COMPUTER NETWORKSCOMPUTER NETWORKS

PREVIEWPREVIEW

What is Networking.Imp Terms.Types of Networks.LAN/MAN/WANTopologies.

COMPUTER NETWORKCOMPUTER NETWORK

A COLLECTION OF CMPTRS INTER-

CONNECTED WITH THE HELP OF A MEDIA

(WIRE,OFC,SATL etc..) IN SUCH A WAY

THAT EXCHANGE OF DATA/INFO TAKES

PLACE.

ADVANTAGES OF NETWORKING• COMN

• RELATIVE PRICE OF CMPTRS VS COMN.

• SHARING OF INFO

• SHARING OF RESOURCES

• SHARING OF APPLNS/PGMES• HIGH RELIABILITY.• IMPROVED COMNS (MAILING).• WEB SERVICES.• DATA SERVICES AND MAINT

CENTRALIZED

IMP TERMSIMP TERMS

Bandwidth. The amount of data that can be transmitted in a fixed amount of time.

Broadband. A type of data transmission in which a single medium (wire) can carry several channels at once. Cable TV, for example, uses broadband transmission.

IMP TERMSIMP TERMS

Domain. A gp of networked computer that share a single Security Accounts Manager (SAM).

Fiber Optic. A type of network

cable that uses a central glass or

plastic core surrounded by a

plastic coating.

Protocol. A predefined set of rules that dictates how cmptrs or devices communicate and exchange data on the network.

Firewall. A combination of hardware and software that protect a network from attack by hackers that could gain access through public networks, incl the Internet.

IMP TERMSIMP TERMS

Gateway. The hardware and software needed to connect two separate network environment so that comn can occur.

TCP/IP (Txn Control Protocol/Internet Protocol) Address An address used by the Internet Protocol that identifies the device's loc on the network.

IMP TERMSIMP TERMS

Ping. A TCP/IP utility used to test whether another host is reachable. An request is sent to the host, who responds with a reply if it is reachable. The request timed out if the host is not reachable.

Server. A computer that provides resources to the clients on the network.

IMP TERMSIMP TERMS

TYPES OF NETWORKS

• SERVER BASED (SERVER TO CLIENT) Contain clients and the servers that support them.

• PEER TO PEER Has no server and uses the network to share resources among indep peers.

• HYBRID NETWORK. A client–server network that also has peers sharing resources. Most net works are actually hybrid networks.

WINDOWS NETWORK OS

Windows NT(New Technology)

Windows 2000 Server

Windows 2000 Advanced Server

Windows 2003 Server (Standard,

Enterprise Editions)

CLIENT-SERVERFILE SERVERCLIENTSNETWK OS IN FILE SERVER.CLIENTS HAVE THEIR OWN OS.CENTRALISED SERVICES—

SECURITY,AND etc..

CLIENT-SERVER

Advantages Strong central security.

Central file storage.

Eqpt sharing.

Dedicated, faster than peer to peer

Easy manageability of large No of cmptrs.

DisadvantageDisadvantage Expensive Dedicated

Hardware.

Expensive network operating system and client license.

A dedicated network administrator reqd.

PEER TO PEER

NO NETWK OS. EACH MACHINE HAS OS.

INDEP MACHINES PHYSICALLY CONNECTED TO EACH OTHER.

RESOURCES ARE SHARED AMONG EQUALS.

NO CENTRAL CONTROLLING AUTH.

ALL MACHINES HAVE EQUAL RIGHTS.

GIVES SHARE LEVEL SECURITY.

PEER TO PEER Advantages No extra investment in

server HW and SW reqd.

Easy setup.

No network Admin reqd.

Lower cost for small network.

Sharing allowed.

DisadvantagesDisadvantages Inability of peers to

handle many NW connections as servers.

No central pt for file storing.

Admin for all cmptrs.

Weak security.

Lack of management which makes large peer networks hard to work.

HYBRID NETWORKS Advantages

• Advantages of server based networking .

• Many of the advantages of peer based NW.

• Ability of users and network administrators to control security based on the imp of the shared resources.

DisadvantageDisadvantage

• Hybrid computing shares the disadvantages of server based NW.

