计算机网络基础知识课件英文版.pptx
Computer Network Fundamentals PPT Courseware EngliCATALOGUE目录IntroductionNetwork ComponentsNetwork TopologiesNetwork ProtocolNetwork SecurityConclusionIntroduction01Summary The definition of a computer network is a system that allows multiple computers to connect and exchange informationDetails A computer network is a system that insists of multiple computers connected through communication channels These computers can exchange information,share resources,and perform tasks collaboratively Networks can be classified as local area networks(LANs)or wide area networks(WANs),depending on the size and scope of the connectionDefinition of Computer NetworkSummary:Computer networks can be classified based on their size,scope,and topologyDetails:Networks can be classified as local area networks(LANs)or wide area networks(WANs)based on their size and scope LANs typically cover a small geographic area,such as an office or a building,while WANs cover a larger area,such as multiple buildings or even entire counties Networks can also be classified based on their topology,such as star,ring,mesh,or bus networksClassification of Computer NetworksThe Importance of Computer NetworksSummary:Computer networks play a critical role in todays society,facility communication,information exchange,and collaborationDetails:Computer networks have become an integral part of modern life,connecting people across the globe and enabling the exchange of information at unexpected speeds Networks allow individuals and businesses to collaborate,share data and resources,and improve productivity They also facilitate communication,allowing people to stay connected with friends and family far away In addition,computer networks are essential for accessing and sharing information,making it easier to access the latest news,research,and educational resourcesNetwork Components02Hardware Components01Transmission Media02Coaxial cables:used for high speed LANsTwisted pair cables:used for telephone lines and most common Ethernet cables03Hardware ComponentsFiber optical cables:used for long distance transmissions and high speed LANsNetwork Interface Cards(NICs)These are expansion cards that are installed into personal computers to enable them to send and receive data over a networkHardware ComponentsHardware ComponentsThey contain a network controller that handles the physical layer of the OSI modelHubs,Switches,and RoutersHubs are simple devices that connect multiple nodes together and broadcast every message they receive to all other connected nodesSwitches are more advanced devices that learn the physical addresses of the connected nodes and only send messages to the destination nodeRouters connect different networks and forward data packets between different networks based on the destination IP addressHardware ComponentsNetwork Operating System(NOS)A NOS is a software program that controls the basic operations of a computer networkSome examples of NOSs are Windows Server,Linux,and Novell NetworkSoftware ComponentsSoftware ComponentsClient Server SoftwareClient software is responsible for sending and receiving data from other computers on the networkServer software provides resources to client software requests,such as shared files,printers,or internet connectivity03Some common protocols are TCP/IP,HTTP,FTP,SMTP,and POP301Protocol Software02Protocol software is a set of rules that govern how computers on a network send and receive dataSoftware ComponentsNetwork Topologies03在此添加您的文本17字在此添加您的文本16字在此添加您的文本16字在此添加您的文本16字在此添加您的文本16字在此添加您的文本16字Bus Topology:A linear topology where all devices are connected to a single cable(bus)and communication sockets between devices on the busCharacteristicsSimple to install and configureEasy to expand by adding drop cables to the main busSingle point of failure:if the bus fails,all devices are disconnectedLimited distance:Physical length of the bus limits the number of devicesBus TopologyStar Topology:Each device is connected directly to a central hub or switchCharacteristicsEasy to install:each device connects directly to the central pointCentral point of failure:if the hub or switch fails,all devices lose connectionEasy to troubleshoot:checking the central point reviews all connected devicesExpansion is limited by the number of ports on the central deviceStar Topology在此添加您的文本17字在此添加您的文本16字在此添加您的文本16字在此添加您的文本16字在此添加您的文本16字在此添加您的文本16字Ring Topology:Devices are connected in a closed loop,data travels in one direction around the ringCharacteristicsHigh fault tolerance:if a segment fails,the ring can still operateComplex to install and configureDifficult to expand without disrupting the ringHigh cost due to specialized equipment requiredRing TopologyMesh Topology:Each device is connected to multiple other devices,forming a network of connected nodesCharacteristicsHigh fault tolerance:multiple paths between devicesComplex to install and configureHigh cost due to cables and connections requiredScalability can be limited by the number of devices and connectionsMesh TopologyCharacteristicsFlexibility in design:combines characteristics of different topologiesMay require specialized equipment or software support for different topologiesComplex to install and configureHybrid Topology:A combination of two or more topologies,used to leverage their prospective advantagesHybrid TopologyNetwork Protocol04VSThe TCP/IP protocol suite is the core protocol of the Internet,consisting of Transmission Control Protocol(TCP),Network Protocol(IP),and other auxiliary protocols.TCP is a connection oriented protocol that provides reliable data transmission services,ensuring that data is transmitted in the order it is sent.TCP/IP Protocol SuiteIP is a network layer protocol responsible for transmitting data from one network node to another.Auxiliary protocols include Address Resolution Protocol(ARP),Reverse Address Resolution Protocol(RARP),Dynamic Host Configuration Protocol(DHCP),etc.TCP/IP Protocol SuiteHTTP Protocol01Hypertext Transfer Protocol(HTTP)is a protocol used to transfer hypertext(such as web pages).02HTTP is a stateless protocol,which means that the server will not maintain a state for every request.03HTTP also supports a request/response model,where the client sends a request to the server and the server returns a response.04The main characteristics of the HTTP protocol include simplicity,speed,flexibility,connectionlessness,and statelessness.