Basic Network ServicesBasic Network Services

IMT 546 – Lab 4IMT 546 – Lab 4December 4, 2004December 4, 2004Agueda SánchezAgueda SánchezShannon Shannon Layden Layden Peyman TajbakhshPeyman Tajbakhsh

Basic Network ServicesBasic Network Services• What network services areWhat network services are• What network protocols areWhat network protocols are• Three widely used protocolsThree widely used protocols

TCP/IPTCP/IP HTTPHTTP

• DemoDemo SMTPSMTP

• ExampleExample

• One new protocolOne new protocol IPv6IPv6

What Network Services areWhat Network Services are

Network services are the capabilities Network services are the capabilities that enable computers to that enable computers to communicate with each othercommunicate with each other

Protocols define how they do it (the Protocols define how they do it (the rules)rules)

In the TCP/IP model, “services” and In the TCP/IP model, “services” and “protocols” are often used “protocols” are often used interchangeablyinterchangeably

Network ProtocolsNetwork Protocols Protocols allow information to travel over the Protocols allow information to travel over the

networknetwork There are different types of protocolsThere are different types of protocols Each protocol has a set of “rules” and agreementsEach protocol has a set of “rules” and agreements Information can be exchanged between computers Information can be exchanged between computers

because they have "agreed" to use the same because they have "agreed" to use the same protocolprotocol

Connecting with X protocol; ready to receive instruction or message?

Yes, I'm ready to receive message (ack)

Send message or instruction

Packet DriverProtocols

Product SpecificDriver

Link AccessProtocol Balance

(LAPB)

Internet Protocol (IP)

Transmission Control Protocol (TCP) User Datagram Protocol (UDP)

Internet Message Access Protocol (IMAP)

File Transfer Protocol

(FTP)

TELNETVirtual

Terminal Protocol

Simple Mail

Transfer Protocol (SMTP)

Remote File Service (RAs) Network File System (NFS)Server Message Block

(SMB)

Network File System (NFS) Redirector

TCP-aware Applications(browser, IRC, News Reader, and more)

Derfler F.J. Jr. , Freed, L., How Networks Work, (2003)

TC

P/IP

ST

AC

KT

CP

/IP S

TA

CK

Application

Transport

Internet

Host to network

An Introduction to TCPAn Introduction to TCP TCP stands for TCP stands for Transmission Control Transmission Control

Protocol Protocol It controls the transmission of packets of It controls the transmission of packets of

data over the Internetdata over the Internet It supports the network at the transport It supports the network at the transport

layerlayer Computers must run TCP to communicate Computers must run TCP to communicate

with world wide web serverswith world wide web servers TCP relies on the IP service to deliver data TCP relies on the IP service to deliver data

to the hostto the host

An Introduction to IPAn Introduction to IP IP stands of Internet ProtocolIP stands of Internet Protocol A set of rules to send and receive A set of rules to send and receive

messages at the Internet address levelmessages at the Internet address level Computers must run IP to communicate Computers must run IP to communicate

across the internetacross the internet IP forwards each packet based on a four IP forwards each packet based on a four

byte destination address (the IP number) byte destination address (the IP number) (e.g, 192.156.1.1)(e.g, 192.156.1.1)

Demo IPCONFIG and PingDemo IPCONFIG and Ping

HTTPHTTP

transfer of data

Request

Hyper-text transfer protocol (HTTP) is the protocol for exchanging text, graphic images, sound, video, and other multimedia files on the Internet

HTTP …cont.HTTP …cont.