• Expensive Dedicated Hardware.

• Expensive network operating system and client license.

• A dedicated network administrator reqd.

APPLICATIONS OF NETWORKING

• E MAIL

• E CHAT

• VIDEO CONFERENCE

• FILE TFR

• INTERNET

PRE-REQUISITESPRE-REQUISITES

• CONNECTIVITY (HW)

• SW

TYPES OF CMPTR NETWKS BASED ON

TRANSMISSION TECHNOLOGY

• BROADCAST NETWORKS

• PT-TO-PT NETWORKS

BROADCAST NETWORKS

• SINGLE COMN CH SHARED BY ALL CMPTRS ON

NW.

• PACKETS SEND BY ONE CMPTR RECEIVED BY

ALL OTHERS.

• ADDRESS FD IN PACKET- SPECIFIES FOR WHOM

INTENDED.

• PACKET CAN ALSO BE ADDRESSED TO ALL

CMPTRS (BROADCAST).

PT TO PT NETWORKS

• MANY CONNECTIONS BETWEEN INDL PAIRS OF

CMPTRS.

• PACKETS VISIT ONE OR MORE INTERMEDIATE

MACHINES.

• MULTIPLE ROUTES .

• SMALLER NETWORKS – BROADCAST

• LARGER NETWORKS – PT TO PT

TYPES OF COMPUTER NETWKS BASED ON

GEOGRAPHICAL SPREAD

• LAN

•MAN

•WAN

•INTERNET

LOCAL AREA NETWORKS• PRIVATELY OWNED.

• WITHIN SAME BLDG/ CAMPUS – UPTO A FEW KMs.

• SPEED 10/100/1000 Mbps.

• NORMALLY BROADCAST TYPE / SWITCHED - STATIC,

DYNAMIC

• TRANSMISSION TECHNOLOGY - SINGLE CABLE.

• TOPOLOGY (BUS , RING)

• SIMPLE NETWORK MGT

METROPOLITAN AREA NETWORKS

• BIGGER VERSION OF LAN.

• USES SIMILAR TECH AS LAN.

• MAY COVER A CITY.

• CAN BE PRIVATELY OWNED OR PUBLIC.

• NO SWITCHING ELEMENTS (SIMPLE DESIGN).

WIDE AREA NETWORKS

• SPANS LARGER GEOGRAPHICAL AREA.

• COLLECTION OF CMPTRS RUNNING APPLICATION

PROGRAMS (HOSTS).

• SUBNET - CARRY MSGS FROM HOST TO HOST.

• SWITCHING ELEMENTS (ROUTERS).

• PACKET SENT FROM ROUTER TO ROUTER. (STORE AND FWD

/ PT TO PT)

• PT TO PT TOPOLOGIES

INTER-NETWORKS

• CONNECTING DIFFERENT NETWORKS WITH

DIFFERING TOPOLOGIES / INCOMPATIBILITIES

• CONNECTED THROUGH GATEWAYS

WIRELESS NETWORKS

• LOW SPEEDS 1-2 Mbps

• HIGH ERROR RATES

• LIABLE TO INTERFERENCE

LAN TOPOLOGIES• TOPOLOGY THE GEOMETRIC ARRANGEMENT OF

DEVICES IN A NETWORK.

• TYPES OF TOPOLOGIES

• STAR TOPOLOGY

• RING TOPOLOGY

• BUS TOPOLOGY

• HYBRID TOPOLOGY

LAN – STAR TOPOLOGY

LAN – RING TOPOLOGY

LAN – BUS TOPOLOGY

LAN – HYBRID TOPOLOGY

DESIGNING: UNIT LEVEL LAN

DESIGN OF A LAN• NETWORK PLG – NO OF CLIENTS, FUTURE

GROWTH, NW COMPONENTS, NO OF SERVERS, TYPE OF CABLING.

• NETWORK DESIGN – LOC OF SERVERS, TOPOLOGY, PHYSICAL LAYOUT, SOFTWARE USAGE ETC.

BOTTOM LINE; MAKE A BLUE PRINT.

• IMPLEMENTATION AND FINE TUNING.

