Introduction To Internetworking Devices - … · Introduction To Internetworking Devices . ... • Data Over Cable Service Interface Specification ... •

Information Security Education and Awareness

Centre for Development of Advanced Computing

Hyderabad

1

Introduction To Internetworking

Devices



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Introduction

• Internetworking

Devices are essential

to connect

– LAN to LAN

– LAN to WAN

– LAN to

internetworking

devices

– LAN to Interconnect

Segments



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Need of Internetworking

Devices

• To separate/connect one corporate division with

another.

• To connect two LANs with different protocols.

• To connect a LAN to the Internet.

• To split a LAN into segments to reduce traffic

congestion.

• To provide a security wall between two different types

of users.

• To connect WLAN to LAN



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Internetworking Devices

• Some of the internetworking devices are: – Cables

– Repeaters

– Hubs

– Bridges

– Switches

– Routers

– Gateways

– VPN’s

– DMZ’z

– Honey Pots

– Wireless Devices



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Transmission Medium and Physical

Layer



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Types of Transmission Media

Transmission Media

Guided Media Unguided Media

Twisted

Pair Cable

Coaxial

Cable

Fiber- Optic

Cable Radio Microwave Satellite



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Twisted-Pair Cable



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Guided Media Types

– Shielded twisted-pair (STP)

– Unshielded twisted-pair (UTP)

– Coaxial cable

– Fiber-optic cable



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Shielded twisted-pair

• Shield is added to the ordinary

twisted pair telephone wires:

– Functions as a ground

• Special kind of copper

telephone wiring – Used some business

installations

• Frequently installed with two

pairs

– Eg: Modem to connect

another line

• Comes with each pair uniquely

color-coded

• Least expensive cable



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Unshielded twisted-pair (UTP)

• Not shielded and thus

interfere with near

cables

• Used in LANs to bit rates

of 100Mbps and with

maximum length of 100m

• Used to connect a

computer to a network

• Two types – Coaxial cable:

– Fiber-optic cable:



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UTP Connector



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Coaxial cable

• Has a grounded metal cover around the signal conductor.

• Interference among cables is reduced due to the covering around signal conductor.

• Allows higher data rate transfer.

• Typically they are used at bit rates of 100 Mbps for maximum lengths of 1 km.



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Categories of Coaxial Cables

RG-59 75 ohms Cable TV

RG-58 50 ohms Thin Ethernet

RG-11 50 ohms Thick Ethernet

Category Impedance Use



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Fiber-optic cable

• Do not interfere with nearby cables.

• Give greater security.

• Allows extremely high bit rates over long distances.

• Provide more protection from electrical damage by external equipment and greater resistance to harsh environment.

• Safer in hazardous environment



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Propagation Modes of Fiber Optics

Multimode Single mode

Step index Graded Index

Mode



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Applications of Guided Media

• Used in telephone lines to provide voice

and data channels.

• Local area networks , such as 10 Base-T

and 100 Base-T

• Used in

– Cable TV networks

– Traditional Ethernet LANs

– TV companies.



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Unguided Media Types

• Radio

• Microwave

• Satellite



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Radio Waves

• Ranging in frequencies between 3KHz and

1GHz

• Omni directional.

• Propagate in the sky mode , can travel

long distances

– AM Radio



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Radio Transmission

Radio Tower Home

Earth

50 KM

Atmosphere



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Microwave

• Travel in straight line

• Electromagnetic waves having frequency

between 1 and 300 GHz are called as

Micro waves.

• Micro waves are unidirectional.

• Microwave propagation is line of sight.

• Cannot penetrate walls.

• Band is relatively wide, almost 299 GHz



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Microwave

Transmitter Repeater

Receiver



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Satellite Transmission

• Object that revolves around a planet in a circular path

• Man made and have been launched into orbit to carry out specific functions

• Typically between 100 and 24,000 miles away

• Purposes including data communications, scientific applications and weather analysis

• Do not have the limitations of ground based wireless transmission, such as the curvature of the Earth.



