Module 01 - Introduction to Network Security
Content
Network Security Administrator
Module I: Introduction to Network Security
Module Objectives
~ ~ ~ ~ ~
Introduction to Network Topologies Types of Networks OSI Model Networking Devices Transmission Modes
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Module Flow
Network Topology
Types of network
Networking Devices
OSI Model
Transmission Modes
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Network Topology: Star
~ ~
All devices are connected to a controller located centrally called hub as a point-to-point connection The devices communicate with each other through the central hub
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Network Topology: Bus
A multi-point design consisting of a long cable called bus that connects all devices ~ All devices are connected to the bus using connections like drop lines and tabs
~
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Network Topology: Ring
All devices have a point-to-point connection with devices located on both sides ~ Communication between the devices is unidirectional
~
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Network Topology: Mesh
Every device has a point-to-point connection with every other devices ~ Unidirectional communication exists between any two devices
~
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Network Topology: Tree
~ ~
Majority of devices are connected to a controller located centrally called hub Other devices are connected to a derivative of the hub called a secondary hub
hub
hub
hub
hub
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Network Type: LAN
~
Features
• Extends over a small area within a kilometer
– Connects workstations and PCs of private property
~
Design
• Shares information between PC’s or workstations Ethernet Token Ring FDDI (Fiber Distributed Data Interface)
~
Technologies of LAN
• • •
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Network Type: LAN
Single Building LAN
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Network Type: WAN
~
Features • WAN facilitates communication over vast physical areas using public, leased or private devices – Length of a WAN can extend over some miles
~
Technologies of WAN • Packet Switched WANs • ATM • B-ISDN (Broadband ISDN)
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Network Type: WAN
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Network Type: MAN
Features • MAN provides communication for physical areas such as an entire city – Wireless infrastructure is used in a MAN communication • MAN can be owned by a private organization or a facility of a public organization ~ Technologies of MAN • Ethernet based MANs (Metro Ethernet) • DQDB (Distributed Queue Dual Bus) • SMDS (Switched Multi-megabit Data Services)
~
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Network Type: MAN
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OSI Model
Host A Host B
Application Layer Presentation Layer Session Layer
Messages Application Layer Messages Presentation Layer Messages Session Layer Segments Transport Layer Packets/Data gram Network Layer Frames/Cells Data Link Layer Frames/Cells Physical Layer
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Transport Layer Network Layer Data Link Layer Physical Layer EC-Council
Physical Layer
First layer of the OSI model ~ Responsibilities
~
• Communicating data streams over physical medium • Mechanical and electrical requirements of transmission media • Organization of bits of data • Data encoding
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Physical Layer
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Data Link Layer
Second layer of the OSI model ~ Responsibilities
~
• • • • •
Physical layer security Segregation of data into frames Transmission control Fault control Access control
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Data Link Layer
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Network Layer
Third layer of the OSI model ~ Responsibilities
~
• • • • •
Source to destination delivery of data packets The global addressing of the data packets Routing data packets to final destination Network traffic control Fault handling
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Network Layer
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Transport Layer
Fourth layer of the OSI model ~ Responsibilities
~
• • • • •
Addressing using service points Segregation and Re-gathering Link control Transmission control Fault handling
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Transport Layer
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Session Layer
Fifth layer of the OSI model ~ Responsibilities
~
• Establishing communication between processes • Organization of data using check points
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Session Layer
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Presentation Layer
Sixth layer of the OSI model ~ Responsibilities
~
• Deals with syntax and semantics of data exchange • Encryption of data for security • Data compression to reduce rate of data transmission
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Presentation Layer
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Application Layer
Seventh layer of OSI model ~ Responsibilities
~
• • • •
Permits users access to the network Provides mail services Provides directory services Provides network virtual terminal services for communicating with remote hosts
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Application Layer
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Network Device: Repeater
Electronic device that extends physical length of network • Function: Restores the signals before they become weak • Operates in OSI model at: – Physical layer ~ Advantages • Links segments of network of different medium ~ Disadvantages • Improper monitoring compromises entire network • Enhances traffic on the segments • No traffic segregation
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Network Device: Repeater
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Network Device: Multiplexer
~ ~
Device that merges multiple electric signals into a single signal Function • Combines several inputs into a single output • Combines digital and analog signals
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Network Device: Multiplexer
~
Advantages
• Multiplexer allows several digital signals to be transmitted using a single physical channel
~
