network administration in windows · introduction to tcp/ip • transmission control...

Network

Administration

in Windows

1

Outline

• Chapter I: TCP/IP Protocol

• Chapter II: Building TCP/IP Infrastructure with

Windows Server 2008

• Chapter III: Intranet Application Services:

Web, FTP and Mail

• Chapter IV: Advanced Topics: DFS, NAT,

Security,….

2

3

Chapter I

The TCP/IP Protocol

A Quick Reviews

4

Introduction To TCP/IP

• Transmission Control Protocol/Internet Protocol

(TCP/IP)

– Most commonly used network protocol suite today

– Wide vendor support

– Open protocol

– Provides access to Internet services

• Windows Server 2003/2008/2012

– Can use several protocols

– Many of its main features require the use of TCP/IP

12

The (capital “I”) Internet

▪ The world-wide network of TCP/IP

networks

▪ Different people or organisations own

different parts

▪ Different parts use different technologies

▪ Interconnections between the parts

▪ No central control or management

13

What’s the Internet

• millions of connected computing devices: hosts, end-systems

–PC’s workstations, servers

–PDA’s phones,

• communication links

–fiber, copper, radio, satellite

• routers: forward packets (chunks) of data through network

local ISP

company network

regional ISP

router

workstation server mobile

14

TCP/IP Architecture Overview

• The TCP/IP model can be broken down into four layers: – Application

– Transport

– Internet

– Physical Network Interface

• Application layer provides access to network resources. It defines rules, commands, and procedures for client to talk to a service running on a server

15

TCP/IP Architecture Overview

(continued)

• Transport layer is responsible for preparing data

ready to be transported across the network

• Internet layer is responsible for logical

addressing and routing

• Physical Network Interface layer consists of the

network card driver and the network card itself

16

TCP/IP Protocol

17

The TCP/IP Model

Network layer

PPP ATM Optics ADSL Satellite 3G Ethernet

IP

UDP TCP

HTTP FTP Telnet DNS SMTP Audio Video

RTP

Physical and Data link layer

Application layer

Transport layer

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Layer Interaction:

TCP/IP Model

Host Router Host

Application

TCP or UDP

IP

Link

Physical

IP

Link Link

IP

Link Link

Application

TCP or UDP

IP

Link

Physical Physical

Router

23

A Flow of Application messages across

TCP/IP layers

Messages (UDP) or Streams

(TCP)

Application

Transport

Interne

t

UDP or TCP segment

IP Packets

Network-specific frames

Messag

e Layers

Underlying network

Physical Network interface

24

Encapsulation of a message transmitted

via TCP over an Ethernet

Application message

TCP

header

IP

header

Ethernet header

Ethernet

frame

port

TCP

IP

Segment

Packet

25

Layering: physical communication

application

transport

network

link

physical

application

transport

network

link

physical application

transport

network

link

physical

application

transport

network

link

physical

network

link

physical

data

data

26

Application Layer Protocols • There are many Application layer protocols,

each of which is associated with a client application and service provided by a server (Client/Server Model)

– HTTP

– FTP

– TELNET

– SMTP

– POP3

– IMAP4

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Application Model

28

HTTP

• Hypertext Transfer Protocol (HTTP) is the most common protocol used on the Internet today

• HTTP defines the commands that Web browsers can send and how Web servers are capable of responding

FTP

• File Transfer Protocol (FTP) is file-sharing protocol

• FTP is implemented in stand-alone FTP clients as well as in Web browsers

• It is safe to say that most FTP users today are using Web browsers

Application Layer Protocols

29


TELNET

• Telnet is a terminal emulation protocol that is primarily used to connect remotely to UNIX and Linux Systems

• The Telnet protocol specifies how a telnet server and telnet client communicate

30

SMTP

• Simple Mail Transfer Protocol (SMTP) is used to send

and receive e-mail messages between e-mail servers

that are communicating

• It is used by e-mail client software, such as Outlook

Express, to send messages to the server

• SMTP is never used to retrieve e-mail from a server

when you are reading it

• Other protocols control the reading of e-mail messages


31

POP3

• Post Office Protocol version 3 (POP3) is the most common protocol used for reading e-mail messages

• This protocol has commands to download messages and delete messages from the mail server

• POP3 does not support sending messages

• POP3 supports only a single inbox and does not support multiple folders for storage on the server


