This document provides an overview of the TCP/IP protocol suite. It begins by defining what TCP/IP is, noting that it is a set of protocols that allow cooperating computers to share resources across a network. TCP/IP is made up of the TCP and IP protocols at the transport and network layers respectively. The document then discusses specific protocols at each layer, including application layer protocols like FTP, SMTP, and HTTP, as well as transport layer protocols TCP and UDP. It also covers network layer protocols like IP, ARP, and ICMP. The document concludes by discussing TCP/IP addressing schemes and how networks are divided into subnets.
The document provides an overview of the TCP/IP protocol stack, including its layers and core protocols. It discusses the four layers of TCP/IP - network interface, internet, transport and application layers. Key protocols like IP, TCP, UDP, ARP are explained along with their functions. The relationship between TCP/IP and OSI models is covered. The use of ports, common port numbers, and risks of open ports are also summarized.
This document provides an overview of configuring TCP/IP on Red Hat systems. It discusses configuring the hostname, assigning IP addresses, defining routing information and gateways, and defining name resolution. The modules cover setting the hostname, assigning IP addresses using ifconfig, defining the default gateway, and name resolution using hosts and DNS files. Labs are included to practice these TCP/IP configuration topics. The document is copyrighted and provides contact information for the author.
The document describes the RHCE certification and provides an overview of an RHCE training book. It includes sections on RHCSA and RHCE certifications, an overview of the book's contents including copyright information, and course requirements. The book covers topics like system startup and shutdown, system administration tools, packaging tools, file systems, rescue mode, partitioning, and more. It provides contact information for the book's author and links for purchasing the book.
This document provides an overview of basic Linux commands and system usage. It discusses logging into and out of Linux systems, the structure of Linux commands, and executing basic commands such as date, cal, who, finger, clear, echo, write, wall, talk, and mesg. It also covers changing passwords and using command history. The document is intended to teach Linux fundamentals and common tasks for system usage.
HTTP is the application-layer protocol for transmitting hypertext documents across the internet. It works by establishing a TCP connection between an HTTP client, like a web browser, and an HTTP server. The client sends a request to the server using methods like GET or POST. The server responds with a status code and the requested resource. HTTP is stateless, meaning each request is independent and servers do not remember past client interactions. Cookies and caching are techniques used to maintain some state and improve performance.
HTTP/2 is an updated protocol that improves upon HTTP/1.1 by allowing multiple requests to be sent simultaneously over a single TCP connection using multiplexing and header compression. It reduces latency compared to HTTP/1.1 by fixing the head-of-line blocking problem and prioritizing important requests. Key features of HTTP/2 evolved from the SPDY protocol and include multiplexing, header compression, prioritization, and protocol negotiation.
HTTP is the most popular application protocol on the internet. It uses the client-server model where an HTTP client sends a request to an HTTP server using a request method like GET or POST. The server then returns a response with a status code and can include a message body. A URL identifies a web resource and includes the protocol, hostname, port, and path. HTTP specifications are maintained by the W3C and the current versions are HTTP/1.0 and HTTP/1.1. The HTTP request and response include a start line, headers, and optional body. Common status codes indicate success, redirection, or client/server errors.
The document discusses various networking concepts including routers, NAT, proxy servers, TCP/IP configuration, Internet Explorer security settings, Outlook/Outlook Express, DHCP, DNS, hostnames, FQDN, and NetBIOS. Routers are used to connect different networks and forward data packets using static or dynamic configuration. NAT allows private networks to use different addressing than public networks and provides security benefits. Proxy servers provide caching and security when accessing the internet.
The document provides an overview of the TCP/IP protocol stack, including its layers and core protocols. It discusses the four layers of TCP/IP - network interface, internet, transport and application layers. Key protocols like IP, TCP, UDP, ARP are explained along with their functions. The relationship between TCP/IP and OSI models is covered. The use of ports, common port numbers, and risks of open ports are also summarized.
This document provides an overview of configuring TCP/IP on Red Hat systems. It discusses configuring the hostname, assigning IP addresses, defining routing information and gateways, and defining name resolution. The modules cover setting the hostname, assigning IP addresses using ifconfig, defining the default gateway, and name resolution using hosts and DNS files. Labs are included to practice these TCP/IP configuration topics. The document is copyrighted and provides contact information for the author.
The document describes the RHCE certification and provides an overview of an RHCE training book. It includes sections on RHCSA and RHCE certifications, an overview of the book's contents including copyright information, and course requirements. The book covers topics like system startup and shutdown, system administration tools, packaging tools, file systems, rescue mode, partitioning, and more. It provides contact information for the book's author and links for purchasing the book.
This document provides an overview of basic Linux commands and system usage. It discusses logging into and out of Linux systems, the structure of Linux commands, and executing basic commands such as date, cal, who, finger, clear, echo, write, wall, talk, and mesg. It also covers changing passwords and using command history. The document is intended to teach Linux fundamentals and common tasks for system usage.
HTTP is the application-layer protocol for transmitting hypertext documents across the internet. It works by establishing a TCP connection between an HTTP client, like a web browser, and an HTTP server. The client sends a request to the server using methods like GET or POST. The server responds with a status code and the requested resource. HTTP is stateless, meaning each request is independent and servers do not remember past client interactions. Cookies and caching are techniques used to maintain some state and improve performance.
HTTP/2 is an updated protocol that improves upon HTTP/1.1 by allowing multiple requests to be sent simultaneously over a single TCP connection using multiplexing and header compression. It reduces latency compared to HTTP/1.1 by fixing the head-of-line blocking problem and prioritizing important requests. Key features of HTTP/2 evolved from the SPDY protocol and include multiplexing, header compression, prioritization, and protocol negotiation.
HTTP is the most popular application protocol on the internet. It uses the client-server model where an HTTP client sends a request to an HTTP server using a request method like GET or POST. The server then returns a response with a status code and can include a message body. A URL identifies a web resource and includes the protocol, hostname, port, and path. HTTP specifications are maintained by the W3C and the current versions are HTTP/1.0 and HTTP/1.1. The HTTP request and response include a start line, headers, and optional body. Common status codes indicate success, redirection, or client/server errors.
The document discusses various networking concepts including routers, NAT, proxy servers, TCP/IP configuration, Internet Explorer security settings, Outlook/Outlook Express, DHCP, DNS, hostnames, FQDN, and NetBIOS. Routers are used to connect different networks and forward data packets using static or dynamic configuration. NAT allows private networks to use different addressing than public networks and provides security benefits. Proxy servers provide caching and security when accessing the internet.
Wireshark is a network protocol analyzer that intercepts and logs traffic passing over the network. It captures packets, decodes and analyzes their contents. Wireshark can be used for troubleshooting network problems, analyzing network performance, network intrusion detection, and analyzing application operations. It is a free and open-source packet analyzer that runs on Linux, macOS, and Windows.
This document provides an overview and introduction to a course on Internetworking with TCP/IP. It outlines the topics that will be covered, including terminology, concepts, protocols, architecture, and applications. It also discusses the history and development of TCP/IP, the organizations involved, and how protocol specifications are documented.
HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files between clients and servers on the World Wide Web. Communication occurs through HTTP requests from clients to servers and HTTP responses from servers to clients. A typical request/response cycle involves a browser requesting an HTML page from a server, which returns the page, and then the browser requesting and receiving additional files like stylesheets, images, and JavaScript code referenced in the HTML. An example is provided of an HTTP request from a browser to a server for a youtube.html page and the corresponding response.
The document discusses considerations for supporting legacy analogue devices in a Unified Communications project using Microsoft Lync. It describes three options for faxing - bypassing Lync, fax hairpinning within Lync, or faxing via an SBC and SIP trunk. It also provides details on configuring an analogue gateway and extensions in Lync topology builder and Active Directory to integrate analogue devices into the UC system.
