Week-13 (Lecture-1) Data Communication Hardware: 1)Coaxial cable: Widely installed for use in business and corporation Ethernet Used to install LANs. Consists of inter copper insulator covered by cladding material Cladding material covered by an outer jacket Inner conductor insulating material Outer conductor sheath material ApplicationsTransmission characteristics TV distribution (cable TV) telephone transmission Short run computer system Local area networks transmit analog and digital signals analog signaling is about 400 Mhz less than 1 Km distance (Amplifier needed) Operation of 100’s Mb/s over 1 Km

Week-13 (Lecture-1) 2) Twisted Pair Cables: Each wire with copper conductor Separately insulated wires Twisted together to reduce cross talk Often bundled into cables of two or four twisted pairs ApplicationsTransmission characteristics Common in building used at speed of 10’s Mb/s (CAT3) and 100Mb/s (CAT5) over 100s meters. Common for telephone line at home and office buildings If enclosed in a sheath It is shielded twisted pair (STP) often for home usage Must be shield from voltage lines

Week-13 (Lecture-1) 3) Optical Fibers: Plastic core of optical fiber (2 to 125 μm) Cladding is an insulating material Jacket is a protective cover Laser or light emitting diode for transmission. ApplicationsTransmission characteristics Long distance telecommunication Greater capacity (2 Gb/s over 10’s of Km) Smaller size and lighter weight Lower attenuation (reduction in strength of signal) Electromagnetic isolation (not effected by external electromagnetic) Greater repeater spacing (fewer repeaters, reduces line regeneration cost)

Week-13 (Lecture-1) Computer Security: Computer Security can be categories into 4 different parts i.e. 1.Data Security 2.Information Security 3.Network Security 4.Standalone Computer Security

Week-13 (Lecture-1) 1. Data Security: It depends on the following factors: Data Integrity: Data should be related and unique. Data Availability: Data should be available in a correct form. Data Atomicity: Data should be consistent (not in a worst form) 2. Information security: It depends on the following factors Information Authorization: Information is disclosed on only authorized persons Information integrity: Information is complete, accurate and protected against unauthorized access. Information availability: Information is available and usable when required. Information authenticity: Business transaction as well information.

Week-13 (Lecture-1) 3- Network security: Types of Network Security Devices Active Devices: These security devices block the surplus traffic. Firewalls, antivirus scanning devices Ex. content filtering devices Passive Devices: These devices identify and report on unwanted traffic Ex. intrusion detection appliances. Preventative Devices: These devices scan the networks and identify potential security problems. Ex. penetration testing devices and vulnerability assessment appliances.

Week-13 (Lecture-1) 4- Standalone computer security: Security issues in a standalone computer: Malware: Short form of malicious s/w design to cause damaged to a standalone computer. Affected areas- - system’s boot sector - data files - installed s/w - BIOS (Basic Input Output System) Unauthorized access: Gain access to other’s computer to steal or modify the data. Method used- - Password hacking Security management: Intrusion detection system Monitor the events in a computer system. Ex. Masquerader, Misfeasor, Clandestine user.

Week-13 (Lecture-1) Firewall: A network security system that manages and regulates the network traffic based on some protocols A firewall establishes a barrier between a trusted internal network and the internet. Firewalls exist both as software that run on a hardware and as hardware appliances. Mostly used for threats from the internet. Many routers that pass data between networks contain firewall components and conversely, many firewalls can perform basic routing functions. Types of firewalls: 1.Packet filters 2. Circuit-level gateways 3. Application-level gateways