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Satellite Applications

• Weather

• Government

• Air Traffic Control

• Earth Observation



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Basic elements

24



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OSI reference

27



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Security Concerns

• Easily tapped physical transmission

medium

• If a customer enables file sharing on any

drives

– Neighbors could even download copies of

their data

• Lack of continuity of service



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Countermeasures

• Bundling security features in the cable modem hardware

• Data Over Cable Service Interface Specification (DOCSIS) – Authentication and packet filtering

• Consider laying the cable in transparent medium – Thereby allowing ready identification of any interference

• Prevent physical access to them

• Ensure that network access points are disabled if equipment is removed



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Reference

• http://homepages.uel.ac.uk/u0115449/myweb14/Inter

networking%20Devises.htm#Cables

• http://searchnetworking.techtarget.com/dictionary/de

finition/214235/shielded-twisted-pair.html

• http://www.psu.edu

• http://www.csi.ucd.ie/Staff/jmurphy/networks/csd8_

6-intntkdevs.pdf

• http://en.wikipedia.org/wiki/Computer_networking

• http://www.uni-

koblenz.de/~ros/Rechnerorganisation/internetworking.

pdf

http://homepages.uel.ac.uk/u0115449/myweb14/Internetworking Devises.htm


http://searchnetworking.techtarget.com/dictionary/definition/214235/shielded-twisted-pair.html






http://www.psu.edu/

http://www.csi.ucd.ie/Staff/jmurphy/networks/csd8_6-intntkdevs.pdf




http://en.wikipedia.org/wiki/Computer_networking

http://www.uni-koblenz.de/~ros/Rechnerorganisation/internetworking.pdf






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Reference

• http://www.comp.hkbu.edu.hk/~comp2650/lecture/no

tes/Chapter1.pdf

• http://en.wikipedia.org/wiki/Cable

• http://en.wikipedia.org/wiki/Twisted_pair#Unshielded

_twisted_pair_.28UTP.29

• http://fcit.usf.edu/network/chap4/chap4.htm#UTP

http://www.comp.hkbu.edu.hk/~comp2650/lecture/notes/Chapter1.pdf

http://www.comp.hkbu.edu.hk/~comp2650/lecture/notes/Chapter1.pdf

http://en.wikipedia.org/wiki/Cable

http://en.wikipedia.org/wiki/Twisted_pair

http://en.wikipedia.org/wiki/Twisted_pair

http://fcit.usf.edu/network/chap4/chap4.htm



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Repeaters



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Repeater

• Receives and simultaneous transmits

signal

• Preserve signal integrity

• Two way contact

• Generally Located at a high place

• Correct pair of frequencies



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Types of Repeaters

• FM Voice

• ATV – Amateur Television

• AM and SSB

• Digipeaters



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Use of repeaters

• Influence the quality of communication

on the network

• Greater Range

– Greatly enhances the ability to communicate

with distance stations

• Two way contact

– Ex: Illustrated in the next Slide



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Repeaters Amplifying Weak Signals

Repeater

Sending Workstation

500 Meters

Receiving Workstation



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Access Point as Repeater

Access Point

AP3

Access Point

AP1

Access Point

AP2



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Modes

• Simplex

– Vice-Versa of Duplex Mode

– Stations Operate in Half-Duplex Mode

• Duplex

– Transmit and receive signals simultaneously

– Example: Repeaters



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Security Issues

• Security concerns:

– Privacy

• End-to-end encryption (e.g., IPSec) can be used

– Greedy/malicious repeaters

• Client monitors channel quits if performance

becomes worse after SoftRepeater is used



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Advantages and Disadvantages

• Advantage – Transparency

• LANS can be connected without any knowledge from the hosts.

– Useful for serving multiple machines in an office from one Ethernet outlet.

• Disadvantage – Not scalable

• Ethernet standard allows only 4 repeaters.

• More than 4 would introduce delays that would break contention detection.

– No Heterogeneity

• Networks connected with repeaters must have identical electrical properties.



