Internet Standards and Services

1
Internet Standards and Services

• Chapter 12

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Objectives

• In this chapter, you will learn to
• Summarize the history of todays 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

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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.

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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.

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Technical Specifications
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Technical Specifications
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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.

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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.

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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.

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Host Files
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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.

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Domain Name System (DNS)
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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.

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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.

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The Use of Ports
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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.

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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.

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Hypertext Transfer Protocol (HTTP) and Hypertext
Markup Language (HTML)
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Uniform Resource Locators (URLs)
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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.

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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.

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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.

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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.

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FTP
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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.

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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.

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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.

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Ipconfig

• The TCP/IP administration utility for use with
  Windows NT, 2000, and XP operating system.
• Provides information about a NICs IP address,
  subnet mask, and default gateway.
• Can be used with switches to manage a computers
  TCP/IP settings, including your MAC address and
  the address of your WINS server.

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Ipconfig
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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 devices network interfaces.
• /renew - renews DHCP-assigned addresses for all
  of the devices network interfaces.

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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.

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Ifconfig
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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.

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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.

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Ping
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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.

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Traceroute
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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.

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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.

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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.