32

IMAP4

• Internet Message Access Protocol version 4

(IMAP4) is another common protocol used to

read e-mail messages

• IMAP4 can download message headers only and

allow you to choose which messages to

download

• IMAP4 allows for multiple folders on the server

side to store messages


33

Transport Layer Protocols

• Transport layer protocols (TCP & UDP) are responsible for getting data ready to move across the network

• The most common task performed by Transport layer protocols is breaking entire messages down into segments suitable to form packets

• Transport layer protocols use port numbers

• When a segment is addressed to a particular port, the Transport layer protocol knows to which service to deliver the packet

34

TCP • Transmission Control Protocol (TCP) is the most

commonly used Transport layer protocol for most

Internet services

• TCP is connection-oriented and reliable

• Connection-oriented means that TCP creates and

verifies a connection with a remote host before

sending information

• Verifies that the remote host exists and is willing to

communicate before starting the conversation

• Provides flow control, segmentation, and error

control

35

TCP

• Connection-oriented – Establishes a connection before transmitting data

– Three-way handshake

SYN

SYN/ACK

ACK

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TCP • Error control & Flow control

– Require acknowledgements from receiver to ensure data was received correctly

– Checksum • Unique character string allowing receiving node to

determine if arriving data unit exactly matches data unit sent by source

• Ensures data integrity

Send data, wait for ACK

ACK

Send more data, wait for ACK

37

• Segmentation – Breaking large data units received from Application layer into

multiple smaller units called segments

– Increases data transmission efficiency

– MTU (maximum transmission unit): Largest data unit network

will carry (Ethernet default: 1500 bytes)

• Sequencing – Method of identifying segments belonging to the same

group of subdivided data

• Reassembly – Process of reconstructing segmented data units

TCP

38

Transport Layer (cont’d.)

Figure 2-2 Segmentation and reassembly

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1 2 3 4 5 6 7 8 9 10 11 User Data

1 Source ID or port 16 bits

2 Destination ID or port 16 bits

3 Sequence number 32 bits

4 ACK number 32 bits

5 Header length 4 bits

6 Unused 6 bits

7 Flags 6 bits

8 Flow control 16 bits

9 CRC 16 16 bits

10 Urgent pointer 16 bits

11 Options 16 bits

TCP Segment

40

UDP

• User Datagram Protocol (UDP)

– Not as commonly used as TCP

– Used for different services

– Connectionless and unreliable

• UDP is the appropriate if

– Unconcerned about missing packets

– Want to implement reliability in a special way

• Streaming audio and video are in this category

41

UDP – Segment

1 2 3 4 User Data

1 Source ID or port

2 Destination ID or port

3 Length

4 Checksum

42

TCP versus UDP

• TCP is connection-oriented and reliable

– Like registered mail

• UDP is connectionless and unreliable

– Like sending a message split on several

postcards and assuming that the receiver

will be able to put the message together

43

Sockets and Ports

44

Sockets and Ports • Processes assigned unique port numbers

• Process’s socket – Port number plus host machine’s IP address

• Port numbers – Simplify TCP/IP communications

– Ensures data transmitted correctly to the specific application among multiple applications running on same host

• Example – Telnet port number: 23

– IPv4 host address: 10.43.3.87

– Socket address: 10.43.3.87:23

45

Sockets and Ports (cont’d.)

Figure 4-12 A virtual connection for the Telnet service

46

Sockets and Ports (cont’d.) • Port number range: 0 to 65535

• Three types

– Well Known Ports

• Range: 0 to 1023

• Operating system or administrator use

– Registered Ports

• Range: 1024 to 49151

• Network users, processes with no special privileges

– Dynamic and/or Private Ports

• Range: 49152 through 65535

• No restrictions

47

Sockets and Ports (cont’d.)