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Reference

• http://www.authorstream.com/Presentation/Edolf-35588-Chapter-02-CHAPTERTWO-Objectives-Repeaters-Hubs-Advantages-Disadvantages-Network-Segmentation-Bridges-Tr-as-Entertainment-ppt-powerpoint/

• http://homepages.uel.ac.uk/u0115449/myweb14/Internetworking%20Devises.htm#Cables

• http://searchnetworking.techtarget.com/dictionary/definition/214235/shielded-twisted-pair.html

• http://homepages.uel.ac.uk/u0115449/myweb14/Internetworking%20Devises.htm#Cables

• http://www.psu.edu

http://www.authorstream.com/Presentation/Edolf-35588-Chapter-02-CHAPTERTWO-Objectives-Repeaters-Hubs-Advantages-Disadvantages-Network-Segmentation-Bridges-Tr-as-Entertainment-ppt-powerpoint/













































http://www.psu.edu/



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Hub



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Hubs

• Layer 1 devices in the OSI model.

• Hubs do not read any of the data passing

through them

• Not aware of their source or destination.

• Essentially, a hub simply receives

incoming packets



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Hubs( Contd)

• Interconnects two or more workstations

• Resends the data frame out all

connecting links.

• Managed or unmanaged.



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Hubs (Contd..)

• Used to tie several networking cables

together

• Creates a link between different stations

on a network

• Generally connected in star topology

– Ex: Illustrated in next slide



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Hubs Star Topology

Hub

Computer

Computer

Computer

Computer

Computer



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Types

• Active Hubs

– Plugged into electric power

• Passive Hub

– Merely connects to different network cable

– No signal regeneration

• Intelligent

– Typically is stackable

– Includes remote management capabilities via SNMP and virtual LAN (VLAN) support.



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Advantages

– Cheap

– Shared Internet Access

– Scalability

– Network Monitoring

– Backward Compatibility



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Disadvantages

– Broadcast all the information to every

node connected

– Slow speed of over network

– More prone to collisions and less

reliable

– Create loops



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Security Concerns

• Total computers on the network gets

infected

– Remove it from the network

– Necessary Policies

– Use Network based IDS



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Reference

• http://compnetworking.about.com/od/hardwarenetworkgear/l/aa012801a.htm

• http://ist.psu.edu/faculty_pages/giles/IST220/vghs/Ch8.ppt

• http://ist.psu.edu/faculty_pages/giles/IST220/vghs/Ch8.ppt

• http://www.storrconsulting.com

• http://www.exforsys.com/tutorials/networking/star-topology.html

• http://fcit.usf.edu/Network/chap5/chap5.htm

http://compnetworking.about.com/od/hardwarenetworkgear/l/aa012801a.htm


http://ist.psu.edu/faculty_pages/giles/IST220/vghs/Ch8.ppt




http://www.storrconsulting.com/

http://www.exforsys.com/tutorials/networking/star-topology.html




http://fcit.usf.edu/Network/chap5/chap5.htm



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Reference( Contd)

• http://compnetworking.about.com/od/hardwa

renetworkgear/l/aa012801a.htm

• http://answers.yahoo.com/question/index?qid

=20071122033700AA4h9YN

• http://www.ehow.com/facts_4795873_advanta

ges-disadvantages-ethernet-hubs-switches.html

• http://www.it.northwestern.edu/policies/conc

erns.html



http://answers.yahoo.com/question/index?qid=20071122033700AA4h9YN

http://answers.yahoo.com/question/index?qid=20071122033700AA4h9YN

http://www.ehow.com/facts_4795873_advantages-disadvantages-ethernet-hubs-switches.html










http://www.it.northwestern.edu/policies/concerns.html

http://www.it.northwestern.edu/policies/concerns.html



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Bridges



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Bridges

• Operate at the Data Link layer of the OSI

model

• Connect two similar LANs,

– CSMA/CD LAN and a

– Token ring LAN.

• Protocol-independent

• Examines the destination MAC address



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Undetected Collision

A B C

A and B might transmit short frames at the same time. They could be done

transmitting before they received the other’s frame. The transmitters do not

detect a collision, but nodes in the middle cannot receive the frame.



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A B

A has started to transmit a frame. The first bit of the frame has almost

reached node B.



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A B

B starts to transmit a frame and immediately notices a collision. A

does not know of the collision yet.



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A B

A must still be transmitting when the first bits of B’s aborted

transmission reaches it.



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A bridge interconnecting two

dissimilar LANs

Hub

CSMA/CD LAN

Bridge

CSMA/CD Frame

Token Ring Frame

Token Ring LAN



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Bridge interconnecting two identical

LANs

LAN 1 LAN 2

Server

workstation Printer

Server

workstations

CSMA/CD CSMA/CD



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Types

• Transparent Bridges

• Source-Routing Bridges and

• Translation Bridges



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Transparent Bridges

• Observes all traffic and builds routing tables

• Two connections – Ports

– Routing table

• Found with CSMA/CD LANs – Ethernet Network

• Also called as learning bridges

• Convert one frame format to another

• Bridges that execute the spanning tree algorithm are called transparent bridges



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Transparent Bridges

Bridges

Segment A

Segment B

Computer 1

Computer 2 Computer 3

Computer 4 Computer 5 Computer 6



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What is Learning Bridge

• A host can be moved to another network.

• New hosts can be added at any time.

• Requires no setup information from

humans.

• One major flaw:

• Ex: Illustrated in the next slide



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Problem for the transparent Bridges

Bridge A Bridge B

Host A

Host B

Network 1

Network 2



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Possible Solutions

• Tell customers to avoid topologies that

include loops

• Design bridges that shorten the network

topology into something with no loops

• Spanning-Tree Algorithm

– Preserve the benefits of loops



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Types of Transparent Bridge

Modes

• Store-and-Forward

– Stores the entire frame and verifies the CRC before forwarding the frame.

– If a CRC error is detected, the frame is discarded.

• Cut-Through

– Forwards the frame just after it reads the destination MAC address without performing a CRC check.



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Source-routing Bridges

• Do not learn from watching tables

• Rely on the source of the frame transmission

– If not workstation sends discovery frame

• Employed by Token Ring networks

• IEEE 802.5 standard

• Consists of Routing information indicator

– When this is set to '1' the frame needs to be route

according to the Route Information Field.

– If the RII is '0' the frame stays on the same LAN.



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Route Discovery Frame

• Technique used to find the best path between stations

– By the Transmission of broadcast discovery frames(BDF) between the source and destination stations

• Two types

– Single Route Broadcast (SRB)

– All Routes Broadcast (ARB)

• Specifically Routed Frame (SRF)



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Translation or Remote Bridges

• Connect networks with different

architectures

• Takes the frame before it leaves the first

LAN

– Encapsulates the WAN headers and trailers.

• Differentiate LAN and WAN speeds



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Advantages and Disadvantages

• Advantages

– Extend a network by acting as a repeater

Bridges can reduce network traffic

– Increase the available bandwidth

– No network collision

– Connect networks using different media

types and architectures



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Disadvantage

• Disadvantage

– Slower than repeaters

• Bcoz more by viewing the MAC address

– More processing time

– Do not filter broadcast traffic

– More expensive than repeaters



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Reference

• http://faculty.unlv.edu/jchang/Chapter7.ppt

• http://cswilliams.ncat.edu/Networks/Interconnecting.

pdf

• http://home.iitk.ac.in/~navi/sidbinetworkcourse/lectu

re6.ppt


pdf

• http://nptel.iitm.ac.in/courses/Webcourse-

contents/IIT%20Kharagpur/Computer%20networks/pdf/

M6L1.pdf

http://faculty.unlv.edu/jchang/Chapter7.ppt

http://cswilliams.ncat.edu/Networks/Interconnecting.pdf


http://home.iitk.ac.in/~navi/sidbinetworkcourse/lecture6.ppt

http://home.iitk.ac.in/~navi/sidbinetworkcourse/lecture6.ppt



http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT Kharagpur/Computer networks/pdf/M6L1.pdf






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Reference


pdf

• http://www.freepatentsonline.com/4573045.html


pdf

• http://www.hill2dot0.com/wiki/index.php?title=CSMA/

CD


• http://nptel.iitm.ac.in/courses/Webcourse-

contents/IIT%20Kharagpur/Computer%20networks/pdf/

M6L1.pdf



http://www.freepatentsonline.com/4573045.html



http://www.hill2dot0.com/wiki/index.php?title=CSMA/CD

http://www.hill2dot0.com/wiki/index.php?title=CSMA/CD








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Reference



• http://www.comm.utoronto.ca/~jorg/teaching/ece461

/slides/module16-lanswitchingV3.ppt

• http://www.comm.utoronto.ca/~jorg/teaching/ece461

/slides/module16-lanswitchingV3.ppt

• http://www.cisco.com/en/US/docs/internetworking/t

echnology/handbook/Transparent-Bridging.pdf

• http://www.cisco.com/en/US/docs/internetworking/t

echnology/handbook/Transparent-Bridging.pdf



http://www.comm.utoronto.ca/~jorg/teaching/ece461/slides/module16-lanswitchingV3.ppt








http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Transparent-Bridging.pdf










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Reference

• http://www.webopedia.com/TERM/T/transparent_bridge.html

• http://publiespe.espe.edu.ec/articulos/sistemas/switch/switch.htm

• http://ckp.made-it.com/bridges.html#SRB

• http://www.rhyshaden.com/tokenr.htm#Source

• http://ckp.made-it.com/bridges.html#SRB

• http://www.linktionary.com/s/source_routing.html

• http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Source-Route-Bridging.pdf

• http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Bridging-Basics.html

http://www.webopedia.com/TERM/T/transparent_bridge.html

http://www.webopedia.com/TERM/T/transparent_bridge.html

http://publiespe.espe.edu.ec/articulos/sistemas/switch/switch.htm

http://publiespe.espe.edu.ec/articulos/sistemas/switch/switch.htm

http://ckp.made-it.com/bridges.html



http://www.rhyshaden.com/tokenr.htm




http://www.linktionary.com/s/source_routing.html

http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Source-Route-Bridging.pdf






http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Bridging-Basics.html






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Reference

• http://www.authorstream.com/Presentation/Edolf-35588-Chapter-02-CHAPTERTWO-Objectives-Repeaters-Hubs-Advantages-Disadvantages-Network-Segmentation-Bridges-Tr-as-Entertainment-ppt-powerpoint

• http://en.wikipedia.org/wiki/Bridging_%28networking%29#Advantages_of_network_bridges

http://www.authorstream.com/Presentation/Edolf-35588-Chapter-02-CHAPTERTWO-Objectives-Repeaters-Hubs-Advantages-Disadvantages-Network-Segmentation-Bridges-Tr-as-Entertainment-ppt-powerpoint



































http://en.wikipedia.org/wiki/Bridging_%28networking%29

http://en.wikipedia.org/wiki/Bridging_%28networking%29



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Switch



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Switch

• Increase network performance

– By reducing the number of packets

transmitted to the rest of the network Like

bridges

• Operate at the Data Link layer of the OSI

model

• In an Ethernet network, computers are

usually connected directly to a switch



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Switches

• It is An Intelligent device works at Data link layer device

• It works with Physical addresses (i.e. MAC addresses) and Maintains a MAC Address table.

• It works with Flooding and Unicast

• It has 1 Broadcast domain and Number of Collision domains depends upon the number of ports.



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Types of Switches

• Manageable switches

– IP address can be assigned and configurations

can be made.

– It has a console port .

• Unmanageable switches

– Configurations cannot be made, an IP address

cannot be assigned

– No console port



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Advantages of Switches

• Increase available network bandwidth

– Reduced workload on individual computers

• Increase network performance

– Fewer frame collisions

• Unlimited number of ports and connect

directly to workstations



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Disadvantage

• More expensive than bridges

• Network connectivity problems can be

difficult to trace

• Switch Broadcast traffic may be

troublesome



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Reference

• http://www.authorstream.com/Presentation/Edolf-

35588-Chapter-02-CHAPTERTWO-Objectives-Repeaters-

Hubs-Advantages-Disadvantages-Network-

Segmentation-Bridges-Tr-as-Entertainment-ppt-

powerpoint









































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Routers



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Routers

• Layer 3 device

• Logical addressing (IP Address)‏

• Connecting different network segments

• Best path selection

• Shares details with other routers

• Works in LAN, WAN environments

• Create collision domain

• Not pass broadcast traffic



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What is Router

• A device in the network that processes and routes data between two points

• A device that routes data between networks using IP addressing

• A layer 3 device

• Hardware or software used to connect two or more networks

Internet



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Advantages of Routers

• Connect different network architectures

• Uses dynamic routing techniques

– For best path or route

• Reduces network traffic

– Do not retransmit network broadcast traffic



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Disadvantage

• Work only with routable network

protocols

• More expensive than bridges or repeaters

• Dynamic router communication causes

additional network overhead

• Slower than bridges or switches

– Analyze a data transmission from the

Physical through the Network layer



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Reference

• http://www.networkmagazineindia.com/200105/basics

1.htm

• http://ckp.made-it.com/routers.html

http://www.networkmagazineindia.com/200105/basics1.htm

http://www.networkmagazineindia.com/200105/basics1.htm

http://ckp.made-it.com/routers.html





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Gateway Devices



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Introduction

• Aim is to:

– Share an Internet connection over a LAN

– Protect the LAN from the Internet

• Also hope to:

– Require only minimal maintenance

– Provide a remote administration capability

– Provide automatic configuration for LAN

– Not interfere with Internet operation



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Gateways

• Combination of hardware and software

• Translate between different protocols on

a network Latency Delay

• Internetworking system capable of joining

together two networks

• Operate at any level of the OSI model



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Why gateway

• To run services, such as:

– a domain name service for local machines,

– a shared web proxy,

– a personal or business web server,

– a mail server to centralize access to your mail,

– a file server for backup or extra storage

– Web filtering

– URL filtering

– Firewall



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Gateway web filtering

• Program that can screen an incoming Web page – To determine whether some or all of it should not be

displayed to the user

• The filter checks the origin or content of a Web page against a set of rules – Provided by company or person who has installed the

Web filter

• Block out pages from Web sites that are likely to include – objectionable advertising, pornographic content,

spyware, viruses, and other objectionable content.



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Contd..

• Secure networks from Web-based threats

• Provide reporting so that the installer can

see what kind of traffic is being filtered

and who has requested it

• Often installed as part of a proxy server

and firewall



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Firewall

• Firewalls define rules for

inbound/outbound network traffic

• Integration provides centralized policy

management

• Isolates organization’s internal net from

larger Internet,

– Allowing some packets to pass, blocking

others



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Firewalls: Why

• Prevent denial of service attacks: – SYN flooding: attacker establishes many bogus TCP

connections, no resources left for “real” connections.

• Prevent illegal modification/access of internal data. – e.g., attacker replaces CIA’s homepage with

something else

• Allow only authorized access to inside network

• Preventing visits to bad outside resources from internal network.



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Firewalls Types

• Software or a hardware offers various

services

– Packet filtering

– Proxy service

– Port filtering

• Two types

– Hardware

– Software



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Hardware Firewall

• Examples includes: – PIX

– ASA

• Services offered by hardware firewall – URL filtering

– Packet filtering

– NATTING

– IPSec

– Proxy service

– VPN

• Cost high



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Software Firewall

• Placed both inside and outside network

• Cost is low as compared hardware firewall

• Placing a software firewall inside the network optional but it’s mandatory to have firewall outside the network

• Offer all the services but few exceptions

• Not protect a network from: – Malwares

• Viruses

• Worms

• Trojan

– Internal threats

• Caused by disgruntled employees



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URL Filtering

• Block access to non-desirable web sites to

reduce

– Security, legal and regulatory risks.

• Reduce malware incidents by prohibiting

access:

– Malware and phishing download sites.

• Adapt web filtering control efforts

– Allow list, deny list and database customization.

• Facilitate SSL decryption policies



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Content Filtering

• Technique whereby content is blocked

– Based on analysis of its content

– Rather than its source or other criteria

• Widely used on the internet to filter

– email and

– Web access



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Content filtering of email

• Methods to filter spam

• Act either

– on the content, information contained in the mail

body like subject etc » And classify, accept or reject a message

• Popular filter is the Bayesian filter

• Anti-virus methods can be classified as content

filters too

– Scan simplified versions of either the binary

attachments of mail



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Content filtering methods

• Attachment - The blocking of certain types of file (e.g. executable programs).

• Bayesian – a method to detect spam

• Char-set – Examples of characters include letters, numerical digits, and

common punctuation marks

• Content-encoding

• Heuristic - Filtering based on heuristic scoring of the content based on multiple criteria.

• HTML anomalies

• Language



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Contd..

• Mail header

• Mailing List

• Phrases

• Proximity

• Regular Expression



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Reference

• http://www.networktutorials.info/gateway.html

• http://compnetworking.about.com/od/networkdesign/g/network-gateway.htm

• http://en.wikipedia.org/wiki/Microsoft_DNS

• http://wapedia.mobi/en/Proxy_server

• http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci863125,00.html

• http://www.untangle.com/web-filter

• http://www.paloaltonetworks.com/literature/datasheets/URL_Filtering_ds.pdf

• http://en.wikipedia.org/wiki/Content_filtering

http://www.networktutorials.info/gateway.html

http://compnetworking.about.com/od/networkdesign/g/network-gateway.htm




http://en.wikipedia.org/wiki/Microsoft_DNS

http://wapedia.mobi/en/Proxy_server

http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci863125,00.html


http://www.untangle.com/web-filter



http://www.paloaltonetworks.com/literature/datasheets/URL_Filtering_ds.pdf

http://www.paloaltonetworks.com/literature/datasheets/URL_Filtering_ds.pdf

http://en.wikipedia.org/wiki/Content_filtering



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Reference

• http://personal-firewall-software-

review.toptenreviews.com

• http://www.webopedia.com

• http://www.cisco.com

• http://searchsecurity.techtarget.com/sDefinition/0,,si

d14_gci1093128,00.html

• http://products.datamation.com/

• http://articles.techrepublic.com.com

• http://www.microsoft.com

http://personal-firewall-software-review.toptenreviews.com/







http://www.webopedia.com/

http://www.cisco.com/



http://products.datamation.com/

http://articles.techrepublic.com.com/

http://www.microsoft.com/



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Reference

• http://www.itmatrix.com/Solutions/WhyFirewall.aspx

• http://searchsecurity.techtarget.com/sDefinition/0,,si

d14_gci212125,00.html

http://www.itmatrix.com/Solutions/WhyFirewall.aspx





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VPN Devices



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VPN Devices

• VPN devices provide end-to-end secure and authenticated traffic

• Occurs across shared infrastructure:

– local area network (LAN), WAN connections, or the Internet

• Categorized into three basic configuration types:

– host-to-host, host-to-gateway, and gateway-to-gateway.



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Basic VPN Methodology

• Application – Pretty Good Privacy (PGP)

– Secure Shell (SSH)

• Transport – Secure Sockets Layer (SSL)

• Network – IPSec not only encrypt the payload of the packet,

but they also encrypt the TCP/IP information

• Data link – Point-to-Point Protocol (PPP), which allows the

encryption of packets



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VPN Security

• IPSec

• PPTP

• L2TP



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VPN Solution Components

Internet ISP

DNS

Server

Email

Server

Web

Server

www.cdac.in VPN Server

Demilitarized

Zone

Mobile

Worker

Administrator

Mobile

Worker



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Advantages and Disadvantages of

VPNs

• Remote network access

• Many levels of security to a shared

network medium,

– Including improved confidentiality, integrity,

and authentication

• Offer a secure and more cost-effective

solution



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Disadvantages of VPN

• Use of encryption brings about an

additional processing burden

• Most likely additional equipment that

must be purchased

• Fitting a VPN into an existing location can

also be a challenge in some environments

– Due to the additional packet overhead



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Reference

• http://compnetworking.about.com/od/vpn/a/vpn_tuto

rial.htm

• Inside Network Perimeter Security – By Stephen Northcutt, Lenny Zeltser, Scott Winters, Karen Kent,

Ronald W. Ritchey

http://compnetworking.about.com/od/vpn/a/vpn_tutorial.htm

http://compnetworking.about.com/od/vpn/a/vpn_tutorial.htm



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DMZ



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DMZ

• Short for Demilitarized Zone

• DMZ is a field where set all the private

service to public.

• For security concern, firewall products

provide LAN Interface and DMZ Internet

for Intranet.

• The field of DMZ is for public user can

share resource with Intranet.