HTTP started in 1990 by Berners-LeeHTTP started in 1990 by Berners-Lee

1993 employed by Marc Andreeson of 1993 employed by Marc Andreeson of Netscape Netscape

Initial vision to create “a common Initial vision to create “a common information space in which we information space in which we communicate by sharing information“communicate by sharing information“

Estimated 80% of internet traffic is Estimated 80% of internet traffic is over http over http

How HTTP worksHow HTTP works

Client (browser usually) sends a Client (browser usually) sends a request to a serverrequest to a server

Request comes with a URL and Request comes with a URL and usually an operationusually an operation

Server performs operation on the Server performs operation on the URLURL

Server sends responseServer sends response

HTTP DemoHTTP Demo

GET /dumprequest.html HTTP/1.1 GET /dumprequest.html HTTP/1.1 Host: djce.org.ukHost: djce.org.uk

User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322) Accept: image/gif, image/x-NT 5.1; .NET CLR 1.1.4322) Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */* application/vnd.ms-powerpoint, application/msword, */* Accept-Encoding: gzip, deflate Accept-Language: en-us Accept-Encoding: gzip, deflate Accept-Language: en-us Referer: http://www.google.com/search?Referer: http://www.google.com/search?sourceid=navclient&ie=UTF-8&q=http+%22request+methodsourceid=navclient&ie=UTF-8&q=http+%22request+method%3A+Get%22++examples+get+http%2F1%2E1 Connection: Keep-%3A+Get%22++examples+get+http%2F1%2E1 Connection: Keep-

AliveAlive

SMTPSMTP

Mailbox StoreServer

Mailbox StoreMessage Delivery

Message Delivery

Server

SMTP: Simple Mail Transfer Protocol – A protocol used to send email on the Internet. SMTP is a set of rules regarding the interaction between a program sending email and a program receiving email

SMTP …cont.SMTP …cont. Email is delivered by having the source machine establish a Email is delivered by having the source machine establish a

TCP connection to port 25 of the destination machine. For TCP connection to port 25 of the destination machine. For successful delivery, both “sender” and “receiver” should successful delivery, both “sender” and “receiver” should "speaks" SMTP. "speaks" SMTP.

After establishing the TCP connection to port 25, the sending After establishing the TCP connection to port 25, the sending machine, operating as the client, waits for the receiving machine, operating as the client, waits for the receiving machine, operating as the server, to talk first.machine, operating as the server, to talk first.

SMTP …cont.SMTP …cont.

SMTP is used for sending e-mail. IMAP SMTP is used for sending e-mail. IMAP (Internet Message Access Protocol) and (Internet Message Access Protocol) and POP3 (Post Office Protocol 3) are used to POP3 (Post Office Protocol 3) are used to access e-mail messages. access e-mail messages.

POP3 or IMAP let the user save messages POP3 or IMAP let the user save messages in a server mailbox and download them in a server mailbox and download them periodically from the server.periodically from the server.

SMTP ExampleSMTP Example Date: Sat 27 Jun 87 13:26:31 EDT Date: Sat 27 Jun 87 13:26:31 EDT From: hedrick@topaz.rutgers.edu From: hedrick@topaz.rutgers.edu To: levy@red.rutgers.edu To: levy@red.rutgers.edu Subject: meeting Let's get together Monday at 1pm.Subject: meeting Let's get together Monday at 1pm.

RED 220 RED.RUTGERS.EDU SMTP Service at 29 Jun 87 05:17:18 EDTRED 220 RED.RUTGERS.EDU SMTP Service at 29 Jun 87 05:17:18 EDT TOPAZ HELO topaz.rutgers.edu TOPAZ HELO topaz.rutgers.edu RED 250 RED.RUTGERS.EDU - Hello RED 250 RED.RUTGERS.EDU - Hello TOPAZ.RUTGERS.EDUTOPAZ.RUTGERS.EDU TOPAZ MAIL From: TOPAZ MAIL From: RED 250 MAIL accepted RED 250 MAIL accepted TOPAZ RCPT To:TOPAZ RCPT To: RED 250 Recipient acceptedRED 250 Recipient accepted TOPAZ DATA TOPAZ DATA RED 354 Start mail input; end with . RED 354 Start mail input; end with . TOPAZ Date: Sat 27 Jun 87 13:26:31 EDT TOPAZ Date: Sat 27 Jun 87 13:26:31 EDT TOPAZ From: hedrick@topaz.rutgers.edu TOPAZ From: hedrick@topaz.rutgers.edu TOPAZ To: levy@red.rutgers.edu TOPAZ To: levy@red.rutgers.edu TOPAZ Subject: meeting TOPAZ Subject: meeting TOPAZ TOPAZ TOPAZ Let's get together Monday at 1pm. TOPAZ Let's get together Monday at 1pm. TOPAZ . TOPAZ . RED 250 OK RED 250 OK TOPAZ QUIT TOPAZ QUIT RED 221 RED.RUTGERS.EDU Service closing transmission channel RED 221 RED.RUTGERS.EDU Service closing transmission channel

