Network 4 - Lecture notes 4 PDF

Preview

Summary

CSIS 2270 Jim-mee Ng...

Description

2017-02-04

IPv4

Understanding Internet Protocol

• As a network administrator, you will use the Transmission Control Protocol/Internet Protocol (TCP/IP) communications protocol suite most often. • te to ve sio or is the most frequently used mm icatio s to IP resides on the network layer of the OSI model.

IP Addresses

IP Addresses

• IP addresses consist of four numbers, each being a 8-bit word, with a value between 0 and 255. • Examples include:

ddress is formed by a w k • An a • A subn subnet et ma mask sk is used to identify the mbe bi sed the two k .

– 208.32.56.232 – 192.168.3.54 – 12.5.24.2

• To a

to th ter ddress and

and

t, you will also need ddre .

• Binary format 11000000.10101000.00000101.00000011

Classfu Network Architecture • The IPv4 classification system is known as the classful network architecture and is broken down into five classes, three of which are commonly used by hosts on networks— Classes A, B, and C. • The term node is synonymous with “host.” • If an IP address is Class A, the first octet is considered to be the “network” portion.

Classfu Network Architecture

2,097,152

Cl Class ass A B C D E

Lea Leading ding bits 0 10 110 1110 1111

1

2017-02-04

Exploring the Components of an IPv4 address • Classful IP addresses

Network ID and Host ID • Separating network ID and host ID

Class A Address Range 0 to 127 SM 255.0.0.0

0

10

(8 Bits) 110 7

8

Exploring the Components of an IPv4 address • What’s wrong with this picture?

Network ID and Host ID • Separating network ID and host ID

9

10

Loopback Testing

Usable Addresses

• The range for Class A is 0–127. • The 127 network number isn’t used by hosts as a lo logical gical IP address address. Instead, this network is used for , which allow for testing.

•

is always going to be .

• The first and last addresses can’t be used. –

– E.g. pi ping ng 127 127.0.0.1 .0.0.1

(in binary) for the .

defines the

•172.24.0.0 (the net id of a class B network)

–

(in binary) defines the known as the , •172.24.255.255 (broadcast a message in the network 172.24.0.0)

2

2017-02-04

Class D and E

Decima t Binary Conversion

• Class D and Class E are not used by regular hosts. – lass is used for what is known as m as — transmitting data to multiple computers (or routers). •All computers belonging to a m ul ulticast ticast grou group p

– Class E was reserved for future use, but this has given way to IPv6 instead.

Exploring an IPv4 Address in Binary • Understanding the bits of an IP address

Calculator

16

Exploring an IPv4 Address in Binary

IPv4 properties using a Class A IP address

• Binary values

17

3

2017-02-04

IP Conflict

Public and Private Addresses

• Furthermore, it is important to avoid an IP co conflic nflic nflictt. • conflicts occur when tw com ute s are configured ith the sam add

• IPv4 addresses are further classified as either public or private. blic ddre s tha xp sed to the te – Any other computers on the Internet can potentially communicate with them.

•

ivat te

ddress s d ther

hidde two ks.

m the

– They are usually behind an IP proxy or firewall device.

Private IP Addresses and NAT

APIPA • APIPA is an acronym for Automatic Private IP Addressing. • It uses a single Class B network number: 169.254.0.0. – IP address range is 169.254.0.1 through 169.254.255.254 • If a Windows client cannot get an IP address from a DHCP server and has not been configured statically, it will auto-assign a number on this network.

as A—10.0.0.0 to 10.255.255.255 as B—172.16.0.0 to 172.31.255.255 as C—192.168.0.0 to 192.168.255.2

These address type must be translated by a Network Address Translation (NAT) process on a server or router to Pubic IP addresses for Internet Access 21

Static and Dynamic Addresses

Static Addresses

• Static IP address are addresses that are manually assigned to a host.

• Dynamic IP addresses are more common than static IP addresses, whereas they automatically obtain an IP address (and other IP information) from a DH DHCP CP Serv Server er er. – Dynamic Host Configuration Protocol (DHCP)

4

2017-02-04

DHCP Operations

Understanding DHCP

25

Default Gateway and DNS Server

26

Default Gateway and DNS Server

• To have a fully functional computer, however, we also need to configure two more fields. – Default gateway - The first IP address of the device that a client computer will look for when attempting to gain access outside the local network. – –

Exploring the Components of an IPv4 address

Exploring the Components of an IPv4 address • Determining local and remote addresses

• Identifying the default gateway

255.0.0.0

29

255.0.0.0

30

5

2017-02-04

Network Address Translation

Network Address Translation

• Network address translation or NAT is the process of modifying an IP address while it is in transit across a router, computer, or similar device. • This is usually so one larger address space (private) can be re-mapped to another address space, or perhaps re-mapped to a single public IP address. • However, more advanced routers allow for port address translation (PAT), a subset of NAT, which translates both IP addresses and port numbers.

Network Address Translation

Subnetting • Subnetting is the subdivision of your logical IP network • By default, all computers are on one subnet or network with no divisions involved. • By modifying the default subnet mask, you can subnet your network into multiple smaller networks.

