Earn Money

profileismailbusiness

I want to earn money by completing tasks...

  • 2 years ago
  • 10
files (1)

Handouts-CN-85-117.pdf

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 1

IP Addressing

85

IP Addressing

 An IP address is a numeric identifier assigned to each machine on an IP network.

 Software address, 32-bit long divided into four sections, referred to as octets.

 4.3 billion address space  written in a format known as dotted decimal.  172.16.30.56  The 32-bit IP address is a structured or hierarchical

address.

86

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 2

IP Address Structure

 IP addressing uses two-level (three-level) hierarchical addressing structured by network and host, network, subnet and host.

 The network address uniquely identifies each network segment to which one or more hosts are connected.

 Every machine on the same network shares that network address as part of its IP address.

 In the IP address 172.16.30.56, for example, 172.16 is the network address.

 The node address or host address is assigned to, and uniquely identifies, each machine on a network.

 This part of the address must be unique because it identifies a particular machine—an individual— as opposed to a network, which is a group.

 In the sample IP address 172.16.30.56, the 30.56 is the node address.

87

IP Address Classes

 The designers of the Internet decided to create classes of networks based on network size.

 For the small number of networks possessing a very large number of hosts, they created the rank Class A network.

 At the other extreme is the Class C network, which is reserved for the numerous networks with a small number of hosts.

 The class distinction for networks between very large and very small is predictably called the Class B network.

88

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 3

Class of IP Address – Range 89

90

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 4

91

92

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 5

IPV4 Address 93

Default subnet mask

 A subnet mask is a 32-bit value that allows the recipient of IP packets to distinguish the network ID portion of the IP address from the host ID portion of the IP address.

 The 1s in the subnet mask represent the positions that refer to the network or subnet addresses.

94

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 6

Default subnet mask 95

Special purpose / Reserved IPs

 Some IP addresses are reserved for special purposes- can’t assigned to hosts.

96

Link-local Addresses In case a host is not able to acquire an IP address from the DHCP server and it has not been assigned any IP address manually, the host can assign itself an IP address from a range of reserved Link-local addresses. Link local address ranges from 169.254.0.0 -- 169.254.255.255. These IPs are also not routable.

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 7

97

 Link-local Addresses

 In case a host is not able to acquire an IP address from the DHCP server and it has not been assigned any IP address manually, the host can assign itself an IP address from a range of reserved Link-local addresses. Link local address ranges from 169.254.0.0 -- 169.254.255.255.

 These IPs are also not routable.

Private IPs

 These addresses can be used on a private network, but they’re not routable through the Internet.

 If every host on every network had to have real routable IP addresses, we would have run out of IP addresses.

 By using private IP addresses, ISPs, corporations, and home users only need a relatively tiny group of IP addresses to connect their networks to the Internet.

 This is economical because they can use private IP addresses on their inside networks.

98

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 8

Private IPs 99

• These private addresses are used within an organization or site to allow devices to communicate locally. However, because these addresses do not identify any single company or organization over Internet, therefore, private IPv4 addresses cannot be routed over the Internet.

Network Address Translation (NAT) is required to convert a private IP to real (public) IP.

Network Address Translation 100

 Number of available IPv4 addresses is not enough.

 Due to explosion of the Internet and the increase in home networks and business networks.

 The obvious solution is to redesign the address format to allow for more possible addresses.

 IPv6 – developed, but will take several years to implement because it requires modification of the entire infrastructure of the Internet.

 NAT (RFC 1631) comes to the rescue. Network Address Translation allows a single device, such as a router, to act as an agent between the Internet (or "public network") and a local (or "private") network.

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 9

NAT 101

 NAT combined with private IPv4 addresses has proven to be a useful method of preserving public IPv4 addresses.

 A single, public IPv4 address can be shared by hundreds, even thousands, of devices, each configured with a unique private IPv4 address.

 Without NAT, the exhaustion of the IPv4 address space would have occurred well before the year 2000.

NAT-Enabled Router 102

 NAT-enabled routers can be configured with one or more valid public IPv4 addresses.

 These public addresses are known as the NAT pool. When an internal device sends traffic out of the network, the NAT-enabled router translates the internal IPv4 address of the device to a public address from the NAT pool.

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 10

NAT address types 103

 Addresses used after NAT translations are called global addresses.

 These are usually the public addresses used on the Internet

 Local addresses are the ones we use before NAT translation.

 So, the inside local address is actually the private address of the sending host that’s trying to get to the Internet

104

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 11

105

NAT working 106

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 12

Types of NAT 107

 Static NAT

 Dynamic NAT

 PAT (Port Address Translation)

Static NAT 108

 Static NAT uses a one-to-one mapping of local and global addresses. These mappings are configured by the network administrator and remain constant.

 Basic static NAT configuration: ip nat inside source static 10.1.1.1 170.46.2.2

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 13

Dynamic NAT 109

 Dynamic NAT uses a pool of public addresses and assigns them on a first- come, first-served basis. When an inside device requests access to an outside network, dynamic NAT assigns an available public IPv4 address from the pool.

 Dynamic NAT configuration:

 ip nat pool todd 170.168.2.2 170.168.2.254 netmask 255.255.255.0 ip nat inside source list 1 pool todd

PAT – NAT Overloading

 With PAT, multiple addresses can be mapped to one or to a few addresses because each private address is also tracked by a port number.

 ip nat pool globalnet 170.168.2.1 170.168.2.1

 netmask 255.255.255.0  ip nat inside source list 1

pool globalnet overload

110

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 14

111

Network Address Translation 112

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 15

113

114

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 16

115

116

Subject: Computer Networks 8/16/2024

Subject Teacher: Dr. Adnan Ahmed Arain, Dept. of Cyber Security, QUEST, Nawabshah 17

Who governs the IP Address 117

There are five Regional Internet Registries covering the whole world. They are: •AFRINIC – African Network Information Centre •APNIC -Asia-Pacific Network Information Centre •ARIN – American Registry for Internet Numbers •LACNIC – Latin America and Caribbean Network Information Centre •RIP NCC – Réseaux IP Européens Network Coordination Centre The RIRs are responsible for the allocation and management of IP addresses and AS (Autonomous System) numbers to their respective local internet registries and the internet service provider( ISP). The ISP further assigns the IP addresses to the end-users.