Class #12

1. Class #12 Chapter 12 - Internet Standards and Services

2. Internet Standards and Services Objectives In this section, 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

3. The Evolution of the Internet • Defense Advanced Research Projects Agency (ARPA or DARPA) - an organization formed by the United States government in 1958 to investigate and develop new military defense technology, including reliable wartime communications. • ARPANET – the 1969 ARPA network that originally relied on telephone lines and UUCP to transmit messages that had been fragmented into small packages of data between computers. • By 1972, email was first transmitted • By 1974, TCP/IP was implemented to facilitate open communications across the various computers connected to ARPANET. • By 1982, the size of ARPANET required that centralized, automatic association of IP addresses with URLS become reality. • By 1986, the National Science Foundation funded the creation of supercomputing centers at 5 universities. These centers, and the backbones were known as NSFNET. • As private organizations, NSFNET, and ARPANET began to merge into the Internet, the number of total hosts swelled to over 300,000 by 1990. • The 1991-1994 development of the World Wide Web (WWW), a collection of multiple servers with a method for organizing and formatting the data on them, made the Internet much easier to use and paved the way for commercial and casual users to use the network.

4. Technical Specifications The following is the sequence of events that must occur before a proposal, new protocol, or unique method is accepted as an Internet standard: • Internet draft - a thorough explanation of a proposed standard is sent to an existing standard’s working group that is associated with the proposed change. • Internet Engineering Steering Group (IESG) - a committee made of Internet Engineering Task Force technical area directors that oversees IETF decisions regarding working group drafts. • Request for Comments (RFC) – If the working draft is approved for standardization, a numbered document is published for general comment. • Proposed standard – The RFC is the reclassified Internet draft. Roughly 1/10 proposals make it this far. • Draft standard - a proposed standard that has been successfully duplicated or proven by at least two independent researchers. The proposed standard must also be in line with existing draft standards for related technologies.

5. Technical Specifications, cont.

6. Address Assignments and Naming • Each node on a TCP/IP network needs a unique IP address, from the finite quantity of available addresses. Historically (<1997), NAPs and ISPs get their address blocks from the Internet Assigned Numbers Authority (IANA), which: • kept records of available and reserved IP addresses. • was also responsible for allocating domain names and maintaining the Domain Name System (DNS). • IANA also coordinated with Regional Internet Registries (RIRS) – 3 not-for-profit agencies that manages the distribution of IP addresses to private and public entities in various geographic regions • ARIN – American Registry for Internet Numbers • APNIC – Asia Pacific Network Information Center • RIPE – Reseaux IP Europeens • A late 1990’s overhaul of the system, to increase competition and efficiency, resulted in the 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 managementimprovements. • Among other things, ICANN oversees the current registrar industry in the US.

7. Host and Domain Naming • A Basic review of TCP/IP: • 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. • 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.

8. Host Files • In the early days of ARPANET, URL-to-IP resolution was maintained in a hosts file – a text file maintained on a computer at University of Southern California. • However, the growth of ARPANET caused these problems: • The large number of hosts made the file unmanageable • Every other host had to access this single file/computer – causing severe network problems • This file/computer was a single point of failure for the entire network.

9. Domain Name System (DNS) • The basis of DNS is 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.” Each nation also has a 2-letter TLD

10. Domain Name System (DNS), cont. Many name servers, in addition to the 13 root servers that all the other refer to for information, operate across the globe to keep track of IP addresses and their associations with domain URLs. • Name space – all DNS servers comprise 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 (such as an IP address or a reference to another URL). Each defined URL has a resource record. To route traffic efficiently, DNS is divided into 3 components • Resolver – the client on a host on the Internet that looks up domain name information and associate it with an IP address. • Name servers (DNS servers) - contain databases of names and their associated IP addresses. • Zone --a collection of devices/URLs that a local name server is the authority for. A collection of resource records for a single zone is called a zone file.

11. Class Exercise #1 • Assume that you are host “lab12.collegeamerica.com”. Trace the DNS hierarchy steps needed to resolve the following: • www.collegeamerica.com • www.cisco.com • www.colostate.edu • www.hosting.ibm.net

12. The Use of Ports • A port number is a 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. This means that there can be up to 65537 different application layer services at any given IP address.

