "tunnel technology" in the "client" and "server" to communicate, such as when to send commands or files, all the contents of the package sent by post, load HTTP protocol, using HTTP protocol for data transmission, in order to escape the firewall blocking.4. Multi-threading: Thread is the implementation of the order of program instructions. Usually the operating system (OS) relies on the operating system threads and quickly switch between threads to achieve the program threads to run simultaneously and give people a sense of running. By the application of multi-threading technology, our software makes the clients can monitor multiple ports at the same time and one client can control multiple server.In addition, in the graduation design, socket design is become better than the previous design ideas. Communication terminal is a detailed analysis of the HTTP transport protocol packets based on the characteristics of the client and server-side to allow for communication between his mask, so that the content of communications in line with HTTP protocol requirements, in order to achieve the purpose of covert transmission, was found to reduce possible.Finally, on top of this system to build a small network environment, the various functions of the system experiment in building a network of two hosts are installed on the client, server-side, in the third host to create a an FTP server to place the attack on the system configuration files and download the required server-side. When the server is downloaded and, after running through the FTP server, get the configuration file with the client to establish a connection, you can by the client to the server-side where the host corresponding control.Through the above two kinds of network attack methods research, we will have a clearer understanding of network security. In the network war, I will learn to use the above for our military's network security built up a solid Great Wall and be able to take advantage of new budding network attacks means of pre-emptive strike, and firmly grasp the initiative in network warfare to achieve informatization construction of our army the general requirements.