Web Server Technologies I: HTTP & Getting StartedPort80 Software
Introduction to HTTP: TCP/IP and application layer protocols, URLs, resources and MIME Types, HTTP request/response cycle and proxies. Setup and deployment: Planning Web server & site deployments, Site structure and basic server configuration, Managing users and hosts.
PLNOG 9: Ivan Pepelnjak - OpenFlow and SDN: hype, useful tools or panacea?PROIDEA
This document discusses OpenFlow and Software Defined Networking (SDN). It begins with an introduction of the author, Ivan Pepelnjak, and his background. It then reviews what OpenFlow is, including separating the control and data planes and using OpenFlow as a protocol to download forwarding tables to switches. The document discusses some OpenFlow use cases like topology discovery. It also addresses questions around whether OpenFlow will replace existing routing protocols. Overall, the document provides an overview of OpenFlow and SDN, discussing concepts, use cases, and debates around the technology.
The document provides information on the TCP/IP protocol suite including:
- TCP/IP has 4 layers (Application, Transport, Network, Data Link) compared to OSI's 7 layers.
- Common application layer protocols include FTP, Telnet, SMTP, HTTP.
- Transport layer protocols are TCP and UDP which provide reliable and unreliable data transmission.
- Network layer protocols like IP, ARP, and ICMP handle routing and addressing.
- Layers communicate through encapsulation where each layer adds its own header to protocol data units.
TCPLS closely integrates TCP and TLS by using new TLS record types to carry TCP control plane information. This allows TCP options and control data to be encrypted and authenticated within TLS records. TCPLS provides benefits like securing Multipath TCP connections, enabling stronger TCP Fast Open, providing more space for TCP options, allowing true TCP keepalives, securely releasing TCP sessions, supporting Happy Eyeballs, and enabling connection migration. The integrated TCPLS protocol could improve privacy, security and functionality compared to treating TCP and TLS as separate and independent protocols.
Keynote given at DRCN2018, shows that innovation is back in the transport and network layer with a description of Multipath TCP, QUIC and IPv6 Segment Routing.
mod_ftp is a module for Apache HTTP Server that implements the File Transfer Protocol (FTP) within the Apache architecture. It leverages Apache's flexibility to serve FTP alongside HTTP and HTTPS from the same server instance. mod_ftp supports key FTP features like SSL/TLS encryption, authentication, dynamic content, and logging while integrating with the Apache ecosystem. The document provides an overview of mod_ftp's capabilities and includes a sample configuration.
An overview of the HTTP protocol showing the protocol basics such as protocol versions, messages, headers, status codes, connection management, cookies and more.
But it still remains an overview without in-depth information. Also some key aspects are left out (because of limited time) such as authentication, content negotiation, robots, web architecture etc..
FTP is a standard protocol for transferring files that suffers from latency and packet loss issues inherent in using TCP. These problems can be solved by using file transfer acceleration techniques that switch from TCP to UDP, eliminating the effects of latency. UDP allows packets to be received out of order and does not stall if packets are dropped, improving throughput. While UDP provides the data channel, error-correcting commands are sent over a separate TCP channel to ensure reliability. This approach can significantly increase transfer speeds compared to standard FTP.
The document discusses various applications in the application layer of the Internet protocol stack, including the Domain Name System (DNS), electronic mail, the World Wide Web, streaming audio and video, and content delivery. It provides details on DNS, describing how domain names are organized hierarchically and mapped to IP addresses, and how name servers function to look up domain names. It also gives overviews of electronic mail/email, noting its widespread use both personally and for business, and the problem of spam.
Slides supporting the "Computer Networking: Principles, Protocols and Practice" ebook. The slides can be freely reused to teach an undergraduate computer networking class using the open-source ebook.
[Advantech] ADAM-3600 open vpn setting Tutorial step by step Ming-Hung Hseih
This is tutorial how to configure VPN client on IOT gateway ADAM-3600.
•Build up OpenVPN server/client
•ADAM-3600 OpenVPN setting
•ADAM-3600 OpenVPN : 3G + DDNS + public dynamic IP
SIP is a signaling protocol used to establish multimedia sessions over IP networks. It allows clients to discover each other and establish communication sessions for voice, video, or other multimedia applications. The document provides an introduction to key SIP concepts including logical entities, request/response messages, basic call flows, and the SDP protocol for negotiating media parameters. It also describes how Wireshark can be used as a development tool to analyze SIP signaling packets.
This document provides an overview of network protocols and the TCP/IP model. It describes the purpose of network protocols and the layered architecture of TCP/IP, with protocols operating at different layers to enable communication. The layers include the network access, internet, transport and application layers. Key protocols discussed include IP, ARP, ICMP, TCP and UDP, with explanations of their functions in routing packets, resolving addresses, error checking, and reliable vs. connectionless delivery.
HTTP is the foundation of data communication for the World Wide Web. It is a protocol for transferring various forms of data between a client and server. HTTP works by establishing a TCP connection between a client and server, through which HTTP request and response messages are exchanged. These messages include request methods like GET and POST, as well as response status codes like 200 for success and 404 for not found. HTTP is a stateless protocol, but cookies and caching allow servers to identify users and reduce response times.
The document discusses routing protocols in IP networks and interdomain routing. It provides an overview of IPv6 neighbor discovery, routing protocols RIP and OSPF, and interdomain routing with BGP. Key concepts covered include how routers discover each other on the local link, distance vector and link-state routing, using areas in OSPF, and the path vector exchange in BGP to choose optimal routes between autonomous systems.
This document discusses WiFi networks for high school classrooms. It begins by explaining what WiFi is and how it works to connect wireless devices to the internet through access points. It then discusses the benefits of implementing a WiFi network in a high school, such as enabling data sharing, internet access for research, and use of educational tools. The document outlines 8 steps for integrating a WiFi network, including identifying users, defining coverage areas, planning network layout and installing access points. Potential problems that could arise are also addressed, such as ensuring adequate coverage, capacity and security of the network.
This document discusses several common computer network protocols: CIDR for routing IP addresses more efficiently; NAT for sharing public IP addresses among private networks; ICMP for error detection; ARP for mapping IP addresses to MAC addresses; RARP and BOOTP as predecessors to DHCP for dynamically assigning private IP addresses; and DHCP, the current standard dynamic host configuration protocol.
Wireshark is a network protocol analyzer that intercepts and logs traffic passing over the network. It captures packets, decodes and analyzes their contents. Wireshark can be used for troubleshooting network problems, analyzing network performance, network intrusion detection, and analyzing application operations. It is a free and open-source packet analyzer that runs on Linux, macOS, and Windows.
This document provides an overview and introduction to a course on Internetworking with TCP/IP. It outlines the topics that will be covered, including terminology, concepts, protocols, architecture, and applications. It also discusses the history and development of TCP/IP, the organizations involved, and how protocol specifications are documented.
HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files between clients and servers on the World Wide Web. Communication occurs through HTTP requests from clients to servers and HTTP responses from servers to clients. A typical request/response cycle involves a browser requesting an HTML page from a server, which returns the page, and then the browser requesting and receiving additional files like stylesheets, images, and JavaScript code referenced in the HTML. An example is provided of an HTTP request from a browser to a server for a youtube.html page and the corresponding response.
The document discusses considerations for supporting legacy analogue devices in a Unified Communications project using Microsoft Lync. It describes three options for faxing - bypassing Lync, fax hairpinning within Lync, or faxing via an SBC and SIP trunk. It also provides details on configuring an analogue gateway and extensions in Lync topology builder and Active Directory to integrate analogue devices into the UC system.
