Basic Network Services IMT 546 – Lab 4 December 4, 2004 Agueda Sánchez Shannon Layden Peyman Tajbakhsh

Basic Network Services What network services areWhat network services are What network protocols areWhat network protocols are Three widely used protocolsThree widely used protocols  TCP/IP  HTTP DemoDemo  SMTP ExampleExample One new protocolOne new protocol  IPv6

What Network Services are  Network services are the capabilities that enable computers to communicate with each other  Protocols define how they do it (the rules)  In the TCP/IP model, “services” and “protocols” are often used interchangeably

Network Protocols  Protocols allow information to travel over the network  There are different types of protocols  Each protocol has a set of “rules” and agreements  Information can be exchanged between computers because they have "agreed" to use the same protocol

TCP/IP STACK Application Transport Internet Host to network

An Introduction to TCP  TCP stands for Transmission Control Protocol  It controls the transmission of packets of data over the Internet  It supports the network at the transport layer  Computers must run TCP to communicate with world wide web servers  TCP relies on the IP service to deliver data to the host

An Introduction to IP  IP stands of Internet Protocol  A set of rules to send and receive messages at the Internet address level  Computers must run IP to communicate across the internet  IP forwards each packet based on a four byte destination address (the IP number) (e.g, )  Demo IPCONFIG and Ping

HTTP 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 started in 1990 by Berners-Lee  1993 employed by Marc Andreeson of Netscape  Initial vision to create “a common information space in which we communicate by sharing information“  Estimated 80% of internet traffic is over http

How HTTP works  Client (browser usually) sends a request to a server  Request comes with a URL and usually an operation  Server performs operation on the URL  Server sends response

HTTP Demo  GET /dumprequest.html HTTP/1.1 Host: djce.org.uk  User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;.NET CLR ) Accept: image/gif, image/x- xbitmap, image/jpeg, image/pjpeg, application/x- shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */* Accept-Encoding: gzip, deflate Accept-Language: en-us Referer: 8&q=http+%22request+method%3A+Get%22++examples+get+http% 2F1%2E1 Connection: Keep-Alive

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

SMTP …cont.  is delivered by having the source machine establish a TCP connection to port 25 of the destination machine. For successful delivery, both “sender” and “receiver” should "speaks" SMTP.  After establishing the TCP connection to port 25, the sending machine, operating as the client, waits for the receiving machine, operating as the server, to talk first.

SMTP …cont.  SMTP is used for sending . IMAP (Internet Message Access Protocol) and POP3 (Post Office Protocol 3) are used to access messages.  POP3 or IMAP let the user save messages in a server mailbox and download them periodically from the server.

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

What is IPv6? To understand IPv6 lets review IPv4  Current version of the Internet Protocol used by TCP/IP  IPv4 has not substantially changed since RFC 791 was published in 1981  Robust, easily implemented and interoperable, and has stood the test of scaling to the size of today’s Internet  Impending exhaustion of IPv4 address space due to exponential growth of Internet

IPv6 IPv4IPv6 Addresses are 4 bytes in length Addresses are 16 bytes in length Security Optional Security Required Header includes options Extension headers (extensibility) Address Resolution Protocol (ARP) Neighbor Solicitation Messages Configured manual or via DHCP Does not require manual or DHCP configuration Must support a 576-byte packet size (possibly fragmented). Must support a 1280-byte packet size (without fragmentation). There are 14 key differences between IPv4 and IPv6, some of the key differences are:

IPv4 Header Review Version Internet Header Length Type of Service Total Length Identification Flags Fragment Offset Time to Live Protocol Header Checksum Source Address Destination Address Options...

IPv6 Header Version Traffic Class Flow Label Payload Length Next Header Hop Limit Source Address Destination Address

TCP/IP Protocol Architecture w/IPv6 IPv6 TCP FTP UDP MLD TelnetHTTPRIPngDNSSNMP 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 EthernetToken RingFrame RelayATM ND ICMPv6

Resources   TCP   IP   HTTP Derfler F.J. Jr., Freed, L., How Networks Work, (2003)   SMTP =rst#smtp =rst#smtp   Microsoft’s IPv6 web site t.mspxhttp:// t.mspx