• PHYSICAL AUDIT – TYPE OF MACHINE, REGD NOS, HARDWARE USERS, OS INSTALLED WITH VER, CD OF OS & OTHER APPLICATIONS.

Contd…

• DESIGNATE SYS ADMINISTRATOR.

• KEEP RECORD OF –

•SERVER CONFIG

•NIC CONFIG

•TCP/IP ADDRESS

•USER NAMES & PASSWORDS

•EMAIL CLIENT CONFIG

•NW SERVICES (PRINTERS, FILE SHARING, PERMISSIONS ETC)

SUGGESTED LAYOUT OF UNIT LAN

SERVER

ADJT

QM

2IC

CODOCU CELL

PAY &ALLCES

CELL

D COY

A COY

B COY

C COY

G BR PRI Q BRA BR

CYBER SECURITYCYBER SECURITY

INFO SECURITYINFO SECURITY

GUIDING PRINCIPLEGUIDING PRINCIPLE

Cyber Security in Army is based on the guiding principle that the person who is generating info is also resp for its security.

• MOST SECURITY BREACHES OCCUR DUE TO : - POOR PASSWORD MGMT. NON ACCTG OF REMOVABLE MAGNETIC MEDIA. STORING OF CLASSIFIED INFO ON CMPTR HDD. POOR NETWORK ADMIN. UNACCTD COPYING OF DATA ON REMOVABLE MEDIA WEAK AUTHENTICATION PROCEDURES & ACCESS

CONTROL. VULNERABILITY OF OP SYS & COTS SOFTWARE. ABSENCE OF ADEQUATE TOOLS & STD FOR DATA

ENCRYPTION

CAUSES OF SECURITY CAUSES OF SECURITY BREACHESBREACHES

LIKELY BREACHESLIKELY BREACHES

PERSONAL SECURITYPHYSICAL SECURITY HARDWARE SECURITYSOFTWARE SECURITYDATABASE SECURITY

SECURITY WHILE USING SECURITY WHILE USING ARMY INTERNETARMY INTERNET

DIAL UP ACCESS NOT PERMITTED. ONLY UNCLAS INFO TO BE TRANSMITTED.

NEVER CONNECT THE NEVER CONNECT THE INTERNET PC TO YOUR INTERNET PC TO YOUR OFFICE LAN OR ARMY OFFICE LAN OR ARMY

INTRANETINTRANET

SECURITY MSR WHILE USING SECURITY MSR WHILE USING INTERNETINTERNET

ONLY STAND ALONE PC TO BE USED. HDD NOT TO HAVE OFFICIAL DATA. ACCESS TO INTERNET ONLY ON NEED BASIS. LATEST AV SOFTWARE, CHECK ALL

DOWNLOADS FOR VIRUSES. FIREWALL PROTECTED. IN CYBER LABS, PLACE PC BEHIND PROXY

SERVER & FIREWALL.

Contd/-

PERIPHERALS ON INTERNET NOT TO BE SHARED FOR OFFICIAL WK.

MAINT USAGE REGISTER IN INTERNET LAB. BIOS, USER, SCREEN SERVER PASSWORD. AVOID ENTICING SITES. PCS AT HOME BEING USED FOR INTERNET - NO

OFFICIAL DATA ON HDD. DO NOT SURF THE NET ON AN ADMIN ACCT.

VIRUS PROTECTIONVIRUS PROTECTION REGULAR CHECK OF HDD. USE ONLY LEGAL SOFTWARE. RUN AV SOFTWARE WHEN OPENING ANY

FILE.

REPAIR & MAINTREPAIR & MAINT AS FAR AS POSSIBLE, IN-SITU REPAIRS. STN WKSP RESP FOR REPAIRS AFTER WARRANTY.

REMOVE HDD BEFORE SENDING TO WKSP. REPAIR THROUGH CIV FIRM DURING WARRANTY.

IN SITU, PHYSICAL PRESENCE OF PERS DURING REPAIRS.

IF SYS TO BE MOVED OUT, REMOVE HDD. UNREPAIRABLE HDD, GET CERTIFIED AS BER.

PHYSICAL DESTRUCTION.