Download
1 / 40
500 likes | 821 Vues
Internet Standards and Services. Chapter 12. Objectives. In this chapter, you will learn to: Summarize the history of today’s Internet Identify the organizations that cooperate to set Internet standards Explain conventions for Internet domain and host naming
E N D
Internet Standards and Services Chapter 12
Objectives In this chapter, you will learn to: • Summarize the history of today’s Internet • Identify the organizations that cooperate to set Internet standards • Explain conventions for Internet domain and host naming • Describe several popular Internet-based services and identify the protocols on which they rely • Run and interpret the output of simple TCP/IP-based utilities
The Evolution of the Internet • Advanced Research Projects Agency (ARPA) - an organization formed by the United States government in 1958 to investigate and develop new military defense technology. • ARPANET - a network that relied on telephone lines to transmit messages that had been fragmented into small packages of data between computers. • Domain Name System (DNS) - a formal, centralized method for automatically associating IP addresses with host names. • NSFNET - supercomputing centers at five universities across the nation plus a backbone to connect them with each other and, with other organizations. • World Wide Web (WWW) - a collection of multiple Internet servers and a method for organizing data scattered over these servers.
Technical Specifications • Internet draft - a thorough explanation of a proposed standard. • Internet Engineering Steering Group (IESG) - a committee made of IETF technical area directors that oversees IETF decisions. • Request for Comments (RFC) - a numbered document that articulates some aspect of Internet technology. • Proposed standard - reclassified Internet draft. • Draft standard - a proposed standard that has been successfully by at least two independent researchers.
Address Assignments and Naming • Internet Assigned Numbers Authority (IANA): • kept records of available and reserved IP addresses. • was also responsible for allocating domain names and maintaining the Domain Name System (DNS). • Regional Internet Registries (RIRS) - a not-for-profit agency that manages the distribution of IP addresses to private and public entities. • Internet Corporation for Assigned Names and Numbers (ICANN) - a private nonprofit corporation that is contracted by the government to oversee IP addresses and domain name management, plus accomplish specific Internet management improvements.
Host and Domain Naming • TCP/IP is a protocol suite that contains several subprotocols. • Some subprotocols, such as TCP, are connection-oriented. • Connectionless subprotocols do not guarantee data delivery, but can transmit data faster than connection-oriented subprotocols. • Every addressable computer connected to a TCP/IP network is known as a host. • Every host can take a host name, a name that describes the device.
Host and Domain Naming • Each host belongs to a domain, which also has a name. • Every host on a TCP/IP network requires a unique IP address to communicate with other hosts. • Each IP address is a unique 32-bit number, divided into four octets, or 8-bit bytes.
Domain Name System (DNS) • A hierarchical way of identifying domain names and their addresses. • Relies on a database, which is distributed over 13 key computers, known as root servers, across the Internet. • The last label in a domain name represents a top-level domain (TLD), or the highest level in a DNS hierarchy. • For example, in the www.fcc.gov domain, the TLD is “gov.”
Name Servers and Space • Name space - the database of Internet IP addresses and their associated names. • Resource Record - a single record that describes one piece of information in the DNS table. • Resolvers - any host on the Internet that need to look up domain name information and associate it with an IP address. • Name servers (DNS servers) - contain databases of names and their associated IP addresses.
The Use of Ports • The logical address on a host where an application makes itself available to incoming data. • The use of port numbers simplifies TCP/IP communications and ensures that data are transmitted to the correct application. • Port numbers can have any numeric value from 0 to 65536. • Port numbers in the range of 0 through 1023 are referred to as well known port numbers.
World Wide Web (WWW) • On the client side, access to the Web requires TCP/IP, a unique IP address, a connection to the Internet, and a browser. • On the server side, a Web site requires TCP/IP, a connection to DNS servers, routers, Web server software, and a connection to the Internet.
Hypertext Transfer Protocol (HTTP) and Hypertext Markup Language (HTML) • HTTP - operates at the Application layer of the TCP/IP model. • HTML - the Web document formatting language. • World Wide Web Consortium (W3C) - a standards organization for Web browsers and languages. • Tags - formatting indicators.
Hypertext Transfer Protocol (HTTP) and Hypertext Markup Language (HTML)
Simple Mail Transfer Protocol (SMTP) • Operates in the Application layer of the TCP/IP model and relies on TCP at the Transport layer. • Operates from TCP port 25. • SMTP is a simple subprotocol, incapable of doing anything more than transporting mail or holding it in a queue.