Web Server Technologies I: HTTP & Getting StartedPort80 Software
Introduction to HTTP: TCP/IP and application layer protocols, URLs, resources and MIME Types, HTTP request/response cycle and proxies. Setup and deployment: Planning Web server & site deployments, Site structure and basic server configuration, Managing users and hosts.
PLNOG 9: Ivan Pepelnjak - OpenFlow and SDN: hype, useful tools or panacea?PROIDEA
This document discusses OpenFlow and Software Defined Networking (SDN). It begins with an introduction of the author, Ivan Pepelnjak, and his background. It then reviews what OpenFlow is, including separating the control and data planes and using OpenFlow as a protocol to download forwarding tables to switches. The document discusses some OpenFlow use cases like topology discovery. It also addresses questions around whether OpenFlow will replace existing routing protocols. Overall, the document provides an overview of OpenFlow and SDN, discussing concepts, use cases, and debates around the technology.
The document provides information on the TCP/IP protocol suite including:
- TCP/IP has 4 layers (Application, Transport, Network, Data Link) compared to OSI's 7 layers.
- Common application layer protocols include FTP, Telnet, SMTP, HTTP.
- Transport layer protocols are TCP and UDP which provide reliable and unreliable data transmission.
- Network layer protocols like IP, ARP, and ICMP handle routing and addressing.
- Layers communicate through encapsulation where each layer adds its own header to protocol data units.
TCPLS closely integrates TCP and TLS by using new TLS record types to carry TCP control plane information. This allows TCP options and control data to be encrypted and authenticated within TLS records. TCPLS provides benefits like securing Multipath TCP connections, enabling stronger TCP Fast Open, providing more space for TCP options, allowing true TCP keepalives, securely releasing TCP sessions, supporting Happy Eyeballs, and enabling connection migration. The integrated TCPLS protocol could improve privacy, security and functionality compared to treating TCP and TLS as separate and independent protocols.
Keynote given at DRCN2018, shows that innovation is back in the transport and network layer with a description of Multipath TCP, QUIC and IPv6 Segment Routing.
mod_ftp is a module for Apache HTTP Server that implements the File Transfer Protocol (FTP) within the Apache architecture. It leverages Apache's flexibility to serve FTP alongside HTTP and HTTPS from the same server instance. mod_ftp supports key FTP features like SSL/TLS encryption, authentication, dynamic content, and logging while integrating with the Apache ecosystem. The document provides an overview of mod_ftp's capabilities and includes a sample configuration.
An overview of the HTTP protocol showing the protocol basics such as protocol versions, messages, headers, status codes, connection management, cookies and more.
But it still remains an overview without in-depth information. Also some key aspects are left out (because of limited time) such as authentication, content negotiation, robots, web architecture etc..
FTP is a standard protocol for transferring files that suffers from latency and packet loss issues inherent in using TCP. These problems can be solved by using file transfer acceleration techniques that switch from TCP to UDP, eliminating the effects of latency. UDP allows packets to be received out of order and does not stall if packets are dropped, improving throughput. While UDP provides the data channel, error-correcting commands are sent over a separate TCP channel to ensure reliability. This approach can significantly increase transfer speeds compared to standard FTP.
The document discusses various applications in the application layer of the Internet protocol stack, including the Domain Name System (DNS), electronic mail, the World Wide Web, streaming audio and video, and content delivery. It provides details on DNS, describing how domain names are organized hierarchically and mapped to IP addresses, and how name servers function to look up domain names. It also gives overviews of electronic mail/email, noting its widespread use both personally and for business, and the problem of spam.
Slides supporting the "Computer Networking: Principles, Protocols and Practice" ebook. The slides can be freely reused to teach an undergraduate computer networking class using the open-source ebook.
[Advantech] ADAM-3600 open vpn setting Tutorial step by step Ming-Hung Hseih
This is tutorial how to configure VPN client on IOT gateway ADAM-3600.
•Build up OpenVPN server/client
•ADAM-3600 OpenVPN setting
•ADAM-3600 OpenVPN : 3G + DDNS + public dynamic IP
SIP is a signaling protocol used to establish multimedia sessions over IP networks. It allows clients to discover each other and establish communication sessions for voice, video, or other multimedia applications. The document provides an introduction to key SIP concepts including logical entities, request/response messages, basic call flows, and the SDP protocol for negotiating media parameters. It also describes how Wireshark can be used as a development tool to analyze SIP signaling packets.
This document provides an overview of network protocols and the TCP/IP model. It describes the purpose of network protocols and the layered architecture of TCP/IP, with protocols operating at different layers to enable communication. The layers include the network access, internet, transport and application layers. Key protocols discussed include IP, ARP, ICMP, TCP and UDP, with explanations of their functions in routing packets, resolving addresses, error checking, and reliable vs. connectionless delivery.
HTTP is the foundation of data communication for the World Wide Web. It is a protocol for transferring various forms of data between a client and server. HTTP works by establishing a TCP connection between a client and server, through which HTTP request and response messages are exchanged. These messages include request methods like GET and POST, as well as response status codes like 200 for success and 404 for not found. HTTP is a stateless protocol, but cookies and caching allow servers to identify users and reduce response times.
The document discusses routing protocols in IP networks and interdomain routing. It provides an overview of IPv6 neighbor discovery, routing protocols RIP and OSPF, and interdomain routing with BGP. Key concepts covered include how routers discover each other on the local link, distance vector and link-state routing, using areas in OSPF, and the path vector exchange in BGP to choose optimal routes between autonomous systems.
This document discusses WiFi networks for high school classrooms. It begins by explaining what WiFi is and how it works to connect wireless devices to the internet through access points. It then discusses the benefits of implementing a WiFi network in a high school, such as enabling data sharing, internet access for research, and use of educational tools. The document outlines 8 steps for integrating a WiFi network, including identifying users, defining coverage areas, planning network layout and installing access points. Potential problems that could arise are also addressed, such as ensuring adequate coverage, capacity and security of the network.
This document discusses several common computer network protocols: CIDR for routing IP addresses more efficiently; NAT for sharing public IP addresses among private networks; ICMP for error detection; ARP for mapping IP addresses to MAC addresses; RARP and BOOTP as predecessors to DHCP for dynamically assigning private IP addresses; and DHCP, the current standard dynamic host configuration protocol.
This document provides an overview of topics related to the internet and computer programming. It discusses the internet and types of connectivity like analog modems, DSL, and wireless. It describes the OSI model and protocols like email, SMTP, POP3, DNS, and FTP. It also covers intranets and extranets. Other topics include the world wide web, HTML, and search engines. Presentation slides are included on each of these topics with details on definitions, components, benefits, and limitations.
The document discusses firewall fundamentals, including:
- Firewalls control network traffic flow between networks with different security levels. They authenticate access, manage traffic, and protect resources.
- Firewalls can be software, appliances, or integrated into devices. They operate at OSI layers 2-7 and deny or allow access based on predefined rules.
- Common firewall architectures include single-box, screened host, screened subnet, DMZ, and dual firewall setups. Firewalls have limitations and cannot protect against all internal/external threats.
IPv4 and IPv6 are internet protocols that assign unique numerical addresses to devices to enable communication over the internet. IPv4 is the current standard but is running out of available addresses, while IPv6 utilizes a 128-bit addressing system providing over 340 undecillion available addresses to solve this problem long-term. A transition to IPv6 is underway but will take time and changes to software and infrastructure to fully implement the new standard.
The document provides an overview of key concepts for understanding firewalls. It discusses three basic types of firewalls: packet filters, application-level gateways, and stateful inspection firewalls. It also describes how firewalls work by processing packets at different locations including the network interface card, kernel, and application levels using techniques like packet filtering, proxy applications, and user authentication.