Subnetting

Subnetting

• Note: – All 0’s and all 1’s cannot be used as subnet address and host address

• For example: For a class C address, if 3 bits are used for subnetting – Subnet mask: 255.255.255.224 •(last 8 bits: 1110 0000)

– No. of subnets: 23 – 2 = 6 – No. of hosts per subnet: 25 – 2 = 30

• Example on the next page assumes using a class C address 192.168.1.0/28 (i.e. 4 bits for subnetting)

6

2017-02-04

Subnetting

Subnetting

Classless Inte Domain Routing (CIDR)

CIDR Notation

• Classful address has a problem of not fully utilizing all addresses available

• CIDR specifies an IP address range using a combination of an IP address and its associated network mask. xxx.xxx.xxx.xxx/n

– E.g. a class B address allows 216 – 2 = 65534 hosts

• CIDR is based on variable-length subnet masking (VLSM)

– where n is the number of (leftmost) '1' bits in the mask.

• For example,192.168.12.0/23 – applies the network mask 255.255.254.0 to the 192.168 network, starting at 192.168.12.0. – This notation represents the address range 192.168.12.1 - 192.168.13.254.

Subnetting IPv4

Subnetting IPv4 • A single class C network

• Creating subnets

2 7 (128) 2 6 (64) Subnet Value 0 0 192.168.1.0

41

Four IP Ranges 192.168.1.1-62

0

1

192.168.1.64

1

0

192.168.1.128 192.168.1.129-190

1

1

192.168.1.192 192.168.1.193-254

192.168.1.65-126

42

7

2017-02-04

Subnetting IPv4

Subnetting IPv4 • A subnetted network

• Subnetting with two high-order bits

192.168.1.65 to 192.168.1.126

192.168.1.129 to 192.168.1.190 43

Subnetting IPv4 • Determining the number of subnets and hosts in a Class C network

44

Subnetting IPv4 • Applying Subnetting Knowledge

00

45

Subnetting IPv4 • Applying Subnetting Knowledge

46

Subnetting IPv4 • What’s wrong with this picture?

01

01

47

48

8

2017-02-04

IPv6

IPv6 Addresses

• IPv6 is the new generation of IP addressing for the Internet, but it can also be used in small office networks and home networks. • It was designed to overcome the limitations of IPv4, including address space and security. • IPv6 is a 128-bit system, whereas its still-dominant predecessor IPv4 is only a 32-bit system. – IPv4 can have approximately 4 billion IP addresses in the whole system – IPv6 can have 340 undecillion addresses. That’s 340 with 36 zeroes after it!

• Un Unicast icast address address: A single address on a single interface. • There are two types of unicast addresses.

IPv6 Addresses

IPv6 Addresses

Anyca ca cast st addr address ess ess: These are addresses assigned to • Any a group of interfaces, most likely on separate hosts. – Packets that are sent to these addresses are delivered to only one of the interfaces— generally, the first one, or closest, available. Multt icast add addres res resss: These addresses are also • Mul assigned to a group of interfaces and are also most likely on separate hosts, but packets sent to such an address are delivered to all of the interfaces in the group.

• IPv6 addresses are broken down into three parts:

IPv6 Addresses

– Global unicast addresses are routable and displayed directly to the Internet. •These addresses start at the 2000 range. •First 48 bits specifies the network address

– Link local address, which are autoconfigured and are used to connect to local devices •First 10 bits are 1111111010 (fe80 /10)

– Global routing prefix: This is the first three groups of numbers (48 bits), and it defines the “network” of the address. – IPv6 subnet: This defines the individual subnet of the network that the address is located on. – Interface ID: This is the individual host IP portion. It can be assigned to one interface or more than one interface, depending on the type of IPv6 address.

Understanding Hexadecimal

20 2001: 01: 01:4860:0000:200 4860:0000:200 4860:0000:2001:0000:00 1:0000:00 1:0000:0000:0000:0068 00:0000:0068

54

9

2017-02-04

Displaying IPv6 Addresses

IPv6 Addresses

• Hexadecimal • Zero compression • Dropping leading zeros

55

IPConfig /All Command

Testing IPv6 Loopback

Testing Anothe omputer’s IPv6 Lin Loca ddress

Pinging ipv6.google.com

10

2017-02-04

Dual IP Stack

IPv Mapped Addresses

• A dual IP st stac ac ack k exists when there are two Internet Protocol software implementations in an operating system, one for IPv4 and another for IPv6. • Dual stack IP hosts can run IPv4 and IPv6 independently, or they can use a hybrid implementation, which is the most commonly used method for modern operating systems.

• IPv4-mapped addresses have the first 80 bits set to 0 (note the double colon), the next 16 set to 1 (shown as ffff), and the last 32 bits populated by the IPv4 address.

IPv4 to IPv6 Tunneling

Summary

• IPv6 packets can be encapsulated inside IPv4 datagrams. • In Microsoft operating systems, this is generally done with the Teredo adapter, which is a virtual adapter or “pseudointerface,” not a physical network adapter. An example of one of these addresses would be: Fe Fe80::5e 80::5e 80::5efe:10.0.0.2%2 fe:10.0.0.2%2

• How to categorize IPv4 addresses using classifications such as Class A, B, and C. • What the default gateway and DNS server are and how to configure them within a network adapter’s TCP/IP properties dialog box. • How to define advanced TCP/IP concepts, such as NAT and subnetting, and how to create a subnetted network.

• These addresses look like IPv6 addresses, other than the last 32 bits, which are written in the customary dot-decimal notation. • Pv4-mapped IPv6 address for the IPv4 address 10.254.254.1 is ::ffff:10.254.254.1

Summary • How to define CIDR. • The basics of IPv6 and how to configure IPv6 in the command line. • How to define IPv6 dual stack and tunneling technologies.

11...