In a computer network environment, software used to support data communications and various network activities. A system connected to a computer network usually configures different network application systems according to the characteristics, capabilities and service objects of the system itself. Its purpose is to share the resources of other systems in the network for the local user, or to provide the functions and resources of the local system to other users in the network. To this end, each computer network formulates a set of network protocols that the entire network abides by, and requires each host system in the network to configure corresponding protocol software to ensure that different systems in the network can communicate.
cooperate with each other reliably and effectively
Chinese name Network software Foreign name network software Classification Communication application Data transmission
1 Network operating system
2 Network communication protocols
3 Network classification
4 Software classification
▪ Communication software
▪ Protocol software
▪ Application system
5 Security Issues
6 Development trends
network operating system editor
A network operating system is a system software used to manage network soft and hard resources and provide simple network management. Common network operating systems include UNIX, Netware, Windows NT, Linux, etc. UNIX, a powerful time-sharing operating system formerly used on mainframes and minicomputers, has transitioned to PCs. UNIX supports the TCP/IP protocol, with strong security and reliability. The disadvantage is that the operation and use are complicated. Common UNIX operating systems include SUN’s Solaris, IBM’s AIX, and HP’s HP UNIX. Netware is an early local area network operating system developed by Novell. It uses IPX/SPX protocol. The latest version of Netware 5.0 in 2011 also supports TCP/IP protocol, with strong security and reliability. More complicated to use. WinNT Server is designed by Microsoft to solve the problem of PC server. The operation is simple and convenient. The disadvantage is that the security and reliability are poor, and it is used in small and medium-sized networks. Linux is a free network operating system. The source code is completely developed. It is a branch of UNIX. The kernel is basically the same as that of UNIX.
Editing of network communication protocols
A network communication protocol is an agreement between computers in the network to exchange information. It specifies the rules for computers to exchange information in the network. The protocol adopted by the Internet is TCP/IP, which is also the most widely used protocol until 2011. Other common protocols include Novell’s IPX/SPX.
Most computer networks organize computer network protocols according to a hierarchical model. IBM’s system network architecture SNA is composed of seven layers: physical layer, data link control layer, communication control layer, transmission control layer, data flow control layer, presentation service layer and end user layer. The network layer model with the greatest influence, the most complete functions and the best development prospect is the basic reference model of “Open Systems Interconnection (OSI)” proposed by the International Organization for Standardization (ISO). It consists of 7 layers including physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer. In terms of its overall function,
OSI network system model can be divided into two parts:
the communication support platform and the network service support platform.
The communication support platform consists of the bottom 4 layers of OSI (ie physical layer, data link layer, network layer and transport layer). , which is used to realize interconnection and intercommunication between open systems. The network service support platform is composed of the upper three layers of OSI (that is, the session layer, the presentation layer and the application layer). The application layer is further divided into two sub-layers, the common application service element and the specific application service element. The former provides general services unrelated to the nature of the application, including contact control service elements, entrustment and recovery, reliable delivery service elements, and remote operation service elements; the latter provides various capabilities that meet specific application requirements, including message processing systems, File transfer, access and operation, virtual terminal, job transfer and operation, remote database access, etc. It is used to provide a good operating environment and development environment for network users and application systems. Its main functions include unified interface management, distributed data management, distributed system access management, application integration, and a set of specific application support, such as electronic data interchange. (EDI), Office Document System (ODA), etc.
Network classification editing broadcast
Computer networks are divided into two basic forms: user entities and resource entities. User entities (such as user programs and terminals) are directly or indirectly related to users, reflecting the tasks and service requests to be completed by users, and resource entities (such as equipment, files and software systems, etc.) are related to specific resources, Provide services for user entities to access corresponding resources. Various entities in the network usually communicate with each other and cooperate with each other according to the common rules and agreements to complete the tasks of common concern. These rules and conventions are called computer network protocols (referred to as network protocols), and network protocols are usually composed of three parts: semantics, syntax and transformation rules. Semantics specifies what the two communicating parties are going to say to each other, that is, to determine the type of protocol elements; grammar specifies how the communicating parties “speak” to each other, that is, to determine the format of the protocol elements; transformation rules are used to specify the communication between the two parties. The “response relationship” of , that is, to determine the state change in the communication process, can usually be described by a state change diagram.
Software classification editing broadcast
Network software includes communication support platform software, network service support platform software, network application support platform software, network application systems, network management systems, and software for special network sites. It is not difficult to see from the network architecture model that communication software and network protocol software at various layers are the basis and main body of these network software.
Software used to supervise and control communications. In addition to being the basic component of computer network software, it can also be used as software for communication between computers and their own terminals or attached computers. Communication software usually consists of line buffer management program, line control program and message management program. The message management program usually consists of five parts: receiving, sending, sending and receiving records, error control, start and end.
An important part of network software. It is organized according to the protocol layer model adopted by the network (such as the basic reference model for open systems interconnection recommended by ISO). Except for the physical layer, most of the other layer protocols are implemented by software. Each layer of protocol software is usually composed of one or more processes, and its main task is to complete the functions specified by the corresponding layer protocol and interface functions with the upper and lower layers.
According to the purpose of network formation and business development, research, develop or purchase application systems. Its task is to realize various services stipulated in the overall network planning, provide network services and share resources. There are general-purpose and special-purpose network application systems. The general network application system is suitable for a wide range of fields and industries, such as data collection system, data forwarding system and database query system. The dedicated network application system is only suitable for specific industries and fields, such as bank accounting, railway control, military command and so on.
A really practical and highly beneficial computer network, in addition to the configuration of the above-mentioned various software, usually should also establish a perfect network application support platform between the network protocol software and the network application system, to create a good network for network users. operating environment and development environment. Computer networks with strong functions usually also set up some special host systems (such as network management centers, control centers, information centers, measurement centers, etc.) that are responsible for the operation of the entire network. For these special host systems, in addition to configuring various basic network software, it is also necessary to compile relevant special network software according to the network management work they undertake.
Security Issue Editing Broadcast
1) The loopholes and defects of the network software are exploited, causing the network to be invaded and destroyed;
2) The network software security function is not perfect or the “Trojan horse” software is installed;
3) The software that should be added with security measures may not be identified and protected, and the key programs may not have security measures, which may cause the software to be illegally used, destroyed or produce wrong results;
4) Users are not classified and identified, so that data access is not restricted or controlled, but is stolen or illegally processed by illegal users;
5) Wrong routing selection, choosing an inappropriate path for communication between one user and another;
6) Deny service, interrupt or hinder communications,
delay operations that require high time;
7) Information replay, that is, record the information and prepare it for replay after a period of time;
8) The requirements for software changes are not fully understood, resulting in software defects;
9) There is no correct security strategy and security mechanism, and there is a lack of advanced security tools and means;
10) Improper calibration or data, resulting in a version error of the modified program. Such as programmers did not keep records of program changes; did not make copies; did not establish a record keeping business.