TCP/IP is a set of communication protocols used to connect devices on the internet and other networks. It has two main protocols - TCP for reliable transmission of data between devices, and IP for addressing devices and routing packets across networks. TCP/IP uses ports to allow multiple applications to run simultaneously on a single device. Routers use IP addressing and routing tables to determine the best path for sending packets between devices on different networks.
A firewall is a device that controls what gets in and comes out of our network. The firewall is placed between an organization network and the outside world.
The document discusses the Domain Name System (DNS), which translates domain names to IP addresses and vice versa. It describes the hierarchical structure of DNS with zones, resource records, and name servers. Primary and secondary name servers maintain authoritative data for zones, while caching name servers store previously looked up data to improve performance. The domain name resolution process involves queries to authoritative and caching name servers to map names to addresses.
The document discusses the need for and history of the Domain Name System (DNS). It explains that DNS was created to map human-friendly domain names to IP addresses and vice versa. Originally, a single host file contained all name-IP mappings but this became infeasible as the internet grew. DNS addresses this by hierarchically dividing the name space and distributing the mappings across multiple name servers. It uses a tree structure with domains like .com, .edu at the top level and subdomains below. DNS servers are authoritative for different zones and work together to resolve queries through either recursive or iterative queries.
SMTP is the standard protocol for sending email over the Internet. It defines the message format and how messages are transferred between mail servers. When a client wants to send a message, it establishes a connection to an SMTP server and issues commands like MAIL, RCPT, and DATA to specify the sender, recipients, and transmit the message content. While simple to implement, basic SMTP has limitations like lacking authentication that allow issues like spam. Extensions to SMTP like ESMTP aim to address such problems.
Talk by Jonathan Oxer at Linux Users Victoria in April 2007 about how DNS works. Covers authoritative and recursive DNS, delegation, and attack vectors including cache poisoning and DNS forgery. More information at http://jon.oxer.com.au/talks/id/66
The TCP/IP model has four layers: Application layer, Transport layer, Internet layer, and Network Access layer. The Application layer contains protocols that provide services to users like web browsing, email, and file transfers. The Transport layer deals with manipulating data and preparing it for delivery through the network using protocols like TCP and UDP. The Internet layer determines routing and addresses using IP addressing and routing protocols. The Network Access layer is responsible for transmitting bits and bytes across physical network connections using devices like hubs, switches, and network interface cards.
This document provides an overview of the Domain Name System (DNS). It discusses what DNS is, why names are used instead of IP addresses, and the history and development of DNS. It describes the hierarchical name space and domain system. It also explains different DNS record types like A, CNAME, MX, and NS records. The document discusses recursive and iterative queries, legal users of domains, and security issues with the traditional DNS system. It provides an overview of how DNSSEC aims to address some of these security issues through digital signing of DNS records.
FTP (File Transfer Protocol) allows users to transfer files between computers over the Internet. It uses separate channels for control commands and data transfer. Common FTP clients include FileZilla and programs built into web browsers. FTP operates using a client-server model with different processes for control and data transfer between client and server computers.
The document discusses the Domain Name System (DNS) and its components. It explains what DNS is, how it works to translate domain names to IP addresses, the different record types used in DNS like A, NS, MX records. It describes DNS name servers, resolvers, zones and namespaces. It provides examples of DNS configuration files for both master and slave name servers as well as sample zone files mapping names to IP addresses.
Overview of the Domain Name System (DNS).
In the early days of the Internet, hosts had a fixed IP address.
Reaching a host required to know its numeric IP address.
With the growing number of hosts this scheme became quickly awkward and difficult to use.
DNS was introduced to give hosts human readable names that would be translated into a numeric IP addresses on the fly when a requesting host tried to reach another host.
To facilitate a distributed administration of the domain names, a hierarchic scheme was introduced where responsibility to manage domain names is delegated to organizations which can further delegate management of sub-domains.
Due to its importance in the operation of the Internet, domain name servers are usually operated redundantly. The databases of both servers are periodically synchronized.
The document discusses the TCP/IP protocol suite and compares it to the OSI model. It describes the layers of the TCP/IP model including the physical, data link, internet, and transport layers. The transport layer uses TCP and UDP, with TCP being connection-oriented and reliable, while UDP is connectionless. The internet layer uses IP to transport datagrams independently. The OSI model has 7 layers while TCP/IP has 5 layers that do not directly correspond to the OSI layers.
This document discusses amplitude modulation (AM) as a type of modulation used to transmit information signals. Modulation involves varying a high frequency carrier signal by an information signal in order to transmit the information signal over long distances. In AM, the amplitude of the carrier signal is varied in accordance with the instantaneous amplitude of the modulating or information signal. This creates two new sideband frequencies above and below the carrier frequency equal to the modulation frequency. The carrier and sidebands together make up the modulated signal. Only a portion of the transmitted power is present in the sidebands containing the information, while the rest is wasted in the carrier.
The Internet Control Message Protocol (ICMP) is used to report issues with the delivery of IP packets. It allows devices on the network to check connectivity and diagnose routing problems. ICMP messages are transmitted as IP packets and used by ping and traceroute utilities. It supports functions like announcing network errors, congestion, and assisting troubleshooting. While providing important feedback, ICMP redirect messages can potentially direct traffic to unauthorized systems if not restricted to trusted sources.
TCP/IP is a set of communication protocols that allows devices to connect on the internet. It has two main protocols - TCP and IP. TCP ensures reliable delivery of segments through acknowledgements and retransmissions. IP handles addressing and routing of packets between networks. Common applications that use TCP/IP include HTTP, FTP, SMTP and more. It is popular due to its early development and support in operating systems like UNIX.
TCP/IP is a set of communication protocols used to connect devices on the internet and private networks. It includes the Transmission Control Protocol (TCP) and Internet Protocol (IP). TCP provides reliable data transmission and IP provides routing of packets between networks. TCP/IP was adopted by the internet and became popular due to its early development and support in UNIX. It uses port numbers and IP addresses to allow multiple applications to operate over the same network connection. Domain names are used to make IP addresses easier for humans to remember.
The Internet protocol suite, commonly known as TCP/IP, is a framework for org...MathivananP4
The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria.
TCP/IP Protocol Suite model Transmission Control Protocol27230106
TCP/IP is a set of protocols developed to allow cooperating computers to share resources across a network
TCP stands for “Transmission Control Protocol”
IP stands for “Internet Protocol”
They are Transport layer and Network layer protocols respectively of the protocol suite
The most well known network that adopted TCP/IP is Internet – the biggest WAN in the world
The document discusses the TCP/IP protocol suite including the layers, protocols, addressing, and routing. It describes the layers of TCP/IP including application, transport, internet, and link layers. Examples are provided of protocols at each layer like SMTP, TCP, IP, and ARP. Network addressing, subnets, port numbers, and routing between routers is also covered at a high level.
This document provides an overview of the TCP/IP protocol stack. It discusses the four layers of TCP/IP - network interface, internet, transport and application layer - and how they relate to the seven-layer OSI model. Key protocols at each layer like IP, TCP, UDP, HTTP, and FTP are explained. The roles of ports, port scanning, and APIs are also summarized.
This document provides an overview of the TCP/IP protocol stack. It discusses the four layers of TCP/IP - network interface, internet, transport and application layer - and how they relate to the seven-layer OSI model. Key protocols of each TCP/IP layer like IP, TCP, UDP, HTTP, FTP, SMTP are explained along with their functions. Other topics covered include ports, port scanning, and Windows sockets API.
TCP/IP is a set of protocols that allows computers to communicate over a network. It includes IP for routing packets between hosts and TCP and UDP for transporting data between processes. TCP provides reliable, connection-oriented delivery while UDP provides simpler, connectionless delivery. The protocols originated in the 1970s from research funded by the US military and became the standard for internet communication, allowing different computer platforms to interconnect globally through a common protocol.
