Data and network security MIT Notes

CIA model (Confidentialy ,Integrity & Availability)

• Confidentialy: security focus, means information is not available for unauthorized access
• Integrity: accuracy & completeness focus, means information is not modified by unauthorized access
• Availability: availabilty focus, means data is available when authorized access

Attack Process (MOM)

• Mehod:
  • Ability: if wifi security is wep, it can be hacked
  • Information: some weekness, ie free internet use
  • Tools: by using tools
• Oppurtunity: work for some time& access ie we now by default wifi has 12345678 password so we can use it
• Motive: fun,finance,penteration (testing) ,etc

Types of attack

• Active: to alter system resourses
  • Masqurade attack: use fake identity to gain unauthorized access
  • DOS attack: atack an system to provoide its services to its users
• Passive: to learn for system but not effect the system
  • Traffic Analysis: Read whole trafic
  • Release of message: specific data read ie alert (beep) when ATM byte received

Defence methods

• Physical control ie use locker
• Hardware control use biometric for open system
• Software control use password
• Encription ie use A ? D +2

Network security

• Cryptography: use data conversion ie represent Rizwan as u98ujl
• Stengnography use data hiding ie hide rizwan to an image
•  

Encriptions

• DES: attach image here
• AES: attach image here

Website hacking

• Cross site scripting: in message add html,js code
• SQL Injection: wrong sql queries
• Remote file Inclusion: Shell code to access web server
• DDOS: block access of a website
• Broute fource: all possible combination to access

Internet security

• Layers: secure your layers (network, transport,application etc)

SIR USAMA

Subnetting

• Logical subdivision of IP (host portion) is called subnetting
• IP ? Network+hosts/routingPrefix(CIDR) ie 192.168.1.0/24 24 bits for network and 8 bits for hosts
• each subnet must have unique CIDR, if same Router can't communicate with subnets
• ie 192.168.1.0/24 to 192.168.1.220/24 communication done because no subnet maked
• 192.168.1.19/25 is a network, 192.168.1.220/24 is other network, we need router
• USE of subnetting: Save addresses
• Classfull vs classless subnets

• VLSM (variable length subnet mask) each subnet has different sized of hosts
• FLSM (fixed length subnet mask) each subnet have same no of ip's
• Mininum no of hosts for class c ip address? 192.168.1.0/30 means 30 bits for network and 2 for hosts 22=4 one for network, one for subnet mask, and two hosts
• Max no of hosts for class c ip address? 28-2 , excluded 2 are subnet mask and network

  Class	Max hosts	Min hosts	Range	Stat	Binary
  A	224-2	224-222-2	0-127	N.H.H.H	00000000 - 01111111
  B	216-2	216-214-2	128-191	N.N.H.H	10000000 - 10111111
  C	28-2	28-26-2	192-223	N.N.N.H	11000000 - 11011111
  D			224-239	for multicast	11100000 - 11101111
  E			240-255	for experiments	11110000 - 11111111

An example, we need 4 networkd using VLSM

How to find prefix

192.168.1.100/?

1. 26=64 and 27=128 we now 64<100<128
2. 27 so 32-7=25 is prefix
3. 192.168.1.100/25

Available subnets

for class C

1. 192.168.1.1/24 2CDIR-24 as 224-24=20=1 only one subnet
2. 192.168.1.122/26 Find 2CDIR-24 as 226-24=22=4 four subnet

Subnetting

1. convert ip address into binary
2. check class of ip address and write binary of class
3. Multiply both ip address bits and save the result
4. Now depends on how many branches needs, make bits ie if 6 branches then 23=8
5. assign first group of bits to left side of binary (red part)
6. make subnets for 172.172.172,172 for 6 branches

TCP/IP layers

1. Application layer:messages + programs interfaces use this (application +prsentation+session) ie http,ftp etc
2. transport layer: add headers and connection status, ie port numbers
3. network layer: ip address, use Router
4. datalink layer: use mac address on switch
5. physical layer: binary maked to travel on wires
6. Every card (Bluetooth ,wifi) has its individual mac address A pc use all 5 layers so it can be maked router or switch

Switching

Networks

• broadcast: send info one to all other i.e send sms to all world
• multicast: send one to more than one ie group sms
• unicast: sned info one to one ie chat with friend
• anycast: used in routers?

Bus topology

• Wired: CSMA/CD?

Network Cores

Network Edges

end points,ie Sender & receiver for example ATM,

Network Cores:

Intermediat devices amoung edges ie switch,hub,router.

Circut switching:

Communication that have dedicated link

packet switching

use shared link for communication

Physical communication

That use network (IP) + datalink (mac) + physical layer.

Logical communication

that uses transport (for port) & application layer (for url).

To send email following protocols used

SMTP ? FTP ? TCP/UDP ? IP

Data link layer connectives

Upper:Logical Link control (LLC) Lower:Media access control (MAC)

Gateway

a device used to connect two different networks, especially a connection to the Internet.