Disadvantages
• Denial-of-Service weakness is present in some Multiplexer • Two streams of data competing for a single channel cause delay in transmission
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Network Device: Routers
~ ~
Hardware device that determines the best path for data transmission Function
• Sends packets across several interconnected networks
~
Operates in OSI model at
• Physical layer • Data link layer • Network layer
~
Types
• • • • Backbone routers Broadband Routers IP Routers Remote Access Routers
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Network Device: Routers
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Network Device: Routers
~ Advantages
• Routers can link diverse media such as LAN, WAN and can transmit data • Routers avoid data collisions during transmission
~
Disadvantages
• The sent packets cannot be sort out causing additional transmission that increases cost • Routers do not have restricted access controls
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Network Device: Brouter
Device that works as router and bridge ~ Operates like a bridge and forwards the data to the next segment ~ Functions
~
• Routes TCP/IP packets • Bridges data it cannot route
~
Advantages
• Uses physical address • Used for mixed-protocol traffic
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Network Device: Hub
~
Device to connect devices in a network
• Function: Groups devices into a single network segment • Performance: Provides optimized and preset remote IP services to medium sized networks
~
Types
• Passive Hub • Active Hub
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Network Device: Hub
~
Advantages
• Computers and broadband modems connect to the network through the Hub • Prevents network crashes • Allows mixing of slow (10 Mb/sec) and fast (100 Mb/sec) Ethernet devices
~
Disadvantage
• Computers that are connected to isolated hubs, are isolated from the network
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Network Device: Switch
Device which directs incoming data to a single output port from number of input ports ~ Function
~
• Directs data flow through specific path • Forwards data using MAC address embedded in each data packet
~
Advantages and Disadvantages
• Works efficiently than Hub • Packet sniffing is possible
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Network Device: Bridge
~ ~ ~
Logical devices that segments LANs to decrease the traffic flow in the network Function
• Segregates traffic by dividing the network into segments
Operates in OSI Model at
• Physical layer • Data link layer
B r id g e
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Network Device: Bridge
~
Advantages
• Used as filters • Segregation of networks into segments makes it trustworthy • Adaptable to higher protocols at MAC layer
~
Disadvantages
• Congestion due to high network traffics • Delays in transmission due to buffering of frames
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Network Device: Modem
~ ~
Device that acts as both modulator and demodulator Function:
• Provides serial communication capabilities across phone lines
~
Speed of modem depends on the speed of Universal Asynchronous Receiver/Transmitter (UART) chip in the Computer Disadvantage:
• Transmission of data is slow
~
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Network Device: Cables
~
Wires that connect network devices with each other across the network Function • Transfers raw data between network devices
~
~
Types of cable • Twisted pair • Coaxial • Optical fiber
~
Advantages and Disadvantages • Less problems with networking during bad weather • To take backup, there is a necessity of extra cables makes it expensive
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Network Device: ISDN Terminal Adapter
~ ~
Interfacing device Function
• Translates the signal between two digital adapters
~
Advantages
• Allows non-ISDN terminal at physical layer to communicate with ISDN network • Available as add-in expansion cards which are installed into computers
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Network Device: Network Card
~ ~
Device that joins computers in LANs Function
• Enables systems to connect to the network • Provides connectivity between nodes
~
Advantages
• Used in server clusters • NICs need not be fixed with physical cable • Used to both send and receive data
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Data Transmission Modes
~ Half -Duplex: ~ Full-
Duplex:
• Data is transmitted in LANs only one direction at a time • Broadband network supports half-duplex communication
• Data is transmitted in LANs simultaneously in both directions • Using suitable equipment full duplex communication can be obtained in some LAN’s and Ethernet
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Broadband and Baseband
~
Broadband
• Used in LAN’s • Transmits single signal through single cable simultaneously • Data transmitted is divided into distinct units called frames
~
Baseband
• Used in WANs • Transmits multiple signals through a single cable simultaneously
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Segments and Backbone
Segments
• LAN’s comprising of networked terminals and user equipment • Used for large organization networks
~
~
Backbones
• Collection of LAN’s that are are interconnected to another LAN called Backbone • Acts like a channel facilitating communication between segments
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Client/Server and Peer-to-Peer Networking
~ Client/Server
Network
• In a network, some computers function as clients and some as servers
• Client:
– A computer that gains from the services provided by server
~ Peer-to-Peer
Network
• Server:
– A computer that offers services to a client
• Individual computers function as both clients and servers • Confined to small groups of computers and networks smaller than single LANs
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Summary
~ ~ ~ ~ ~ ~
Network Topology is the arrangement of network devices Different types of topologies are Star Topology,Bus Topology,Ring Topology,Mesh Topology,Tree Topology The different types of networks are LAN,MAN,WAN OSI model covers all the features of network communications Networking devices are used for sharing the data or resources in a network Transmission mode is the path of the signal flow between two connected devices.It can of types HalfDuplex and Full- Duplex