UDP is a transport layer protocol that provides an unreliable datagram service. It is positioned directly above IP in the TCP/IP protocol stack. UDP packets contain a header with source and destination port numbers as well as length fields, but do not establish connections, provide sequencing, or guarantee delivery like TCP. Well-known ports are assigned to common UDP applications like DNS, time synchronization, and trivial file transfer.
The document discusses the OSI 7-layer model and TCP/IP networking stack. It describes the purpose and key characteristics of each layer, including the physical, data link, network, transport, and application layers. Each layer uses protocol data units and passes information to other layers using predefined services. Well-known ports are assigned at the transport layer to indicate the destination for incoming data traffic.
The document discusses computer networks and network protocols. It begins with an introduction to network protocols and the Internet protocols. It then provides definitions and explanations of communication protocols, including addressing, transmission modes, and error detection/recovery techniques. It lists and describes common network protocols like TCP/IP, routing protocols, FTP, SMTP, and more. It also discusses the OSI model layers, TCP/IP protocol suite, data encapsulation, protocol data units, protocol assignments to layers, and addresses at each layer.
The document provides an overview of TCP/IP, including its origins, standards groups, models, protocols, and analysis. Key points covered include TCP/IP's design goals of withstanding disruption and enabling interoperability, the transition from IPv4 to IPv6 to address limited addresses, and how protocol analyzers work to capture and decode network packets for troubleshooting.
This document contains 12 questions and answers about transport layer protocols like UDP and TCP. It discusses topics like the maximum size of UDP and TCP packets, examples of when UDP is preferable to TCP, how port numbers allow processes to be uniquely identified, and why TCP must handle out-of-order data even though IP handles fragmentation and reassembly. The document provides technical details about transport layer protocols in response to questions about their specifications, capabilities, and how they address reliability compared to the underlying IP layer.
This document discusses various topics related to computer networking including protocols, sockets, IP addresses, URLs, reading web page source code, downloading files from the internet, TCP/IP and UDP servers and clients, file servers and clients, two-way communication between servers and clients, and sending simple emails. It provides information on networking hardware and software, protocols like TCP/IP and UDP, socket programming, parsing URLs, creating servers and clients, and sending/receiving data over networks.
The document discusses the four levels of addressing used in TCP/IP:
1. Physical address - identifies network interfaces or devices
2. Logical address - IP addresses that identify devices on the network
3. Port address - identifies applications/processes on devices using port numbers
4. Application-specific address - some applications use their own addressing schemes above the port level.
This document provides a primer on browser networking. It begins with an introduction and overview of the target audience. The content includes an explanation of the TCP/IP network model and layers. Key aspects of TCP such as the three-way handshake, flow control, slow start, and head of line blocking are described. The history of web protocols like HTTP 0.9, HTTP 1.0, HTTP 1.1, and developments like HTTP 2.0, SPDY, and QUIC are summarized. Examples and diagrams are provided to illustrate concepts. Resources for further reading are included.
This document provides an overview of key topics in data communications and networking protocols. It defines what a protocol is, describing the key elements of syntax, semantics, and timing. It also discusses layered protocol architectures like TCP/IP and the OSI model. Common protocol functions are explained, such as encapsulation, fragmentation and reassembly, and addressing. Application layer protocols for the internet like HTTP, SMTP, and TCP sockets are covered. The document uses examples to illustrate client-server and peer-to-peer network architectures as well as socket programming.
Get into Networking by Clearing Comptia Network+ Testcertblaster
The document summarizes key aspects of the OSI model, including:
1) The OSI model breaks network communication into 7 layers (physical, data link, network, transport, session, presentation, application) to standardize network components and allow different hardware/software to communicate.
2) Each layer has a specific role like physical addressing (data link), logical addressing (network), and ensuring reliable data transmission (transport).
3) The TCP/IP model is similar to OSI but combines some layers. It uses IP addresses, TCP/UDP, and port numbers to route packets between applications running on devices.
4) Common network devices operate at different layers, with cables and wireless access points at layer 1
TCP and UDP are transport layer protocols used for data transfer in the OSI model. TCP is connection-oriented, requiring a three-way handshake to establish a connection that maintains data integrity. It guarantees data will reach its destination without duplication but is slower than UDP. UDP is connectionless and used for applications requiring fast transmission like video calls, but does not ensure packet delivery and order. Both protocols add headers to packets with TCP focused on reliability and UDP on speed.
Skybuffer AI: Advanced Conversational and Generative AI Solution on SAP Busin...Tatiana Kojar
Skybuffer AI, built on the robust SAP Business Technology Platform (SAP BTP), is the latest and most advanced version of our AI development, reaffirming our commitment to delivering top-tier AI solutions. Skybuffer AI harnesses all the innovative capabilities of the SAP BTP in the AI domain, from Conversational AI to cutting-edge Generative AI and Retrieval-Augmented Generation (RAG). It also helps SAP customers safeguard their investments into SAP Conversational AI and ensure a seamless, one-click transition to SAP Business AI.
With Skybuffer AI, various AI models can be integrated into a single communication channel such as Microsoft Teams. This integration empowers business users with insights drawn from SAP backend systems, enterprise documents, and the expansive knowledge of Generative AI. And the best part of it is that it is all managed through our intuitive no-code Action Server interface, requiring no extensive coding knowledge and making the advanced AI accessible to more users.
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-und-domino-lizenzkostenreduzierung-in-der-welt-von-dlau/
DLAU und die Lizenzen nach dem CCB- und CCX-Modell sind für viele in der HCL-Community seit letztem Jahr ein heißes Thema. Als Notes- oder Domino-Kunde haben Sie vielleicht mit unerwartet hohen Benutzerzahlen und Lizenzgebühren zu kämpfen. Sie fragen sich vielleicht, wie diese neue Art der Lizenzierung funktioniert und welchen Nutzen sie Ihnen bringt. Vor allem wollen Sie sicherlich Ihr Budget einhalten und Kosten sparen, wo immer möglich. Das verstehen wir und wir möchten Ihnen dabei helfen!
Wir erklären Ihnen, wie Sie häufige Konfigurationsprobleme lösen können, die dazu führen können, dass mehr Benutzer gezählt werden als nötig, und wie Sie überflüssige oder ungenutzte Konten identifizieren und entfernen können, um Geld zu sparen. Es gibt auch einige Ansätze, die zu unnötigen Ausgaben führen können, z. B. wenn ein Personendokument anstelle eines Mail-Ins für geteilte Mailboxen verwendet wird. Wir zeigen Ihnen solche Fälle und deren Lösungen. Und natürlich erklären wir Ihnen das neue Lizenzmodell.
Nehmen Sie an diesem Webinar teil, bei dem HCL-Ambassador Marc Thomas und Gastredner Franz Walder Ihnen diese neue Welt näherbringen. Es vermittelt Ihnen die Tools und das Know-how, um den Überblick zu bewahren. Sie werden in der Lage sein, Ihre Kosten durch eine optimierte Domino-Konfiguration zu reduzieren und auch in Zukunft gering zu halten.
Diese Themen werden behandelt
- Reduzierung der Lizenzkosten durch Auffinden und Beheben von Fehlkonfigurationen und überflüssigen Konten
- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
- Tipps für häufige Problembereiche, wie z. B. Team-Postfächer, Funktions-/Testbenutzer usw.