Table 4-3 Commonly used TCP/IP port numbers

48

Internet Layer Protocols

• Internet layer protocols are responsible for all tasks related to logical addressing

• An IP address is a logical address

• Any protocol that is aware of other networks exists at this layer

• Each Internet layer protocol is very specialized

• They include: IP, RIP and OSPF, ICMP, IGMP, and ARP

49

IP

• Internet Protocol (IP) is responsible for the logical

addressing of each packet created by the Transport

layer to produce a complete IP Packet

• As each packet is built, IP adds the source and

destination IP address to the IP packet

ICMP

• Internet Control Messaging Protocol (ICMP) is used

to send IP error and control messages between

routers and hosts

• The most common use of ICMP is the ping utility


50

IP Packet version 4

1 Version number 4 bits

2 Header length 4 bits

3 Type of Service 8 bits

4 Total length 16 bits

5 Identifiers 16 bits

6 Flags 3 bits

7 Packet offset 13 bits

8 Hop limit 8 bits

9 Protocol 8 bits

10 CRC 16 16 bits

11 Source address 32 bits

12 Destination Address 32 bits

13 Options varies

14 User data varies

1 2 3 4 5 6 7 8 9 10 11

IP4

12 13 14

51

IGMP

• Internet Group Management Protocol (IGMP) is used

for the management of multicast groups

• Hosts use IGMP to inform routers of their

membership in multicast groups

• Routers use IGMP to announce that their networks

have members in particular multicast groups

• The use of IGMP allows multicast packets to be

distributed only to routers that have interested hosts

connected


52

ARP

• Address Resolution Protocol (ARP) is used to

convert logical IP addresses to physical MAC

addresses

• This is an essential part of the packet delivery

process


53

Network Interface Layer

Protocols

• Most of the common Network Interface layer

protocols are defined by the Institute of Electrical

and Electronics Engineers (IEEE)

54

Types of addresses used on hosts

Address Example Software Example Address

Application Layer Web browser www.cba.uga.edu

Transport Layer TCP 80

Network Layer IP 128.192.98.5

Data Link Layer Ethernet Driver 00-0C-00-F5-03-5A

http://www.cba.uga.edu/

55

• Internet Protocol (IP):

– a protocol used in the internet layer.

– IP makes use of the existing networks to deliver information, where these networks may use a variety of protocols.

• Each computer has two addresses:

– hardware address: used by the underlying network protocol for deliver data frame;

– IP address: used by the internetworking protocols for deliver IP Packet.

• Hardware address is also known as physical address.

IP Addresses

56

IP Addressing Scheme • Each computer / router is assigned a unique IP address

having 32 bits.

• Each IP address has two parts:

– The prefix (network ID or NetID) specifies the network to which the computer is attached.

– The suffix (HostID) specifies a particular computer on a network.

• Problem

– Given only 32 bits, how many bits should be allocated to the prefix and the suffix?

• around 4 billion addresses.

IP Addresses

57

IP Addressing Scheme • Considerations

– If the prefix has many bits (large prefix, small

suffix), there are many networks you can built but

each network can only have a few computers.

– If the prefix has a few bits (small prefix, large

suffix), there are only few networks you can built

but each network can have many computers.

IP Addresses

58

Subnet Masks

• A subnet mask defines which part of its IP address is the network ID and which part is the host ID

• Subnet masks are composed of four octets just like an IP address

• Wherever there is a 255 in the subnet mask, that octet is part of the network ID

• Wherever there is a 0 in the subnet mask, that octet is part of the host ID

59

Subnet Masks (continued) • A computer uses its subnet mask to determine

– Which network it is on

– Whether other computers are on the same

network or a different network

• If two computers on the same network are

communicating, then they can deliver packets

directly to each other

• If two computers are on different networks,

they must use a router to communicate

60

Subnet Masks (continued)

61

• The IP addressing scheme defines three primary classes (A,B,C), where each class has a distinct prefix/suffix size, and two reserved classes (D&E).

• The internet can accommodate large networks, medium networks, and small networks.

• Classes A, B, C are the primary classes. The IP addresses of computers and routers belong to these classes.

• Class D is used for multicasting. When a packet is sent to an IP multicast address, all the computers sharing this address will receive this packet.

• Class E addresses are considered experimental and are not used

IP Address Classes

62

The Classful Addressing Scheme

63

• The first decimal value defines the

class of the IP address as follows:

64

IP Address Classes & Default

Subnet Masks

65

• In each primary class, the number of networks

and the number of computers per network are as

follows:

• Each packet sent across the internet contains:

– the IP address of the source, and

– the IP address of the destination.

66

• Dotted Decimal Notation – Commonly we use the dotted decimal notation to

represent the 32-bit IP address.

