CE 536 - Networking and Microcomputer Systems

Day 8: Network Protocols, the Internet, and Internet Services

The Internet

TCP/IP

Domain Name System

BOOTP

Internet Documentation

Internet Organizations

Internet Services

Electronic Mail

Usenet News

Anonymous FTP

World-Wide Web

Information Browsers

The Internet - A worldwide collection of interconnected networks

Linked by a common set of technical protocols

The TCP/IP Protocol Suite -

Transmission Control Protocol/Internet Protocol

 Mail Gateways - provide electronic mail links to non-TCP/IP based networks

BITNET - mail only

CompuServe - mail with full Internet access

Prodigy - mail with full Internet access

America OnLine - mail with full Internet access

 Over 10,000 Interconnected Networks

Over 1.5 Million Host Computers

Finding the Address of an Internet Host

InterNIC WHOIS Database (telnet internic.net) (www.internic.net)

American Registry for Internet Numbers (www.arin.net)

RIPE NCC Database (www.ripe.net)

Reseaux IP Europeens Network Coordination Centre

Amsterdam, The Netherlands

 Call up the Organization and Ask THEM!

TCP/IP - Transmission Control Protocol/Internet Protocol

A family of over 100 data-communications protocols

TCP - Transmission Control Protocol (STD 7)

Host to Host (Transport) Layer - assures reliable communication between hosts

IP - Internet Protocol (STD 5)

Internet (Network) Layer - handles the routing of data

 SMTP - Simple Mail Transfer Protocol (STD 10)

Process (Application) Layer

Electronic Mail

 SNMP - Simple Network Management Protocol (STD 15)

Process (Application) Layer

Network Management

 FTP - File Transfer Protocol (STD 9)

Process (Application) Layer

File Transfer

ftp hostname

 ascii - for ASCII (text) transfers

binary - for binary file transfers

get filename newfilename

 retrieve a single file - optional rename

 mget filename*

 retrieve multiple files - * wildcard

 put filename newfilename

 send a single file - optional rename

 mput filename*

 send multiple files - * wildcard

 cd, ls -l, dir - remote computer commands

lcd, !ls -l, !dir - local computer commands

 TELNET Protocol (STD 8)

Process (Application) Layer

Terminal Emulation

telnet hostname

 open hostname

 close

quit

 VT-100 Terminal Emulation

TN3270 - IBM 3270 Terminal Emulation

 RLOGIN

Passes terminal information (e.g. username)

Handles flow control

Domain Name System (DNS) - a hierarchical, distributed method of organizing the name space of the Internet

Fully Qualified Domain Name - a domain name that includes all higher-level domains

                 ds1.allencol.edu   ns1.cc.lehigh.edu
Host name:            ds1                ns1
Subnet:                                  cc
Subdomain:            allencol           lehigh
Top-level Domain:     edu                edu
Top-Level Domains

com, org, net, edu, gov, mil

 Second-Level Domain (e.g., lehigh, allencol)

Domain names correspond to a 32-bit IP address

Five classes of Internet addresses

Class     First Octet    # Networks      Maximum Nodes
A          000-127           127        16.5 Million (255x255x255)
B          128-191         16383        65025 (255x255)
C          192-223       4 Million+      255
D          224-239       Multicasting (Router updates)
E          240-255       Experimental
Internet addresses are of the form

147.106.xxx.xxx (Allentown College)

147.106.1.5 (Allentown College's WWW Server)

128.180.xxx.xxx (Lehigh University)

 NSLOOKUP - an interactive domain name server program

BOOTP - Boot Protocol

BOOTP Table - utility to match Ethernet addresses to IP addresses

Useful in networked environments in which only a single copy of a TCP/IP application is loaded on the file server

Internet Documentation

RFC - Request for Comments

Descriptions of network protocols or services

Never revised or re-issued with the same number

Always get the most recent RFC on a particular protocol ("Internet Official Protocol Standards" - currently RFC 2200 - STD 1)

 FYI - For Your Information

Subset of the RFC series - assigned both an FYI number and an RFC number - if updated, released with a new RFC number but the FYI number stays the same - FYI 4 will always be FYI 4; currently is RFC 1594, was RFC 1325)

Information oriented

 STD - Standard

RFCs that document Internet standards

A Standard may be documented with multiple RFCs (e.g., STD 13 Domain Name System - currently documented by RFC 1034 and RFC 1035)

STD number stays the same even if documented by new RFCs

 Primary Repositories of Internet Documentation

ftp ds.internic.net (Internet Network Information Center)

ftp nis.nsf.net (National Science Foundation)

ftp ftp.isi.edu (Information Sciences Institute)

ftp ftp.merit.net

ftp nisc.jvnc.net

ftp ftp.concert.net

ftp wuarchive.wustl.edu

Internet Organizations

IAB - Internet Architecture Board - concerned with technical and policy issues involving the Internet architecture

IETF - Internet Engineering Task Force - coordinates the operation, management, and evolution of the Internet

IRTF - Internet Research Task Force - promotes research in networking and the development of new technology

IANA - Internet Assigned Numbers Authority - responsible for assigning numbers to protocol parameters

version numbers

port numbers

currently at USC/ISI (U. of Southern California/Information Sciences Institute)

 InterNIC - Internet Network Information Center - provides network information services to the networking community - originally formed by General Atomics, AT&T, and Network Solutions, Inc.