- Praxisbeispiele und Best Practices zum sofortigen Umsetzen
Taking AI to the Next Level in Manufacturing.pdfssuserfac0301
Read Taking AI to the Next Level in Manufacturing to gain insights on AI adoption in the manufacturing industry, such as:
1. How quickly AI is being implemented in manufacturing.
2. Which barriers stand in the way of AI adoption.
3. How data quality and governance form the backbone of AI.
4. Organizational processes and structures that may inhibit effective AI adoption.
6. Ideas and approaches to help build your organization's AI strategy.
Dive into the realm of operating systems (OS) with Pravash Chandra Das, a seasoned Digital Forensic Analyst, as your guide. 🚀 This comprehensive presentation illuminates the core concepts, types, and evolution of OS, essential for understanding modern computing landscapes.
Beginning with the foundational definition, Das clarifies the pivotal role of OS as system software orchestrating hardware resources, software applications, and user interactions. Through succinct descriptions, he delineates the diverse types of OS, from single-user, single-task environments like early MS-DOS iterations, to multi-user, multi-tasking systems exemplified by modern Linux distributions.
Crucial components like the kernel and shell are dissected, highlighting their indispensable functions in resource management and user interface interaction. Das elucidates how the kernel acts as the central nervous system, orchestrating process scheduling, memory allocation, and device management. Meanwhile, the shell serves as the gateway for user commands, bridging the gap between human input and machine execution. 💻
The narrative then shifts to a captivating exploration of prominent desktop OSs, Windows, macOS, and Linux. Windows, with its globally ubiquitous presence and user-friendly interface, emerges as a cornerstone in personal computing history. macOS, lauded for its sleek design and seamless integration with Apple's ecosystem, stands as a beacon of stability and creativity. Linux, an open-source marvel, offers unparalleled flexibility and security, revolutionizing the computing landscape. 🖥️
Moving to the realm of mobile devices, Das unravels the dominance of Android and iOS. Android's open-source ethos fosters a vibrant ecosystem of customization and innovation, while iOS boasts a seamless user experience and robust security infrastructure. Meanwhile, discontinued platforms like Symbian and Palm OS evoke nostalgia for their pioneering roles in the smartphone revolution.
The journey concludes with a reflection on the ever-evolving landscape of OS, underscored by the emergence of real-time operating systems (RTOS) and the persistent quest for innovation and efficiency. As technology continues to shape our world, understanding the foundations and evolution of operating systems remains paramount. Join Pravash Chandra Das on this illuminating journey through the heart of computing. 🌟
Salesforce Integration for Bonterra Impact Management (fka Social Solutions A...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on integration of Salesforce with Bonterra Impact Management.
Interested in deploying an integration with Salesforce for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
5th LF Energy Power Grid Model Meet-up SlidesDanBrown980551
5th Power Grid Model Meet-up
It is with great pleasure that we extend to you an invitation to the 5th Power Grid Model Meet-up, scheduled for 6th June 2024. This event will adopt a hybrid format, allowing participants to join us either through an online Mircosoft Teams session or in person at TU/e located at Den Dolech 2, Eindhoven, Netherlands. The meet-up will be hosted by Eindhoven University of Technology (TU/e), a research university specializing in engineering science & technology.
Power Grid Model
The global energy transition is placing new and unprecedented demands on Distribution System Operators (DSOs). Alongside upgrades to grid capacity, processes such as digitization, capacity optimization, and congestion management are becoming vital for delivering reliable services.
Power Grid Model is an open source project from Linux Foundation Energy and provides a calculation engine that is increasingly essential for DSOs. It offers a standards-based foundation enabling real-time power systems analysis, simulations of electrical power grids, and sophisticated what-if analysis. In addition, it enables in-depth studies and analysis of the electrical power grid’s behavior and performance. This comprehensive model incorporates essential factors such as power generation capacity, electrical losses, voltage levels, power flows, and system stability.
Power Grid Model is currently being applied in a wide variety of use cases, including grid planning, expansion, reliability, and congestion studies. It can also help in analyzing the impact of renewable energy integration, assessing the effects of disturbances or faults, and developing strategies for grid control and optimization.
What to expect
For the upcoming meetup we are organizing, we have an exciting lineup of activities planned:
-Insightful presentations covering two practical applications of the Power Grid Model.
-An update on the latest advancements in Power Grid -Model technology during the first and second quarters of 2024.
-An interactive brainstorming session to discuss and propose new feature requests.
-An opportunity to connect with fellow Power Grid Model enthusiasts and users.
Fueling AI with Great Data with Airbyte WebinarZilliz
This talk will focus on how to collect data from a variety of sources, leveraging this data for RAG and other GenAI use cases, and finally charting your course to productionalization.
Introduction of Cybersecurity with OSS at Code Europe 2024Hiroshi SHIBATA
I develop the Ruby programming language, RubyGems, and Bundler, which are package managers for Ruby. Today, I will introduce how to enhance the security of your application using open-source software (OSS) examples from Ruby and RubyGems.
The first topic is CVE (Common Vulnerabilities and Exposures). I have published CVEs many times. But what exactly is a CVE? I'll provide a basic understanding of CVEs and explain how to detect and handle vulnerabilities in OSS.
Next, let's discuss package managers. Package managers play a critical role in the OSS ecosystem. I'll explain how to manage library dependencies in your application.
I'll share insights into how the Ruby and RubyGems core team works to keep our ecosystem safe. By the end of this talk, you'll have a better understanding of how to safeguard your code.
Trusted Execution Environment for Decentralized Process MiningLucaBarbaro3
Presentation of the paper "Trusted Execution Environment for Decentralized Process Mining" given during the CAiSE 2024 Conference in Cyprus on June 7, 2024.
Digital Marketing Trends in 2024 | Guide for Staying AheadWask
https://www.wask.co/ebooks/digital-marketing-trends-in-2024
Feeling lost in the digital marketing whirlwind of 2024? Technology is changing, consumer habits are evolving, and staying ahead of the curve feels like a never-ending pursuit. This e-book is your compass. Dive into actionable insights to handle the complexities of modern marketing. From hyper-personalization to the power of user-generated content, learn how to build long-term relationships with your audience and unlock the secrets to success in the ever-shifting digital landscape.
Skybuffer SAM4U tool for SAP license adoptionTatiana Kojar
Manage and optimize your license adoption and consumption with SAM4U, an SAP free customer software asset management tool.
SAM4U, an SAP complimentary software asset management tool for customers, delivers a detailed and well-structured overview of license inventory and usage with a user-friendly interface. We offer a hosted, cost-effective, and performance-optimized SAM4U setup in the Skybuffer Cloud environment. You retain ownership of the system and data, while we manage the ABAP 7.58 infrastructure, ensuring fixed Total Cost of Ownership (TCO) and exceptional services through the SAP Fiori interface.
Programming Foundation Models with DSPy - Meetup SlidesZilliz
Prompting language models is hard, while programming language models is easy. In this talk, I will discuss the state-of-the-art framework DSPy for programming foundation models with its powerful optimizers and runtime constraint system.
System Design Case Study: Building a Scalable E-Commerce Platform - Hiike
tcpip
1. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
FTP, SMTP, Telnet,
HTTP,…
TCP, UDP
IP, ARP, ICMP
Network Interface
9. TCP/IP
1
Reference: Charles L. Hedrick, “Introduction to the Internet Protocols”, Rutgers
University, http://oac3.hsc.uth.tmc.edu/staff/snewton/tcp-tutorial/
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
A. What is TCP/IP?
• TCP/IP is a set of protocols developed to allow
cooperating computers to share resources across a
network
• TCP stands for “Transmission Control Protocol”
• IP stands for “Internet Protocol”
• They are Transport layer and Network layer
protocols respectively of the protocol suite
• The most well known network that adopted
TCP/IP is Internet – the biggest WAN in the world
2
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
What is a protocol?
• A protocol is a collection of rules and procedures
for two computers to exchange information
• Protocol also defines the format of data that is
being exchanged
3
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Why TCP/IP is so popular?