输入标题02010403DNS ProtocolDomain Name System(DNS)is a service that converts domain names into IP addresses.The DNS protocol is crucial for the normal operation of the Internet,as it allows users to access websites through memorable domain names.DNS servers are distributed globally and organized through a hierarchical structure,with the root server being the top-level server.The DNS protocol is used to query IP addresses and other related information corresponding to domain names.File Transfer Protocol(FTP)is used to transfer files over a network.FTP supports two modes:active mode and passive mode.In active mode,the client sends data to the server;In passive mode,the server sends data to the client.The FTP protocol is widely used in scenarios such as file downloading,uploading,and synchronization,and is a common file transfer method on the Internet.FTP uses a client/server architecture,where the client interacts with the server through FTP commands.FTP ProtocolNetwork Security05FirewallsFirewall definition:A firewall is a network security system used to block unauthorized access and data transmission.It can prevent external threats from entering the internal network while allowing legitimate network traffic to pass through.Firewall types:According to their working principles and application scenarios,firewalls can be divided into packet filtering firewalls,proxy server firewalls,and stateful detection firewalls.Firewall deployment:Firewalls are usually deployed at the network entrance as a security barrier between the internal and external networks.It can filter and filter network traffic based on preset security policies.Limitations of firewalls:Although firewalls are an important component of network security,they cannot fully prevent all network threats.It is necessary to combine other security measures,such as intrusion detection systems,encryption technologies,etc.,to improve network security protection capabilities.Encryption TechniquesDefinition of encryption:Encryption is the process of converting plaintext information into ciphertext using a specific algorithm to protect the confidentiality and integrity of data.Only those who hold the correct key can decrypt and read the original data.Common encryption types:According to the usage of encryption keys,encryption can be divided into symmetric encryption and public key encryption.Symmetric encryption uses the same key for encryption and decryption,while public key encryption uses different keys for encryption and decryption operations.The application of encryption in networks:In network communication,encryption technology is widely used to protect the confidentiality of data,such as the SSL/TLS protocol used to secure the transmission of online transactions and login credentials.The challenge of encryption technology:With the improvement of computing power and the development of password analysis technology,encryption algorithms need to constantly evolve and update to cope with new threats and challenges.Viruses and WordsDefinition of Computer Virus:A computer virus is a malicious software program that can replicate itself and spread between computers,typically infecting the system by attaching to other programs or files.The transmission mode of viruses:viruses can spread through various channels such as email attachments,network sharing,and removable storage devices.Once infected,the virus may damage system files,steal personal information,or cause other damage.Introduction to Worm Virus:A worm virus is a type of virus that spreads independently of the host program.It spreads by scanning vulnerabilities in the network,similar to the way bacteria in the biological world reproduce.Preventive measures:The key to preventing virus and worm infections is to take a series of security measures,such as installing antivirus software,regularly updating system and application security patches,and not opening emails and links from unknown sources at will.Social Engineering AttacksSocial engineering attack definition:Social engineering attack is a type of attack that utilizes the weaknesses of human psychology and social behavior.Attackers obtain sensitive information or manipulate the behavior of victims through deception,inducement,and other means.Common social engineering techniques,such as impersonation,setting up phishing websites,and creating emergency situations,are used to lure victims into leaking personal information or performing malicious operations.Measures to prevent social engineering attacks:Improving user security awareness is the key to preventing social engineering attacks,including educating users to identify suspicious information and links,handling personal privacy information with caution,and not trusting requests from strangers.The harm of social engineering attacks:Social engineering attacks often bypass technical protection measures because they exploit weaknesses in human psychology and social behavior.Therefore,preventing social engineering attacks requires multiple efforts,including improving personal security awareness and strengthening network security education.Conclusion06Summary of the Main PointsImportance of Computer Networks:Computer networks have become integral to business,entertainment,and communication,making understanding their fundamental principlesNetworking Components:The course covered the essential components of computer networks,including routes,switches,and hubsPolicies and Standards:An overview of the various protocols and standards that govern computer networks was providedSecurity Considerations:Important security measures and best practices to ensure network integrity and data protection were discussedFuture Trends in Computer Networks5G and Beyond:The evolution of fifth generation(5G)wireless technology and its potential impact on computer networks,including higher data rates and lower latencyCloud Computing:The increasing trend of moving computing resources to the cloud,along with the associated challenges and opportunitiesIoT and Smart Devices:The integration of internet connected devices and sensors into computer networks,leading to more intelligent systems and data driven decision makingAI and Machine Learning in Networks:The potential for artificial intelligence(AI)and machine learning to optimize network performance,detect anomalies,and improve securityTHANKS感谢观看