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Module I: Introduction to Network Security
Module Objectives
~ ~ ~ ~ ~
Introduction to Network Topologies Types of Networks OSI Model Networking Devices Transmission Modes
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Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Module Flow
Network Topology
Types of network
Networking Devices
OSI Model
Transmission Modes
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Network Topology: Star
~ ~
All devices are connected to a controller located centrally called hub as a point-to-point connection The devices communicate with each other through the central hub
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Topology: Bus
A multi-point design consisting of a long cable called bus that connects all devices ~ All devices are connected to the bus using connections like drop lines and tabs
~
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Topology: Ring
All devices have a point-to-point connection with devices located on both sides ~ Communication between the devices is unidirectional
~
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Network Topology: Mesh
Every device has a point-to-point connection with every other devices ~ Unidirectional communication exists between any two devices
~
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Network Topology: Tree
~ ~
Majority of devices are connected to a controller located centrally called hub Other devices are connected to a derivative of the hub called a secondary hub
hub
hub
hub
hub
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Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Type: LAN
~
Features
• Extends over a small area within a kilometer
– Connects workstations and PCs of private property
~
Design
• Shares information between PC’s or workstations Ethernet Token Ring FDDI (Fiber Distributed Data Interface)
~
Technologies of LAN
• • •
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Network Type: LAN
Single Building LAN
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Network Type: WAN
~
Features • WAN facilitates communication over vast physical areas using public, leased or private devices – Length of a WAN can extend over some miles
~
Technologies of WAN • Packet Switched WANs • ATM • B-ISDN (Broadband ISDN)
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Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Type: WAN
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Network Type: MAN
Features • MAN provides communication for physical areas such as an entire city – Wireless infrastructure is used in a MAN communication • MAN can be owned by a private organization or a facility of a public organization ~ Technologies of MAN • Ethernet based MANs (Metro Ethernet) • DQDB (Distributed Queue Dual Bus) • SMDS (Switched Multi-megabit Data Services)
~
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Network Type: MAN
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OSI Model
Host A Host B
Application Layer Presentation Layer Session Layer
Messages Application Layer Messages Presentation Layer Messages Session Layer Segments Transport Layer Packets/Data gram Network Layer Frames/Cells Data Link Layer Frames/Cells Physical Layer
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Transport Layer Network Layer Data Link Layer Physical Layer EC-Council
Physical Layer
First layer of the OSI model ~ Responsibilities
~
• Communicating data streams over physical medium • Mechanical and electrical requirements of transmission media • Organization of bits of data • Data encoding
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Physical Layer
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Data Link Layer
Second layer of the OSI model ~ Responsibilities
~
• • • • •
Physical layer security Segregation of data into frames Transmission control Fault control Access control
EC-Council
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Data Link Layer
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Network Layer
Third layer of the OSI model ~ Responsibilities
~
• • • • •
Source to destination delivery of data packets The global addressing of the data packets Routing data packets to final destination Network traffic control Fault handling
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Network Layer
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Transport Layer
Fourth layer of the OSI model ~ Responsibilities
~
• • • • •
Addressing using service points Segregation and Re-gathering Link control Transmission control Fault handling
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Transport Layer
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Session Layer
Fifth layer of the OSI model ~ Responsibilities
~
• Establishing communication between processes • Organization of data using check points
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Session Layer
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Presentation Layer
Sixth layer of the OSI model ~ Responsibilities
~
• Deals with syntax and semantics of data exchange • Encryption of data for security • Data compression to reduce rate of data transmission
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Presentation Layer
EC-Council
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Application Layer
Seventh layer of OSI model ~ Responsibilities
~
• • • •
Permits users access to the network Provides mail services Provides directory services Provides network virtual terminal services for communicating with remote hosts
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Application Layer
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Repeater
Electronic device that extends physical length of network • Function: Restores the signals before they become weak • Operates in OSI model at: – Physical layer ~ Advantages • Links segments of network of different medium ~ Disadvantages • Improper monitoring compromises entire network • Enhances traffic on the segments • No traffic segregation
~ EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Repeater
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Multiplexer
~ ~
Device that merges multiple electric signals into a single signal Function • Combines several inputs into a single output • Combines digital and analog signals
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Multiplexer
~
Advantages
• Multiplexer allows several digital signals to be transmitted using a single physical channel