• TCP/IP was developed very early
• Technologies were widely discussed and circulated
in documents called “Request for Comments”
(RFC) – free of charge
• Supported by UNIX operating system
4
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
TCP/IP Model
• Because TCP/IP was developed earlier than the
OSI 7-layer mode, it does not have 7 layers but
only 4 layers
TCP/IP Protocol Suite
FTP, SMTP, Telnet,
HTTP,…
TCP, UDP
IP, ARP, ICMP
Network Interface
5
OSI 7-layer
6. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• Application layer protocols define the rules when
implementing specific network applications
• Rely on the underlying layers to provide accurate
and efficient data delivery
• Typical protocols:
6
• FTP – File Transfer Protocol
• For file transfer
• Telnet – Remote terminal protocol
• For remote login on any other computer on the
network
• SMTP – Simple Mail Transfer Protocol
• For mail transfer
• HTTP – Hypertext Transfer Protocol
• For Web browsing
7. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• TCP/IP is built on “connectionless” technology,
each datagram finds its own way to its destination
• Transport Layer protocols define the rules of
• Dividing a chunk of data into segments
• Reassemble segments into the original chunk
• Typical protocols:
7
• TCP – Transmission Control Protocol
• Provide further the functions such as reordering
and data resend
• UDP – User Datagram Service
• Use when the message to be sent fit exactly into a
datagram
• Use also when a more simplified data format is
required
8. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• Network layer protocols define the rules of how to
find the routes for a packet to the destination
• It only gives best effort delivery. Packets can be
delayed, corrupted, lost, duplicated, out-of-order
• Typical protocols:
• IP – Internet Protocol
• Provide packet delivery
• ARP – Address Resolution Protocol
• Define the procedures of network address / MAC
address translation
• ICMP – Internet Control Message Protocol
• Define the procedures of error message transfer
8
10. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
B. Example: SMTP
SMTP Server
Client
SMTP
Virtual
TCP
IP, ARP, ICMP
Network Interface
10
SMTP
TCP
Actual
IP, ARP, ICMP
Network Interface
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• The underlying layers have guaranteed accurate
data delivery
• We need to make a lot agreements with the server
in application layer before sending mail
11
1. Agree on how data is represented
• Binary or ASCII
2. Ensure the right recipient
• There may be 1000 users served by the server
3. Ensure the client has the right to send mail
• Some clients are not welcome
4. How to tell the server it is the end of the message
• All mail looks the same
:
12. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• Example: SMTP
The following mail is to be sent:
Date: Fri, 18 Jan 02 13:26:31 EDT
From: enpklun@polyu.edu.hk
To: tchsun@eee.hku.hk
Subject: meeting
Let’s get together Monday at 1pm.
12
13. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Client
SMTP Server
access port 25 of server
220 eee.hku.hk SMTP Service
at 20 Jan 02 05:17:18 EDT
HELO polyu.edu.hk
250 eee.hku.hk – Hello,
polyu.edu.hk
MAIL From:
<enpklun@polyu.edu.hk>
250 MAIL accepted
13
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Client
SMTP Server
RCPT To:<tchsun@eee.hku.hk>
250 Recipient accepted
DATA
354 Start mail input;
end with .
Date: Fri, 18 Jan 02 13:26:31 EDT
From: enpklun@polyu.edu.hk
To: tchsun@eee.hku.hk
Subject: meeting
14
Let’s get together Monday at 1pm.
.
15. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• The agreement made in the SMTP protocol
• All messages use normal text
• All ASCII characters
• The responses all begin with numbers
• To indicate the status when receiving the command
• Some words are reserved words
• HELO, MAIL, RCPT…
• Mail ends with a line that contains only a period
• The information passed with the SMTP messages
• The recipient name
• The sender name
• The mail
15
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
C. Domain Name (mentioned before)
• Every computer has a network address
• e.g. 158.132.161.99
• To access a computer, we need to specify its
network address
• Human beings are weak in memorizing numbers
• We prefer computer name or domain name
• e.g. hkpu10.polyu.edu.hk
• Need a machine on the Internet to convert name to
number
16
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Domain name hierarchy
Example:
hkpu10.polyu.edu.hk
Computer name
• The domain
within edu.hk
• One of the
educational
institutions in
H.K.
17
• The domain
within hk
• Note: edu.hk
is not the
same as edu
Root domain name
other examples:
com – commercial company
org – general organization
net – major network centre
gov – government org.
mil – militrary group
edu – education org.
18. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• An organization needs to register its domain name
• e.g. PolyU has registered its name to the domain
of edu.hk
• Once a domain name is assigned, the organization
is free to assign other names belong to its domain
• e.g. we can have
hkpu10.polyu.edu.hk
smtp.polyu.edu.hk
mail.polyu.edu.hk
18
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Client
Where is
www.yahoo.com?
Domain Name Server
(DNS) of polyu.edu.hk
usually UDP
Address of
www.yahoo.com
Where is
www.yahoo.com?
Become
client
Where is
yahoo.com?
Address of
www.Yahoo.com
Address of the
DNS of
Yahoo.com
DNS of Yahoo.com
19
DNS of com
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• Nevertheless, such a complicated procedure needs
not perform in most cases
• Client computers usually remember the answers
that it got before
• It reduces the loading to the root DNS
• To further reduce loading, there can be many root
DNS on the Internet
• e.g. there are a few “com” root DNS
20
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Transport Layer
Message
Application
Segments
Transport
Network
Network Interface
21
h M
h M
h M
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
D. TCP and UDP
TCP – Transmission Control Protocol
• TCP is a connection-oriented protocol
• Does not mean it has a physical connection between
sender and receiver
• TCP provides the function to allow a connection
virtually exists – also called virtual circuit
• TCP provides the functions:
• Dividing a chunk of data into segments
• Reassembly segments into the original chunk
• Provide further the functions such as reordering and
data resend
22
• Offering a reliable byte-stream delivery service
23. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Dividing and Reassembly
Source Port
TCP
Destination
Port
Sequence Number
Acknowledgement
Number
Message
Checksum
Message Data
23
25. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• A Typical Procedure
• Sender
• TCP divides a message into segments
• Add sequence no.
• Send the segments in sequence and wait for
acknowledgement
• If an acknowledgement for a segment is not received
for a certain period of time, resend it until an
acknowledgement is received
• Recipient
• When receiving segments, send the
acknowledgement with correct number
• Reassembly the segments back to the message
25
26. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Port Multiplexing
• A computer may perform a number of network
applications at the same time
• FTP + SMTP + HTTP, etc.
• Each computer has only one network address, how
can it serve so many applications at the same time?
⇒ by port multiplexing
FTP
Port 21
26
Network add:
158.132.161.99
SMTP
Port 25
HTTP
Port 80
27. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Well-known Port Numbers
• Some port numbers are reserved for some
purposes
•
•
•
•
Port 21: FTP – file transfer
Port 25: SMTP – mail transfer
Port 23: TELNET – remote login
Port 80: HTTP – Web access
• These port numbers are well known to all
computers in the network
• E.g. whenever a client access port 25 of the server,
it means the client needs SMTP service
27
28. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Client
SMTP port
= 1357
SMTP Server
Located by: network
address + TCP port
no.
