OSI 模型 telnet 协议 FTP配置.pdf

OSI Model (Open System Interconnection) 开放式系统互联参考模型 Wednesday, February 29, 2012 10:14 AM It is used to identify how data is travelling from one Place to another, that means source to destination. 该模型是用来识别数据从一个地点是如何传送到另一地点的，也就是说从来源到目的地． The International Standards Organization 国际标准化组织(ISO) developed the OSI model. The OSI model has seven layers ＯＳＩ模型有７层 OSI Model Layers 应用层 Layer - 7 Application Upper Layer 上层 表示层 Layer - 6 Presentation or 或 软件层 Software Layer 会话层 Layer - 5 Session 传输层 Layer - 4 Transport Heart of OSI ＯＩＳ核心层 网络层 Layer - 3 Network Lower Layer 底层 数据链路层 Layer - 2 Data Link or 或 硬件层 Hardware Layer 物理层 Layer - 1 Physical 3 Application Layer 应用层 This layer is responsible for making an interaction between the application software and network services. It is also known as Desktop Layer. 该层负责在应用软件和网络服务之间建立互动，也叫做桌面层 Ports: 端口 Ports are entry and exit paths to a network. 端口是计算机与外界网络通讯交流的出口 端口总数：Total Port no.s: 0-65535 预留端口号：Reserved Ports : 0-1023 开放客户端端口：Open Client Ports : 1024-65535 Services Port nos.