Introduction to Network Security

Why Need Security ?

1. There is a lot information in our computer
2. These data are store in text file &/@ database
3. Security is needed to against unauthorized parties

Security Fundamental Principal

CIA

  C-confidentiality
   I-integriti
  A-availability

Type of Attack

1. Interruption: somehow disrupt the service being provided by the network
2. Interception: eavesdrop on communication meant to be private @ confidental
3. Modification: tamper with information @ network resourses
4. Fabrication: counterfeit information @ network resources @ services are inserted into the network            

TCP/IP (Transmission Control Protocol/Internet Protocol)

About TCP/IP


-  is the basic communication language or protocol of the Internet. 
- also be used as a communications protocol in a private network (either an intranet @ extranet).
- TCP/IP is a two-layer program. 

1. The higher layer: manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message.
2. The lower layer: Internet Protocol handles the address part of each packet so that it gets to the right destination.

- TCP/IP uses the client/server model of communication in which a computer user (a client) requests and is provided a service (such as sending a Web page) by another computer (a server) in the network.

-  TCP/IP communication is primarily point-to-point, meaning each communication is from one point (or host computer) in the network to another point or host computer.

OSI Layer

IP Address


 - An IP Address, or Internet Protocol is a form of numerical identification.
 - is a unique address.
 - divided into two: IPV4 & IPV6

• IP Terminalogy

               bit: combination no. 0 & 1

           byte: scale between 7 bit & 8 bit

           octet: always 8 bit

• Class of IP Address (Genaral for WAN)

                class A:  for very large networks  [ 1-126 ]

                class B: used for medium-sized  network [ 128-191 ]

                class C: commonly used for small to mid-size businesess [ 192-223 ]

                class D: reserved

                class E: used for experimental purposes only

                * 127 is for loopback @ localhost

• Private IP Address ( used for VLAN )

                 classs A: 10.0.0.0 - 10.255.255.255.255

             class B: 172.16.0.0 - 172.31.255.255

             class C: 192.168.0.0 - 192.168.255.255

            * how to know/check IP Address  ?

                       First step :  

                                                                                

                                                                                                       

                                                                                                           




Static IP Address: assign by IT administrator


Dynamic IP Address: assign by "DHCP" server


Subnetmask

• similar to IP address
• have 4 octet
• use to identify host id & network id
• class A ( 1 net, 4 host )
• class B ( 2 net, 2 host )
• class C ( 3 net, 1 host )

Network address: 1st address


Broadcast address: last address




**THIS IS INCOMPLETE NOTES !!!!! I WILL PROCESS IT AS SOON AS POSSIBLE

Basic Data Communication

Data = raw material, information


Components Data Communication

1. sender
2. receiver
3. protocol
4. medium@ media (e.g: utp, stp, bluetooth. infrared)
5. message (e.g: text, image, audio, video, graphic & etc)
6. equipment (e.g: computer, router, modem, switch & etc)

Network Topology

1. ring topology
2. mesh topology
3. star topology
4. bus topology
5. hybrid topology
6. tree topology

Type of Network

LAN(Local Area Network)

  -connects network devices over a relatively short distance

MAN(Metropolotan Area Network)

  -a network spanning a physical area larger than a LAN but smaller than a WAN, such as a city.

WAN(Wide Area Network)

  - spans a large physical distance. The Internet is the largest WAN, spanning the Earth.