application layer in osi model

presentation layer transforms the upper data or information to ensure that one host application layer information can be understood by another host's application. The data transformation of the presentation layer includes data encryption, compression, format conversion, and

1.1Network layering This course mainly introduces two different layers:OSILayered Model andCiscoLayer-3 model.Advantages of layering:1. Divide complex networks into layers that are easier to manage.2. When a layer is changed, other layers are not affected, which makes the applicationProgramDevelopers can perform specific design and development.3. In today's network environment, no manufacturer can provid

This section summarizes the overall framework of network communication and its underlying process. We have learned about the creation and application of sockets, in fact, we are only using sockets this tool, the underlying details of which we are shielded. To complete the data transmission through the Internet, in fact, not only software can be solved, but also need to build hardware systems. Therefore, in order to solve this problem, many ex

fileD catalog FileL Link FileNine-bit master permission U master privilege g other person permissions OR-Read 4W Write 2X execution 12 Modify Permissionschmodchmod u+x aa aa file owner plus execute permissionchmod u-x AAchmod g+w,o+w AAchmod U=rwa AAchmod 755 AAchmod 644 AA4 Generic and Group commandsChown user name filename Change file ownerChown user1 AA user1 must existChown user1:user1 aa Change Genus master simultaneous change groupUseradd User name Add userpasswd User Name setting passwor

called a segment. Session Layer: Establish, manage, and terminate sessions. That is, through the transport Layer (port number: Transport port and receive port) to establish the path of data transmission, mainly between your system to initiate a session or accept a session request (between the devices need to know each other can be IP or Mac or host name). Presentation

browsing port, primarily for HTTPS services, and is another HTTP that provides encryption and transmission over a secure port.1024 Port: 1024 port is generally not fixed assigned to a service, the explanation in English is "Reserved" (reserved).1080 Port: 1080 port is the port used by SOCKS Proxy service, and the WWW service used by everyone in the Internet is the Proxy service of HTTP protocol.8080 Port: 8080 port with 80 port, is used for WWW Proxy service, can realize browsing Web page.iOS s

Friends who are interested in network programming may have heard of the OSI seven layer model, and the next one is a diagram of the entire protocol implemented under Windows. Implementation structure of the OSI seven layer

These are my interpretations of OSI. They are not very rigorous, but very simple:① Physical layer: define what is 0 and what is 1② Link layer: communication between two points directly connected through Homogeneous Media (Use MAC address)③ Network layer: any connected communication between two points (Use IP Address)④

ISO: International Organization for StandardizationOSI: Open Systems Interconnection modeliOS: In a computer network, iOS is the Internet operating system and is the operating maintenance system developed by Cisco for its network equipmentSeven-layer model introduction1-7: Physical Layer--Data link layer--network

Application layer: An application that can generate network trafficPresentation layer: Encrypt and compress binary ASCII to represent contentSession Layer: Server and client establish connections and maintain session communication NETSTAT-NBTransport

the data will be re-sent if no acknowledgement has been received within the specified Time.Monitor Service Quality.Session LayerThe session layer, the 5th layer of the OSI model, is the interface between the user application and the network, and the main task is to provide

The OSI reference model has many similarities with the TCP/IP reference model. They are based on the concept of an independent protocol stack. In addition, the features of the layer are similar. For example, in the two models, the transmission layer and above all provide end

layer: spdu--represents the Protocol data unitDigital representation of your data (English/Chinese/Picture/mp3 ...) Translated into 01 formats via a certain rule)EncryptionCompressionApplication Layer: apdu--Application Protocol Data UnitInterfaces to provide services to users2.TCP/IP Four-layer network modelThe above

three times handshake mechanism. Like the current popular SYNFlooding attack, ACK flooding attack and so on are the use of TCP three times handshake mechanism. Attacks on UDP protocols, mainlyTraffic attack, enhance the reliability of UDP communication, in order to achieve the purpose of denial of service. Therefore network isolation must be strippedTCP/UDP agreement.Attack on the session layer of the OSI

more and more complex, and the network devices between the manufacturers are mostly incompatible and difficult to communicate.In order to solve the network compatibility problems, to help manufacturers to produce compatible network equipment, ISO in 1984, the OSI RM (Opensystem interconnection Reference model, open System Interconnect Reference Model). The

In this topic, we will discuss network security from the perspective of OSI hierarchy. We will study the OSI stack in depth from the physical layer to the application layer. Starting from analyzing vulnerabilities at each layer, t

TCP/IP Reference Model OSI Reference Model Application Layer Application Layer Presentation Layer

classParent: Save ();Return $ this;}} The settlement code is easy to understand:1. Call the checkout () method of the shopping cart.2. Start the database transaction. In this way, when the order fails to be saved (for example, the inventory quantity is insufficient), the database will be rolled back to ensure that the database content is not affected.3. Add all items in the shopping cart to the order4. Call the SAVE () method of the Order object4.1. traverse all items of the Order to reduce th

: The same information can be displayed in different Windows Data changes are immediately reflected in the display window user interface is easy to change and can even be changed at run time Different user interface styles do not affect the core logic of the application Fishigui MVC pattern for the application layer: