Transcript Network Fundamentals

Network Fundamentals
Outline
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LANs
LAN Routers / Gateways
Wireless Connection
Firewalls
NAT
Network Protocols
Protocol Analysis
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Single Machine
• Security Risk: Physical Security
– Access to Machine (loss of equipment)
– Hack Machine (loss of information)
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Local Area Networks
• Security Risk: Physical Security
– Access to Machine (loss of equipment)
– Access to Hub / Switch (loss of information)
– Hack Machine (loss of information)
Hub / Switch
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Local Area Networks
(Routers / Gateways)
Internet
Router /
Gateway
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Local Area Networks
(Access Technologies)
• 56 Kbps Modem
– Establish a point-to-point connection to ISP
– Use PPTP (etc.) to establish an internet connection
– Private link
• DSL
– Full Time, Broadband connection
– Uses existing telecom facilities
– Private link
• Cable Modem
– Full Time, Broadband connection
– Shares existing cable TV facility with others
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Wireless Connection
WAP +
Router
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Internet
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Firewalls
• Provides a mechanism to control /
monitor access to the LAN
Firewall
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Internet
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Network Address Translation
• Many networks configured with private IP
addresses (10.0.0.0, 172.0.0.0, 192.168.0.0)
• Must convert to public address for Internet
access.
• May also have many hosts sharing limited
network addresses.
– If only 1 network address, then service is called Port
Address Translation - PAT
• NAT provides the translation services
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Network Address Translation
123.75.46.89
192.168.1.1
192.168.1.25
134.193.17.52
Web
Server
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NAT
Local
User
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Network Protocols
OSI Model
Internet
Application Layer
Presentation Layer
Application Layer
Session Layer
Transport Layer
TCP / UDP Layer
Network Layer
Internet Protocol
Data Link Layer
Physical Layer
Physical Layer
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LAN Physical Layer Protocols
• Ethernet
– 10base5
– 10base2
– 10baseT, 100baseT, 1000baseT
• Wireless Networks
– 802.11a
– 802.11b
– 802.11g
• Token Ring
• etc.
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WAN Physical Layer Protocols
• Telecommunications
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DS0, DS1, DS3
SONET
ISDN
etc.
• Metro Area Protocols
– Cellular Telephone
– FDDI
– WiMAX
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Network Layer Protocols
• Internet Protocol (IP)
– Routes packets across the network
– Manages packet fragmentation across
network
• Internet Control Message Protocol (ICMP)
– Provides support for IP and TCP
• Address Resolution Protocol (ARP)
– Provides address resolution between network
layer and data link layer addresses.
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Transport Layer Protocols
• Transmission Control Protocol (TCP)
– Provides reliable end-to-end packet transport
– Provides packet flow control
• User Datagram Protocol (UDP)
– Provides simplified end-to-end packet
transport
– No control overhead
– No packet fragmentation
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Application Support Protocols
• Provide Security
– SSH / SSL
– HTTPS
• Provide Compression / Data Translation
– zip , tar, compress
– MIME
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Application Layer Protocols
• Support specific network applications
– FTP
– WWW (HTTP, etc.)
– E-MAIL
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Protocol Analysis
• Packet Sniffers
– WireShark (Ethereal)
– Etherpeek
– EtherDetect
– Zx Sniffer
– AnalogX PacketMon
– Colasoft Capsa
– AirMagnet Enterprise (Wireless monitoring)
– etc.
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Wireshark Example
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Summary
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LANs
LAN Routers / Gateways
Wireless Connection
Firewalls
NAT
Network Protocols
Protocol Analysis
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