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N. Ganesan, All rights reserved.
Chapter
Overview of TCP/IP
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Reference
Highly Recommended:
TCP/IP White Paper by Microsoft
http://www.microsoft.com/NTServer/nts/techdetails/compares/TCPIntrowp.asp?RLD=264http://www.microsoft.com/NTServer/nts/techdetails/compares/TCPIntrowp.asp?RLD=264 -
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Questions
How many layers are there in the TCP/IP model?How do they relate to the ISO-OSI model?
What are some of the TCP/IP related protocols? Explain the purpose and function of the above
protocols?
What are ports? Explain the implication of keeping
the ports open. How can the ports be protected fromhacker attacks?
Where would one use the UDP protocol in place ofthe TCP protocol?
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Chapter Modules
TCP/IP Overview and Layers
TCP/IP Related Protocols
TCP/IP Ports and Windows API
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N. Ganesan, All rights reserved.
Module
Overview of TCP/IP
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TCP/IP
A highly standardized protocol usedwidely on the Internet
Standards area available in the form ofRFC documents
Request For Comments (RFC)
Standards are overseen by the InternetEngineering Task Force (IETF)
http://www.ietf.org/rfc/http://www.ietf.org/http://www.ietf.org/http://www.ietf.org/http://www.ietf.org/http://www.ietf.org/rfc/ -
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Layers of TCP/IP ReferenceModel
There are four layers of the TCP/IP referencemodel (DARPA model as named by the US
Government Agency) The ISO-OSI reference model is composed of
seven layers
The next slide shows the mapping of the
ISO/OSI model to the TCP/IP model Note that the ISO/OSI model is more widely
used and accepted but the TCP/IP model iseasy to comprehend
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ISO-OSI Seven Layer ModelRecalled
Layer 7 ApplicationLayer 6 PresentationLayer 5
Session
Layer 4 TransportLayer 3 NetworkLayer 2 Data LinkLayer 1 Physical
Source: http://starter.sdsu.edu/remote/demo/osi-tcp.html
http://starter.sdsu.edu/remote/demo/osi-tcp.htmlhttp://starter.sdsu.edu/remote/demo/osi-tcp.htmlhttp://starter.sdsu.edu/remote/demo/osi-tcp.htmlhttp://starter.sdsu.edu/remote/demo/osi-tcp.html -
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Comparison of ISO-OSI Modeland the DOD (TCP/IP) Model
ApplicationApplicationPresentation
SessionTransport
Host-to-Host
Network InternetData Link
Network AccessPhysical
Source: http://starter.sdsu.edu/remote/demo/osi-tcp.html
http://starter.sdsu.edu/remote/demo/osi-tcp.htmlhttp://starter.sdsu.edu/remote/demo/osi-tcp.htmlhttp://starter.sdsu.edu/remote/demo/osi-tcp.htmlhttp://starter.sdsu.edu/remote/demo/osi-tcp.html -
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Layer Reference to ProtocolRecalled
ApplicationApplication FTP, Telnet, SMTP, HTTP..
PresentationSessionTransport Host-to-Host TCP, UDPNetwork Internet IP, ICMP, IGMPData Link Network
Access Ethernet, Token-Ring ...Physical
Source: http://starter.sdsu.edu/remote/demo/osi-tcp.html
http://starter.sdsu.edu/remote/demo/osi-tcp.htmlhttp://starter.sdsu.edu/remote/demo/osi-tcp.htmlhttp://starter.sdsu.edu/remote/demo/osi-tcp.htmlhttp://starter.sdsu.edu/remote/demo/osi-tcp.html -
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Source: TCP/IP White Paper by Microsoft
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TCP/IP Layers
Network interface layer
Internet layer
Host-to-host transport layer
Application layer
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Layer Properties
In the following slides, the following isdescribed for each layer
Layer function
Core protocols
Relationship to ISO/OSI model
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Network Interface Layer
Responsible for sending and receivingTCP/IP packets on the network medium
(physical/Data Link) Applicable LAN technologies
Ethernet, Token Ring, FDDI etc.
Applicable WAN technologies
X.25 (old), Frame Relay, ATM etc. Note that some technologies such as ATM
and FDDI may be used at both the WAN andthe LAN levels
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Some Core Protocols
IEEE 802.3, IEEE 802.5 and IEEE 802.11series of protocols
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Relationship to OSI Model
Data Link Layer
Physical Layer
Network InterfaceLayer
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Core Internet Layer Protocols
IP A connectionless unreliable protocol that is part of
the TCP/IP protocol suite
ARP (Address Resolution Protocol) Resolves IP addresses to MAC addresses
ICMP (Internet Control Message Protocol)
Diagnostics and error reporting (IGMP) Internet Group Management Protocol
Management of group multicast
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More on Address ResolutionProtocol (ARP)
NIC ID
AA.BB.CC.DD
NIC ID
AB.BD.CD.DE
130.182.190.90 130.182.190.50
Resolves, for example, IP addresses to the corresponding
MAC level hardware address by for instance broadcasting.