What is IPv6?What is IPv6?To understand IPv6 lets review IPv4To understand IPv6 lets review IPv4

Current version of the Internet Protocol Current version of the Internet Protocol used by TCP/IPused by TCP/IP

IPv4 has not substantially changed since IPv4 has not substantially changed since RFC 791 was published in 1981RFC 791 was published in 1981

Robust, easily implemented and Robust, easily implemented and interoperable, and has stood the test of interoperable, and has stood the test of scaling to the size of today’s Internetscaling to the size of today’s Internet

Impending exhaustion of IPv4 address Impending exhaustion of IPv4 address space due to exponential growth of space due to exponential growth of InternetInternet

IPv6IPv6

IPv4IPv4 IPv6IPv6

Addresses are 4 bytes in Addresses are 4 bytes in lengthlength

Addresses are 16 bytes in Addresses are 16 bytes in lengthlength

Security OptionalSecurity Optional Security RequiredSecurity Required

Header includes optionsHeader includes options Extension headers Extension headers (extensibility)(extensibility)

Address Resolution Address Resolution Protocol (ARP)Protocol (ARP)

Neighbor Solicitation Neighbor Solicitation MessagesMessages

Configured manual or via Configured manual or via DHCPDHCP

Does not require manual or Does not require manual or DHCP configurationDHCP configuration

Must support a 576-byte Must support a 576-byte packet size (possibly packet size (possibly fragmented).fragmented).

Must support a 1280-byte Must support a 1280-byte packet size (without packet size (without fragmentation). fragmentation).

There are 14 key differences between IPv4 and There are 14 key differences between IPv4 and IPv6, some of the key differences are:IPv6, some of the key differences are:

IPv4 Header ReviewIPv4 Header ReviewVersion

Internet Header LengthType of Service

Total LengthIdentification

FlagsFragment Offset

Time to LiveProtocol

Header ChecksumSource Address

Destination AddressOptions . . .

IPv6 HeaderIPv6 HeaderVersion

Traffic Class

Flow Label

Payload Length

Next Header

Hop Limit

Source Address

Destination Address

TCP/IP Protocol Architecture w/IPv6TCP/IP Protocol Architecture w/IPv6

IPv6

TCP

FTP

UDP

MLD

Telnet HTTP RIPngDNS SNMP

Internet Layer

Transport Layer

Application Layer

Network Interface Layer

Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

OSI Model Layers

TCP/IP Protocol Architecture

Layers

TCP/IP Protocol Suite

Ethernet Token Ring Frame Relay ATM

ND

ICMPv6

ResourcesResources TCP

• http://www.atlantawebhost.com/glossary-sz.php IP

• http://www.atlantawebhost.com/glossary-hl.php

HTTP• Derfler F.J. Jr. , Freed, L., How Networks Work, (2003)• http://www.w3.org/Protocols/HTTP/HTTP2.html• http://www.cs.virginia.edu/~zaher/classes/CS457/lectures/web.pdf• http://www.jmarshall.com/easy/http/

SMTP• https://www.namesecure.com/en_US/index.jhtml?cat=glossary&subCat=

rst#smtp• http://www.lsoft.com/resources/glossary.asp#S• http://searchwebservices.techtarget.com/sDefinition/

0,,sid26_gci214219,00.html• http://www2.rad.com/networks/1998/smtp/smtp.htm• http://networking.ittoolbox.com/pub/LC030701a.pdf

Microsoft’s IPv6 web site• http://www.microsoft.com/windowsserver2003/technologies/ipv6/default.

mspx