~
Disadvantages
• Denial-of-Service weakness is present in some Multiplexer • Two streams of data competing for a single channel cause delay in transmission
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Routers
~ ~
Hardware device that determines the best path for data transmission Function
• Sends packets across several interconnected networks
~
Operates in OSI model at
• Physical layer • Data link layer • Network layer
~
Types
• • • • Backbone routers Broadband Routers IP Routers Remote Access Routers
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EC-Council
Network Device: Routers
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Network Device: Routers
~ Advantages
• Routers can link diverse media such as LAN, WAN and can transmit data • Routers avoid data collisions during transmission
~
Disadvantages
• The sent packets cannot be sort out causing additional transmission that increases cost • Routers do not have restricted access controls
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
EC-Council
Network Device: Brouter
Device that works as router and bridge ~ Operates like a bridge and forwards the data to the next segment ~ Functions
~
• Routes TCP/IP packets • Bridges data it cannot route
~
Advantages
• Uses physical address • Used for mixed-protocol traffic
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Hub
~
Device to connect devices in a network
• Function: Groups devices into a single network segment • Performance: Provides optimized and preset remote IP services to medium sized networks
~
Types
• Passive Hub • Active Hub
EC-Council
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Network Device: Hub
~
Advantages
• Computers and broadband modems connect to the network through the Hub • Prevents network crashes • Allows mixing of slow (10 Mb/sec) and fast (100 Mb/sec) Ethernet devices
~
Disadvantage
• Computers that are connected to isolated hubs, are isolated from the network
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Switch
Device which directs incoming data to a single output port from number of input ports ~ Function
~
• Directs data flow through specific path • Forwards data using MAC address embedded in each data packet
~
Advantages and Disadvantages
• Works efficiently than Hub • Packet sniffing is possible
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Bridge
~ ~ ~
Logical devices that segments LANs to decrease the traffic flow in the network Function
• Segregates traffic by dividing the network into segments
Operates in OSI Model at
• Physical layer • Data link layer
B r id g e
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Bridge
~
Advantages
• Used as filters • Segregation of networks into segments makes it trustworthy • Adaptable to higher protocols at MAC layer
~
Disadvantages
• Congestion due to high network traffics • Delays in transmission due to buffering of frames
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Modem
~ ~
Device that acts as both modulator and demodulator Function:
• Provides serial communication capabilities across phone lines
~
Speed of modem depends on the speed of Universal Asynchronous Receiver/Transmitter (UART) chip in the Computer Disadvantage:
• Transmission of data is slow
~
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Cables
~
Wires that connect network devices with each other across the network Function • Transfers raw data between network devices
~
~
Types of cable • Twisted pair • Coaxial • Optical fiber
~
Advantages and Disadvantages • Less problems with networking during bad weather • To take backup, there is a necessity of extra cables makes it expensive
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: ISDN Terminal Adapter
~ ~
Interfacing device Function
• Translates the signal between two digital adapters
~
Advantages
• Allows non-ISDN terminal at physical layer to communicate with ISDN network • Available as add-in expansion cards which are installed into computers
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Network Device: Network Card
~ ~
Device that joins computers in LANs Function
• Enables systems to connect to the network • Provides connectivity between nodes
~
Advantages
• Used in server clusters • NICs need not be fixed with physical cable • Used to both send and receive data
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Data Transmission Modes
~ Half -Duplex: ~ Full-
Duplex:
• Data is transmitted in LANs only one direction at a time • Broadband network supports half-duplex communication
• Data is transmitted in LANs simultaneously in both directions • Using suitable equipment full duplex communication can be obtained in some LAN’s and Ethernet
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Broadband and Baseband
~
Broadband
• Used in LAN’s • Transmits single signal through single cable simultaneously • Data transmitted is divided into distinct units called frames
~
Baseband
• Used in WANs • Transmits multiple signals through a single cable simultaneously
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
EC-Council
Segments and Backbone
Segments
• LAN’s comprising of networked terminals and user equipment • Used for large organization networks
~
~
Backbones
• Collection of LAN’s that are are interconnected to another LAN called Backbone • Acts like a channel facilitating communication between segments
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Client/Server and Peer-to-Peer Networking
~ Client/Server
Network
• In a network, some computers function as clients and some as servers
• Client:
– A computer that gains from the services provided by server
~ Peer-to-Peer
Network
• Server:
– A computer that offers services to a client
• Individual computers function as both clients and servers • Confined to small groups of computers and networks smaller than single LANs
EC-Council
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
Summary
~ ~ ~ ~ ~ ~
Network Topology is the arrangement of network devices Different types of topologies are Star Topology,Bus Topology,Ring Topology,Mesh Topology,Tree Topology The different types of networks are LAN,MAN,WAN OSI model covers all the features of network communications Networking devices are used for sharing the data or resources in a network Transmission mode is the path of the signal flow between two connected devices.It can of types HalfDuplex and Full- Duplex
Copyright © by EC-Council All Rights reserved. Reproduction is strictly prohibited
EC-Council