13. The Use of Ports, cont. • Port numbers in the range of 0 through 1023 are referred to as well known port numbers, and are defined by RFC 3232. • Other ports, outside the WKPN, are available for use by industry and developers

14. Class Exercise #2 • Identify the applications for these WKPNs: • Time • WhoIs • NNTP • SSH • Identify the applications for these port numbers: • 79 • 5631 • 8080 • http://www.iss.net/security_center/advice/Exploits/Ports/

15. The World Wide Web (WWW) Service The WWW is a collection of servers that follows specific protocols for formatting data on the Internet. • 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, Web server software, and a connection to the Internet. • To use a Uniform Resource Locator (URL), a DNS server with the appropriate zone file must be available, along with a registered domain name.

16. The World Wide Web (WWW) Service, cont. • Hypertext Transport Protocol (HTTP) – the application-layer protocol that allows web servers and browsers to communicate over WKNP 80. • Hypertext Markup Language (HTML) - the Web document formatting language created in 1991 by the World Wide Web Consortium (W3C) standards organization for Web browsers and languages. • The bases for HTML are tags -- which are formatting indicators, and anchors – which format information for redirection to other Web content.

17. The World Wide Web (WWW) Service, cont.

18. Browser Uniform Resource Locators (URLs)

19. Mail Services • Simple Mail Transfer Protocol (SMTP) is the service responsible for moving messages from one mail server to another. • It operates in the Application layer of the TCP/IP model (port 25) and relies on TCP at the Transport layer. • SMTP is a simple subprotocol, incapable of doing anything more than transporting mail or holding it in a queue. It requires higher-level APIs to feed it instructions. • To configure an email client, you have to identify the SMTP server over which mail is sent out.

20. Mail Services, cont. • Post Office Protocol (POP) 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 to the client.

21. Mail Services, cont. • Internet Mail Access Protocol (IMAP) is an improvement over POP, as it 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.

22. File Transfer Protocol (FTP) The FTP service manages file transfers between TCP/IP hosts over ports 20 and 21. • 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 • put: transfers a file from the client to the host. • 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. • hash: marks the progress of your download/upload

23. File Transfer Protocol (FTP)

24. Class Exercise #3 • Open a command line window and ftp to ftp.belnet.be • Login as “anonymous” • Password as “ftp” • Perform a list and change to the samba directory. • Download the latest samba tarball, using hashes to mark your progress. (note: this is a binary file) • After a few lines of hashes, close your DOS window to terminate the download.

25. Newsgroups Newsgroups are similar to email, as they provide a means of conveying messages. However it differs from email in that the messages are distributed to a wide group of users at once rather than from user to user. • Newsgroup messages are transported by the Network News Transfer Protocol (NNTP). • NNTP operates via TCP port 119. • Newsgroups have been subdivided by various domains (alt, biz, clari) and further divided by topic (sports, forsale, people). • The complete list of topics can be polled by the news client, which can then download the messages on user-selected topics.

26. Internet Telephony • Unlike traditional circuit-switch 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. • VoIP, when done over dedicated networks (such as intra-company), can be a significant savings over using the PSTN. • However, casual user Internet Telephony can be a bit erratic, and no standards exist for clients or servers.

27. 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.

28. Desktop Tools • IPCONFIG is the TCP/IP administration utility for use with Windows NT, 2000, and XP operating system. WINIPCFG is the equivalent tool for Win9x platforms. • 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.

29. Desktop Tools, cont. • 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.

30. Desktop Tools, cont. • The command line “ifconfig” is 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.

31. Desktop Tools, cont.

32. Desktop Tools, cont. • Ping (or “ping” in UNIX) 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.

33. Desktop Tools, cont. • Common Ping 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.

34. Desktop Tools, cont.

35. Desktop Tools, cont. • Tracert (or “traceroute” in UNIX) 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.

36. Desktop Tools, cont.

37. Class Exercise #4 • Determine the IP address, average latency over 25 tests, the colocation city and network for www.collegeamerica.com .

38. Desktop Tools, cont. • 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.

39. Desktop Tools, cont. • Common netstat 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.

40. 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 central database that is distributed over 13 root servers across the Internet. • Data bound for application-level services are logically separated by port numbers • Several connection-testing tools for TCP/IP include ping, traceroute, ipconifg, and netstat.

41. Assignments • Review Questions: (chap12) 1-25, • Hands-On Projects: 12-3(all)

42. End of Class Quiz • What organization provided funding for ARPANET? • If you want to reserve a domain name, what organization would you contact? • If you worked in Germany for an ISP, who would you apply to for IP addresses? • Where do you find the “hosts” file on a UNIX box? • What top level domain would be assigned to a US governmental agency?