Lecture 6: TCP/IP Networking By: Adal Alashban Edited by: Sara Alhajjam

Sockets - Sockets, or ports, are a very low level software construct, that allows computers to talk to one another. When you send information from one computer to another, you send it to a socket port on the receiving computer. A socket is one endpoint of a two-way communication link between two programs running on the network. A socket is bound to a port number so that the TCP layer can identify the application that data is destined to be sent to.

Created By Dr.Najla AlNabhan edited by Maysoon AlDuwais Sockets Common port numbers are 80 (for web pages), 23 (for telnet) and 25 and 110 (for mail). Port numbers above 1024 are available for other kinds of communication between our programs. Created By Dr.Najla AlNabhan edited by Maysoon AlDuwais

Protocols - In order for computers to communicate with one another, they must agree on a set of rules for who says what, when they say it, and what format they say it in this set of rules is a protocol. - Different programs can use different protocols. - Protocols may be in ASCII (characters) or in binary. - Some common protocols are HTTP (for web pages), FTP (for file transfer), and SMTP (Simple Mail Transfer Protocol).

TCP/IP (Transmission Control Protocol/Internet Protocol) - The Internet (and most other computer networks) are connected through TCP/IP networks. - It is a suite of communication protocols used to interconnect network devices on the internet. TCP/IP can also be used as a communications protocol in a private network (an intranet or an extranet).

TCP/IP (Transmission Control Protocol/Internet Protocol) - TCP/IP is actually a combination of two protocols: IP, Internet Protocol, is used to move packets (chunks) of data from one place to another. Places are specified by IP addresses: four single-byte (0..255) numbers separated by periods, Example: 192.168.1.1 TCP, Transmission Control Protocol, ensures that all necessary packets are present, and puts them together in the correct order.

TCP/IP Protocol Architecture - No official model but a working one. Physical layer Network access layer Internet layer Host to host or transport layer Application layer

1. Physical Layer Physical interface between data transmission device (e.g. computer) and transmission medium (e.g. electrical cable, an optical fiber cable) or network Characteristics of transmission medium It defines the network topology as bus, mesh, or ring The physical layer is never concerned with protocols or other such higher-layer items. etc.

2. Network Access Layer  responsible for placing TCP/IP packets on the network medium and receiving TCP/IP packets off the network medium.   designed to be independent of the network access method, frame format, and medium. In this way, TCP/IP can be used to connect differing network types. These include LAN technologies such as Ethernet and Token Ring and WAN technologies such as X.25 and Frame Relay. 

3. Internet Layer (IP) The Internet layer is responsible for addressing, packaging, and routing functions. The core protocols of the Internet layer are IP, ARP, ICMP, and IGMP. The Internet Control Message Protocol (ICMP) is responsible for providing diagnostic functions and reporting errors due to the unsuccessful delivery of IP packets.

4. Transport Layer (TCP) The Transport layer (also known as the Host-to-Host Transport layer) is responsible for providing the Application layer with session and datagram communication services. The core protocols of the Transport layer are Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP). Reliable delivery of data. Ordering of delivery.

5. Application Layer The Application layer provides applications the ability to access the services of the other layers and defines the protocols that applications use to exchange data. There are many Application layer protocols and new protocols are always being developed. Support for user applications e.g. http, SMPT

OSI v TCP/IP

Some of TCP/IP Protocol suite Telnet FTP SNMP Created By Dr.Najla AlNabhan edited by Maysoon AlDuwais

TCP/IP Protocol suite (Telnet) Allow users to make remote connections based on the Telnet protocol. Using a local command prompt window, you can run command line programs, shell commands, and scripts in a remote command console session just as you were locally logged on to the host. Created By Dr.Najla AlNabhan edited by Maysoon AlDuwais

TCP/IP Protocol suite (Telnet) Thus, having Telnet client and server software solves two networking problems. It allows for interoperability between disparate operating systems, and it facilitates administration of remote systems, saving administrative time and network resources. Created By Dr.Najla AlNabhan edited by Maysoon AlDuwais

TCP/IP Protocol suite (FTP) FTP is an acronym for File Transfer Protocol. FTP is used to transfer files between computers on a network. You can use FTP to exchange files between computer accounts, transfer files between an account and a desktop computer, or access online software archives. Created By Dr.Najla AlNabhan edited by Maysoon AlDuwais

TCP/IP Protocol suite (FTP) For example, in the case of creating a Web site, this means that if you create the pages for your site on your computer, either using a text editor or some other Web page editor, then you will need to move it to the server where your site will be hosted. FTP is the main way to do this. Created By Dr.Najla AlNabhan edited by Maysoon AlDuwais

TCP/IP Protocol suite (SNMP) SNMP is a standard TCP/IP protocol for network management.   Network administrators use SNMP to monitor and map network availability, performance, and error rates. It is used for configuring and collecting information from network devices, such as servers, printers, hubs, switches, and routers on an Internet Protocol (IP) network. Created By Dr.Najla AlNabhan edited by Maysoon AlDuwais

Addressing Level Level in architecture at which entity is named Unique address for each end system (computer) and router - Network addressing level: IP or internet address (TCP/IP) Network service access point or NSAP (OSI)

Hostnames and DNS Servers - The “real” name of a computer on the internet is its four-byte IP address. People, however, don’t like to remember numbers, so we use hostnames instead. For example, the hostname www.cis.upenn.edu is 158.130.12.9. A DNS (Domain Name Server) is a computer that translates hostnames into IP addresses. Naming system for computers, services, or other resources connected to the Internet or a private network.

Hostnames and DNS Servers Example: - When you type in a web address, e.g., www.jimsbikes.com, your Internet Service Provider views the DNS associated with the domain name, translates it into a machine friendly IP address (for example 216.168.224.70 is the IP for jimsbikes.com) and directs your Internet connection to the correct website. 

DHCP - If you have a web site, it must be hosted on a computer that is “permanently” on the Web. This computer must have a permanent IP address. There aren’t enough IP addresses for the number of computers there are these days. If you have no permanent web site, you can be given a temporary (dynamically allocated) IP address each time you connect to the Web. DHCP (Dynamic Host Configuration Protocol) is a way of assigning temporary IP addresses as needed

URLs - A URL is the fundamental network identification for any resource connected to the web. A URL, Uniform Resource Locater, defines a location on the Web. A URL has up to five parts: https://ct1503.wordpress.com:80/about/#

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