Network Solutions, Inc. (NSI) - provides Registration Services

Internet Registry

IP address allocation

Domain name registration

Delegates some number assignment authority to regional registries

RIPE - Reseaux IP Europeens

 ARIN - American Registry for Internet Numbers - non-profit

established to manage the allocation of IP numbers for areas

previously managed by InterNIC (www.arin.net)

Internet Services

Electronic Mail

One of the most heavily used Internet resources

The WHOIS server (telnet internic.net) can often tell you the

domain name of an institution

Some institutions have centralized mail systems (e.g., lehigh.edu)

so all you need to know is the user id of the individual to whom

you wish to send mail

White Pages

Yellow Pages

Finger

postmaster@institution.domain

For privacy, some institutions will not divulge id's

 BITNET LISTSERV's - Internet mailing lists

Postings are sent to the LISTSERV system

LISTSERV system sends the posting to list subscribers

Moderated and unmoderated lists

Can overburden computing systems

 Electronic Communications Privacy Act of 1986

(18 USC 2701-2711) - governs the use of electronic mail on public systems

Every organization should have a written policy on the use of electronic mail by individuals within the organization especially if the organization does not conform to the ECPA

Law enforcement authorities may request the electronic mail of an individual through a court order

Back-up electronic mail as part of the normal system back-up schedule

 Electronic mail can be forged

Law enforcement authorities may request system records through a court order to track down the perpetrator

POP (Post Office Protocol) Mailers

mail downloaded from a mail server

mail is usually removed from the server

 used extensively with PC's and Web browsers

especially easy to use for forged mail

 IMAP (Internet Message Access Protocol)

mail downloaded from a mail server as needed

mail remains on the server

 used extensively with PC's and Web browsers

especially easy to use for forged mail

 Anonymous Mailers - systems to which an individual may send a message for forwarding - the system strips off the header information from the message so the person receiving the message will not know who sent it

Mail from that site can be blocked, once you know about it...

Often outside of the country (e.g., Finland has a lot of them)

Usenet News - a distributed computer information service which handles thousands of discussion groups

Moderated and Unmoderated Groups

Postings go to thousands of locations around the world

Mirrors a number of LISTSERV's (i.e., contains everything posted to a select group of LISTSERV's) - e.g., bit.listserv.edtech

NNTP - Network News Transfer Protocol

No centralized authority - self policing

Anonymous FTP - allows users to obtain public files from a host computer - often incorporated into Web browser file downloads

User name of: anonymous

Password of: guest (or your normal user id)

Often used for product updates and patches

For distribution of public-domain and shareware packages

You may want to pay for your shareware!

 World-Wide Web - a distributed, hypermedia-based Internet information system

Fastest growing information base on the Internet (by far!)

Text, graphics, images, audio, video, etc.

Client/Server

Client - software which interprets data from the server

Server - delivers (possibly non-standard) data in a standard format

 Information Browsers - allow access to Internet information in all major forms - WWW, gopher, telnet, ftp, etc.

Mosaic - the first browser - developed by NCSA (National Center for Supercomputing Applications)

Netscape - the most popular browser (this week...)

Internet Explorer - Microsoft's browser

URL - Universal Resource Locator

Specifies transfer protocol to be used

Specifies host computer containing the information

Specifies location of the information

Specifies file containing the information

http://hostname/location

http://www.allencol.edu

http://www.lehigh.edu/~brb0/brb0.html

hypertext transfer protocol

 index.html - default file name if none specified (depends on the client software being used)

html - hypertext markup language

being built into many word processors

MS-Word for Windows

WordPerfect for Windows

 file://location/name

file://c:/test/test.htm

name and location of an html document on the system on which the browser is running

 gopher://hostname

gopher://gopher.allencol.edu

gopher protocol

 telnet://hostname

telnet://ds1.allencol.edu

telnet protocol

 ftp://hostname

ftp://ftp.lehigh.edu

file transfer protocol

 Options allow browsers to be customized

Name of Mail Server (SMTP)

Name of News Server (NNTP)

Helper Applications

Video viewers

.avi - Video for Windows

.mov, .qt - Quicktime

.mpeg, .mpg - Motion Picture Experts Group

 Audio viewers

.wav - Windows sound file

.au - Sun sound file

 Image viewers

.gif - Graphic Interchange Format

.jpeg - Joint Photographer Experts Group

.tif, .tiff - Tagged Image Format

 Bookmarks - allow URL's to be saved for future use

Assignment for Class 11 ...

Read and be prepared to discuss:

Chapter 12 - skip Banyan's VINES (pages 342-349)

- skip DEC's Pathworks (pages 354-355)

 Chapter 13

Chapter 15