• more convenient for human to manipulate

– Each octet (8-bit) is expressed as a decimal value, and adjacent decimal values are separated by a dot.

– Example:

67

• Loopback address

– 127.x.x.x

– intended for use in testing TCP/IP and for inter-process communication on the local computer

• Other special value of primary classes:

68

Assigning Public IP Addresses • Assigning Prefix Address

– Each network must have a unique prefix address throughout

an internet.

– To connect a network to the global internet, an organization

obtains a unique prefix address from the Internet Service

Provider (ISP).

– In turn, the ISP coordinates with a central organization (the

Internet Assigned Number Authority (IANA, on or before

1998); the Internet Corporation for Assigned Names and

Numbers (ICANN, after 1998)) to ensure the uniqueness of

the prefix.

– To connect a network to a private internet (Intranet), the

organization can determine the prefix while ensuring its

uniqueness.

69

Assigning IP Addresses • Assigning Suffix Address

– Each computer must have a unique suffix address in the same network; while two computers in two different networks can have identical suffix address or HostID.

– If the suffix is 00…0 or 11…1, the corresponding IP addresses have special meaning. Do not assign these suffixes.

• An IP address with suffix equal to 00…0 is used to refer to the network itself.

• An IP address with suffix equal to 11…1 is a directed broadcast address, i.e., it refers to all hosts on the network.

70

• Example

– An organization wants to form a private TCP/IP

internet with four networks, where one network is large

(with many computers), two are medium, and one is

small.

– Firstly, assign a unique prefix to each network:

• Assign a class A prefix for the large network (say, 10).

• Assign a class B prefix for each of the two medium networks

(say, 128.10 and 128.11).

• Assign a class C prefix for the small network (say, 192.5.48).

– Secondly, assign a unique suffix to each computer

within each network:

72

Private IP Addresses

• You can use these addresses on any private LAN.

• You CANNOT use them on the internet. • Internet routers will block them.

73

Default Gateway

• Default gateway is another term for router

• If a computer does not know how to deliver a

packet, it gives the packet to the default

gateway to deliver

• Routers can distinguish multiple networks and

how to move packets between them

• Routers can also figure out the best path to

use to move a packet between different

networks

74

Classful IP Address

▪ A classful network had a “natural” or “implied”

prefix length or netmask: ▪ Class A: prefix length /8 (netmask 255.0.0.0)

▪ Class B: prefix length /16 (netmask 255.255.0.0)

▪ Class C: prefix length /24 (netmask 255.255.255.0)

▪ Modern (classless) routing systems have explicit

prefix lengths or netmasks

▪ You can't just look at an IP address to tell what the prefix

length or netmask should be. Protocols and

configurations need explicit netmask or prefix length.

75

Classless addressing

▪ Internet routing and address management

today is classless

▪ CIDR = Classless Inter-Domain Routing

▪ routing does not assume that class A, B, C

implies prefix length /8, /16, /24

▪ An ISP gets a large block of addresses

▪ e.g., a /16 prefix, or 65536 separate addresses

76

Classless addressing

• Allocate smaller blocks to customers

– e.g., a /26 prefix (64 addresses) to 4 customers

for their medium public networks, a /28 prefix (16

addresses) to 32 customers for their medium

public networks, and a /29 prefix (8 addresses) to

another 64 customers for their small public

networks (and some space left over for other

customers)

77

Binary presentation of Classless IP

▪ 137.158.128.0/17 (netmask 255.255.128.0)

▪ 198.134.0.0/16 (netmask 255.255.0.0)

▪ 205.37.193.128/26 (netmask 255.255.255.192)

1000 1001 1001 1110 1 000 0000 0000 0000

1111 1111 1111 1111 1 000 0000 0000 0000

1100 0110 1000 0110 0000 0000 0000 0000

1111 1111 1111 1111 0000 0000 0000 0000

1100 1101 0010 0101 1100 0001 10 00 0000

1111 1111 1111 1111 1111 1111 11 00 0000

78

Classless addressing exercise

• Consider the address block 133.27.162.0/28

and 133.27.163.48/29.

▪ What are the IP addresses range can you

obtain from each block?

▪ in prefix length notation

▪ netmasks in decimal

▪ IP address ranges

▪ What blocks are still available (not yet

allocated)?

network administration in windows · introduction to tcp/ip • transmission control...

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