Source Port
= 1357
Destination
Port = 25
Sequence Number
Acknowledgement
Number
Checksum
28
Message Data
SMTP port
= 25
29. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Client A
SMTP + FTP Server
Network address:
158.132.161.99
SMTP port
= 1357
Client B
29
FTP port
= 1361
SMTP port
= 25
FTP port
= 21
30. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Network Layer
Message
Application
Segments
Transport
Network
Network Interface
30
h M
h h M
h M
h h M
h M
h h M
Datagrams / Packets
31. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
E. Network Addresses and
Subnets
• A header is added to each segment in the
Network layer
3
Segment
IP
Time to
Live
Protocol
Total
Length
Header
CheckSum
Source Address
Destination Address
Segment
31
32. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• Total Length – Total length of a packet (up to
65535 bytes)
• Time to Live – How many times this packet can
be routed on the network (up to 255)
• Protocol – The transport layer protocol that
the packet belongs to
• TCP: 6
• UDP: 17
• ICMP: 1
32
• Source address – the network address of the
computer that sends the data
• Destination address – the network address of
the computer that the data is sending to
33. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• (Already mentioned)
• Each computer (host) must have a unique
network address (or IP address for TCP/IP suite)
• Each IP address is 32-bit long (four bytes)
• The four-byte address is written out as a.b.c.d
• e.g.
Byte 1
Byte 2
Byte 3
Byte 4
158
33
132
161
99
• IP addresses are hierarchical
• network I.D. and host I.D.
• Each Network I.D. on the Internet needs to be
registered to the Internet Assigned Number
Authority
34. ENG224
INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Class A – for very large network
1 bit
7 bits
24 bits
0 Net I.D.
Host I.D.
• Only 27 (63) networks can belong to this class
• Each network, there are 224 hosts or computers
• Very few class A networks in the world
• e.g. Arpanet – the earliest packet switched
WAN (started 40 years ago)
34
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Class B – for medium size network
2 bits
1 0
14 bits
Net I.D.
16 bits
Host I.D.
• 214 (16384) networks can belong to this class
• Each network, there are 216 (65536) hosts or
computers
• Polyu’s address belongs to this group
• e.g. 158.132.14.1
1001 1110
35
1000 0100
Network I.D.
0000 1110
0000 0001
Host I.D.
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Class C – for small network
3 bits
21 bits
8 bits
1 1 0
Net I.D.
Host I.D.
• 221 networks can belong to this class
• Each network, there are only 28 (256) hosts or
computers
36
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Class D – for multicast network
4 bits
1 1 1 0
28 bits
Group no.
• Packets are addressed to a multicast group
• Not often supported on Internet
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Special Addresses
38
• Host I.D. = all ‘1’s ⇒ Directed broadcast
“Broadcast to all hosts in the network or
subnetwork”, not assigned
• Host I.D. = all ‘0’s ⇒ “This network”, not
assigned
• Network I.D. = 127 is reserved for loopback and
diagnostic purposes, not assigned
• Network I.D. + Host I.D. = all ‘1’s ⇒ Limited
broadcast
“Broadcast to all hosts in the current network”,
not assigned
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Subnets
• A class B address can have 65536 hosts
• Difficult to manage
• Usually subdivide into a few small subnets
• Subnetting can also help to reduce broadcasting
traffic
158.132.1.0
Router
158.132.0.0
Total 65536 hosts
Router
158.132.2.0
158.132.3.0
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All traffic to
158.132.0.0
All traffic to
158.132.0.0
Each subnet 256 hosts
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Subnet Mask
• How does the router know which subnet a packet
should go?
• For each interface of the router, a subnet mask is
provided to redefine which part of the address is
Net ID and which part is Host ID
• Become classless addressing
A subnet mask: 255.255.255.0
1111 1111.1111 1111. 1111 1111. 0000 0000
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‘1’s Net ID
‘0’s Host ID
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
158.132.1.10
Router
E0
A packet with
destination address
158.132.1.10
S0
S1
S2
Routing Table
S0
Subnet
Mask
AND
41
S1
S2
158.132.1.0
158.132.2.0
158.132.3.0
255.255.255.0 255.255.255.0 255.255.255.0
158.132. 1. 10
255.255.255. 0
158.132. 1. 0
1001 1110.1000 0100.0000 0001.0000
1010
AND 1111 1111.1111 1111.1111 1111.0000 0000
1001 1110.1000 0100.0000 0001.0000
Advantage: easy to compute
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
F. Routing
• How a packet finds its way to a computer in a
network?
• By using Routers
• Routing is the selection of a path to guide a
packet from the source to the destination
• Criteria in selecting a path may be:
• Shortest path
• Quickest path
• Cheapest path
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Internet
router
U.S.
212.64.123.98
The red path is the
shortest path
43
Hong Kong
158.132.161.99
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
44
• Each router has a table that records the
estimated distance to all other routers
• If a router knows the entire network topology,
the shortest path can be calculated
• To achieve this, routers broadcast Link State
Advertisement to all other routers periodically
• By means of routing protocol
• Each router knows the exact topology, and
then calculates the shortest path
• In practice, it is not possible for a router to all
paths. Only the nearer ones are kept
• Hence can give wrong estimation
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Host A
158.132.148.66
Default gateway: Router C
Subnet
158.132.166.0
S0
Router A
T0
T1
T0
S1
45
S1
T1
S1 158.132.166.0 Direct
255.255.255.0
T1 160. 64. 0. 0 Forward
255.255. 0. 0
T0
S0
Router C
Routing Table
Router B T0
Routing Table
S0 160. 64.124.0 Direct
255.255.255.0
S1 160. 64.123.0 Direct
255.255.255.0
S0
Subnet
160.64.124.0
S1
Subnet
160.64.123.0
Host B
160.64.123.98
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
46
1. Host A wants to send a packet to Host B with address
160.64.123.98
2. Host A checks that 160.64.123.98 is not in the same
network
3. Send packet to default gateway (Router C)
4. Default gateway finds that it cannot provide the best
route for the packet, inform Host A to send the
packet to Router A next time
5. Router C sends the packet to Router A
6. Router A checks from the table the packet should
forward to Router B
7. Router B receives the packet and checks in its table
the packet should directly deliver to subnet
160.64.123.0
8. Host B (160.64.123.98) receives the packet
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
Data Link and
Physical Layers
Message
Application
Segments
Transport
Network
h M
h h M
h M
h M
h h M
h h M
Packets
Network Interface
h h h M
47
h h h M
Frames
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
G. Ethernet Encapsulation and
ARP
• An IP packet should be encapsulated into a
frame for transmission by data link layer
• e.g. if Ethernet (or IEEE 802.3) is used:
Preamble
Des. Add
7
1
2/6
Bytes Byte Bytes
48
Sour. Add
2/6
Bytes
Length
IP Packet
FCS
2
46 - 1500 Bytes
4
Bytes
Bytes
IEEE 802.3 Frame
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
• Only the hardware address (MAC address) is
unique to a host
• Need to convert a network address to MAC
address
Source IP =
158.132.148.66
Destination IP = 158.132.148.132
Packet
Ethernet
Packet
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Ethernet
Frame
Ethernet address = ?
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
ARP – Address Resolution Protocol
Case 1
1. Broadcast: Who has got IP address
158.132.148.132? What’s your
Ethernet address?
2. Reply: I do. My Ethernet address is
00-60-8C-41-37-52
3.
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Ethernet Frame
Ethernet address = 00-60-8C-41-37-52
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
ARP – Address Resolution Protocol
Case 2
1. Broadcast: Who has got IP address
158.132.148.132? What’s your
Ethernet address?
Router
3.
2. Reply: The IP you indicated is not in your network.
You can give the packet to me first. My MAC address
is 00-60-8C-12-34-56
Ethernet Frame
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Ethernet address = 00-60-8C-12-34-56
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INFORMATION TECHNOLOGY – Part I
9. TCP/IP
ARP Cache
• Will have a heavy traffic if so many ARP
broadcast messages are generated
• Each host will have a cache to store the
mappings (from IP to MAC address) that were
obtained before
IP Address
158.132.148.80
00-60-8C-27-35-9A
158.132.148.28
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MAC Address
02-60-8C-1A-37-49
• An entry will only be kept in the cache for a
limited amount of time (say, 2 minutes)