IP
HAW
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Relationship to ISO Model
Network Layer Internet Layer
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Transport Layer
Sequencing and transmission of packets
Acknowledgment of receipts
Recovery of packets
Flow control
In essence, it engages in host-to-hosttransportation of data packets and thedelivery of them to the application layer
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Core Protocols of the TransportLayer
TCP(Transmission
Control Protocol)
UDP (UserDatagram Protocol)
Transport Layer
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TCP
Transmission Control Protocol (TCP)
One-to-one and connection-oriented
reliable protocol Used in the accurate transmission of
large amount of data
Slower compared to UDP because ofadditional error checking beingperformed
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UDP
User Datagram Protocol (UDP) One-to-one or one-to-many,connectionless and
unreliable protocol
Used for the transmission of small amount of data Accuracy is not of prime concern The overhead of establishing a TCP connection is not
warranted
Used in video and audio casting
Multicasting Broadcasting
Also used for multimedia transmission Faster compared to TCP
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Relationship to ISO Model
Transport Layerand somefunctions of theSession Layer
Transport Layer
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Application Layer
Provides applications with the ability toaccess the services of the other layers
New protocols and services are alwaysbeing developed in this category
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Some Core Protocols
HTTP
FTP
Telnet
SMTP
POP3 IMAP
SNMP etc.
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End of Module
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Some Application RelatedApplication Layer Protocols
HTTP
FTP
SMTP
Telnet
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Some LAN
Management/Operation RelatedApplication Layer Protocols
DNS
RIP
SNMP
f l
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Hyper Text Transfer Protocol(HTTP)
Protocol relating to web applications
Current version of HTTP 1.1 hasadditional features Upload information to the server
Etc.
Default port number is 80
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File Transfer Protocol (FTP)
File Transfer Protocol Used for downloading from most MP3 sites, for
example
Designed for faster file transfer over theInternet compared to using the HTTPprotocol
FTP sites can be configured alongside a website to support FTP file transfer
FTP default ports are 20 and 21
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Si l M il T f P l
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Simple Mail Transfer Protocol(SMTP)
Governs the transmission of mailmessages and attachments
SMTP is used in the case of outgoingmessages
More powerful protocols such as POP3
and IMAP4 are needed and available tomanage incoming messages
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POP3/IMAP4
Used for incoming mail
POP3 is the older protocol
IMAP4 is the more advanced protocol
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Telnet
Supports terminal emulation or hostsessions
For example, Telnet can be used foraccessing a Unix machine andemulating a terminal attached to the
Unix computer
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R ti I f ti P t l
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Routing Information Protocol(RIP)
Router
Network 1
Network 2
Used by Routers to routedata packets on an IP Internet.
Network 1
Si l N t k M t
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Simple Network ManagementProtocol (SNMP)
Router
Router
RemoteManagement
Console
Switch
Bridge
Facilitates the management of SNMP compliantrouters, bridges, switches etc. by enablingthe collection and exchange of
network management information.
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SNMP
Used by network management utilitiesto manage network devices
For example, a manageable hub thatsupport SNMP can be managed from aremote location using a SNMP based
LAN management software
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Relationship to ISO Model
PresentationLayer
Application Layer
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End of Module
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N. Ganesan, All rights reserved.
Module
TCP/IP Ports and Windows API
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Ports
TCP requires port numbers on the hostand destination for communication
Different port numbers are assigned todifferent protocols by defaultHTTP 80, Telnet 23, FTP 20/21, RPC 135,
NetBIOS 139 etc.
Standard port numbers have beenassigned by the Internet AssignedNumber Authority (IANA)
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Sample TCP Port Numbers
20 FTP Data Channel
21 FTP Control Channel
23 Telnet
80 HTTP on WWW
135 RPC
139 NetBIOS SessionServices
Note: There are port numbers applicable to UDP as well.
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Port Scanning
To test the security of a computer, its portscan be scanned and the port status can bedisplayed
Access Shieldup in www.grc.comto scanyour computers port
Ports
Open is insecure Closedis somewhat secure
Stealthis most secure
http://www.grc.com/http://www.grc.com/ -
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TCP/IP Application Interface
Applications require an ApplicationProgramming Interface (API) to use the
services of TCP/IP
API is a standardized interface between theapplications and the TCP/IP services
Windows Sockets interface and NetBIOSinterface are two of the prominent examplesof Windows API
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WindowsAPI with
TCP/IP
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Windows APIs
Windows socket
Protocol, IP Address and Port number
NetBIOS interface NetBIOS over TCP/IP (NetBT)
Supports NetBIOS Name Management, NetBIOSDatagram and NetBIOS sessions
If support is required for older NetBIOSapplications, then NetBIOS over TCP/IP must beinvoked in the TCP/IP properties tab
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Other References
TCP/IP, MCSE Examcram, Tittel Ed.,Hudson Kurt and Stewart Michael J.,
The Coriolis Group, 1998.
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End of Module
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End of Module
END OF CHAPTER