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DMZ

Internet

Internal network

Firewall

Email

Server

Web

Server webmail.cdac.i

n

DMZ



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Honeypots



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Honeypots



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Introduction

• It is a highly flexible computer system on

the Internet

• It is expressly set up to attract and trap

people who attempts to penetrate other

people computer

• They are used for misdirection,

prevention, detection and information

gathering



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Honeypot

• Trap set to detect, deflect, or counteract attempts at unauthorized use of information systems

• Consists of a computer, data, or a network site that appears to be part of a network, but is actually remote, unprotected, and monitored – And which seems to contain information or a resource of value

to attackers.

• Valuable surveillance and early-warning tool

• Not see any legitimate traffic – No production

• Whatever they capture can then be surmised as malicious or unauthorized



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Honeypot (Contd)

• Can carry risks to a network, and must be

handled with care

• Victim hosts are an active network

counter-intrusion tool



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Purpose

• Distract attackers from the valuable

resources of network

• Provide early warning about new attacks

and intrusion attempts

• Used to know the attackers techniques

and methods



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Types

• Production Honeypots

• Research Honeypots



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Production Honeypots

– Easy to use, capture only limited information, and

are used primarily by companies

– Placed inside the production network with other

production servers by organization to improve their

overall state of security

– Easier to deploy

– Give less information about the attacks or attackers

than research honeypots

– Purpose of a production honeypot is to help mitigate

risk in an organization



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Research Honeypots

• Run by a volunteer, non-profit research organization or an educational institution – To gather information about the motives and tactics of the

Blackhat community targeting different networks

• Do not add direct value to a specific organization – Research the threats organizations face, and

– to learn how to better protect against those threats

• Complex to deploy and maintain

• Capture extensive information, and are used primarily by – research, military, or government organizations.



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Reference

• http://en.wikipedia.org/wiki/Honeypot_%28computing

%29

• http://www.honeypots.net/

• http://www.tracking-

hackers.com/papers/honeypots.html

• http://www.infinitel00p.com/library/honeypot.pdf

http://en.wikipedia.org/wiki/Honeypot_%28computing%29

http://en.wikipedia.org/wiki/Honeypot_%28computing%29

http://www.honeypots.net/

http://www.tracking-hackers.com/papers/honeypots.html



http://www.infinitel00p.com/library/honeypot.pdf



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Wireless Devices



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Wireless Devices



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What is Wireless?

• Physically

– Communication without wires

• Technically

– Transmission of signals through Electro

magnetic waves.



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Why Deploy Wireless?

• Unlicensed bands.

• Cost savings over wire line.

• Cannot run wire to locations needed.

• To enable customers to bring their own

laptop, therefore

– reducing the cost of owning many PCs



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Other Applications

• Bluetooth

– Short range(upto 10 mtrs),

– Low bandwidth communication.

– Works in 2.4 GHz band.

– Data rate up to 1 Mbps.



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Modes of Operation

• Ad-hoc

• Infrastructure



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Infrastructure Mode

• Requires a Basic Service Set (BSS), or a

Wireless Access Point

• Access point has to allow wireless

computers to the wired network

• Most corporate uses WLAN this mode as

they require access to wired network

• Services like Printers and File servers



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Ad-hoc Mode

• Peer-to-Peer Wireless Networking

• Have multiple wireless clients connecting

to each other

• Also known as Independent Basic Service

Set (IBSS)

• Can communicate with other wireless

computers



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Reference

• http://escarpment.net/

• Wireless Information Devices and the Mobile Internet Charles Davies Psion CTO

• http://www.authorstream.com/

• http://www.spamlaws.com/wc-networking.html

• http://compnetworking.about.com/cs/wirelessfaqs/f/adhocwireless.htm

• http://www.webopedia.com/TERM/A/ad_hoc_mode.html

• http://compnetworking.about.com/cs/wireless/f/infrawireless.htm

http://escarpment.net/

http://www.authorstream.com/

http://www.spamlaws.com/wc-networking.html



http://compnetworking.about.com/cs/wirelessfaqs/f/adhocwireless.htm

http://compnetworking.about.com/cs/wirelessfaqs/f/adhocwireless.htm

http://www.webopedia.com/TERM/A/ad_hoc_mode.html

http://www.webopedia.com/TERM/A/ad_hoc_mode.html

http://compnetworking.about.com/cs/wireless/f/infrawireless.htm

http://compnetworking.about.com/cs/wireless/f/infrawireless.htm

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