Post Office Protocol • Provides centralized storage for e-mail messages. • Users need an SMTP-compliant mail program to connect to their POP server and download mail from storage. • POP does not allow users to store mail on the server after they download it.
Internet Mail Access Protocol (IMAP) • Features: • Users can retrieve all or only a portion of any mail message. • Users can review their messages and delete them while the messages remain on the server. • Users can create sophisticated methods of organizing messages on the server. • Users can share a mailbox in a central location. • IMAP4 can provide better security than POP because it supports authentication.
File Transfer Protocol (FTP) • FTP commands: • ascii: Sets the file transfer mode to “ASCII.” • binary: Sets the file transfer mode to “binary.” • cd: Changes your working directory on the host machine. • delete: Deletes a file on the host machine • get: Transfers a file from the host machine to the client. • help: Provides a list of commands when issued from the FTP prompt. • ls: Lists the contents of the directory on the host where you are currently located. • mkdir: - Creates a new directory on the FTP host. • open: Creates a connection with an FTP host.
Newsgroups • Provide a means of conveying messages • Distributed to a wide group of users at once rather than from user to another • Newsgroup messages are transported by the Network News Transfer Protocol (NNTP). • NNTP operates via TCP port 119.
Internet Telephony • Voice over IP (VoIP) - Breaks voice signals into packets and transmits them over data networks using TCP/IP. • When VoIP is carried over the Internet, it is known as Internet telephony.
Intranets and Extranets • Intranet - a network or part of a network that uses Internet like services and protocols to exchange information within an enterprise. • Also used for e-mail, file sharing, document management, and collaboration. • Extranet - a network that uses Internet-like services and protocol to exchange information over a broad geographical area. • Encompasses dedicated connections to multiple offices within a company.
Ipconfig • The TCP/IP administration utility for use with Windows NT, 2000, and XP operating system. • Provides information about a NIC’s IP address, subnet mask, and default gateway. • Can be used with switches to manage a computer’s TCP/IP settings, including your MAC address and the address of your WINS server.
Ipconfig • Popular switches: • ?: display a list of switches available for use with the ipconfig command. • /all: displays complete TCP/IP configuration information for each network interface on that device. • /release - releases DHCP-assigned addresses for all of the device’s network interfaces. • /renew - renews DHCP-assigned addresses for all of the device’s network interfaces.
Ifconfig • The TCP/IP configuration and management utility used on UNIX systems. • Popular switches: • -a: Applies the command to all interfaces on a device. • down: Marks the interface as unavailable to the network. • -up: Reinitializes the interface after it has been taken “down,” so that it is once again available to the network.
Ping • Can be used to verify the installation of TCP/IP. • Relies on the Internet control Message Protocol (ICMP), which is a TCP/IP protocol that notifies the sender that something has gone wrong in the transmission process and the packets were not delivered. • Helpful in diagnosing local connectivity problems.
Ping • Common Switches: • -?: Displays the help text for the PING command, including its syntax and a full list of switches. • -a: When used with an IP address, resolves the address to a host name. • -n: Allows you to specify a number of echo requests to send. • r: When used with a number from 1 to 9, displays the route taken during ping hops. • -w: Limits the time to wait for each echo response to a specific number of milliseconds.
Traceroute • Uses ICMP to trace the path from one host to another, identifying all intermediate hops between the two hosts. • Useful for determining router or network connectivity problems. • Common switches: • -d: Instructs the tracert command not to resolve IP addresses to host names. • -h: Specifies the maximum number of hops the packets should take when attempting to reach a host. • -w: Identifies a timeout period for responses.
Netstat • Displays TCP/IP statistics and details about TCP/IP components and connections on a host. • Information that can be obtained include: • the port on which a particular TCP/IP service is running. • whether or not a remote node is logged on to a host. • which network connections are already established for a client. • how many packets have been handled by a network interface since it was activated. • How many data errors have occurred on a particular network interface.
Netstat • Common switches: • -a: Provides a listing of all available TCP and UDP connections, even if they are simply listening and not currently exchanging data. • -e: Displays details about all the packets that have been sent over a network interface. • -n: Lists currently connected hosts according to their port and IP address. • -p: Allows you to specify what type of protocol statistics to list. • -R: Provides a list of routing table information. • -S: Provides statistics about each packet transmitted by a host, separated according to protocol type.
Summary • In 1969, the wide area network that would later become part of the Internet was known as ARPANET. • TCP/IP became the protocol for the Internet after it was codified in 1972. It was designed to facilitate open communication between all computers. • DNS is a hierarchical way of identifying domain names and their addresses. It relies on a database that is distributed over 13 root servers across the Internet.
