NETWORK SECURITY ITEC 435
Agenda Chapter 2: Introduction to Networking
Introduction to Networking
Networking Fundamentals Reasons to Network Getting the Message Across Analog Information on an Analog Medium Analog Information on a Digital Medium Digital to Analog Digital to Digital
Networking Fundamentals (cont.) Combining Multiple Signals Frequency Division Multiplexing Time Division Multiplexing Wave Division Multiplexing
Networking Fundamentals (cont.) Impedance to Communication Attenuation Crosstalk Distortion Echo Impulse noise Jitter White noise
Types of Networks Networks Categorized by Components peer-to-peer (P2P) server based networks distributed multi-server networks Networks Categorized by Size local area network (LAN) metropolitan area network (MAN) Wide area network (WAN) Networks Categorized by Topology Star Bus Ring
Bus Ring Star
Types of Networks (cont.) Networks Categorized by Media guided/wired unguided/wireless
Standards Organizations The Internet Society (ISOC) Internet Assigned Numbers Authority (IANA) American National Standards Institute (ANSI) International Telecommunications Union (ITU) Institute of Electrical and Electronics Engineers (IEEE) Telecommunications Industry Association (TIA) International Organization for Standardization (ISO)
OSI Reference Model Host Layers Media Layers Data Unit Layer Function Data 7. Application Network process to application 6. Presentation Data representation and encryption 5. Session Interhost communication Segments 4. Transport End-to-end connections and reliability (TCP) Packets 3. Network Path determination and logical address (IP) Frames 2. Data Link Physical addressing (MAC & LLC) Bits 1. Physical Media, signal, and binary transmission
Physical Layer Twisted Pair Wire Shielded (STP) (token ring network) Unshielded (UTP) Cat 5e Cat 6 Cat 6a Cat 7 1 2 3 4 5 6 7 8
Physical Layer (cont.) Coaxial Cable Fiber-Optic Cable Wireless LAN Advantages Convenience Mobility Productivity Deployment Expandability Cost Disadvantages Security Range Reliability Speed
Physical Layer (cont.) Security Primary focus to protect the medium against unauthorized interception Eavesdropping Unauthorized access to connection devices like hubs Use of packet sniffers (i.e., special software used to capture and view packets) Fiber-optic cable is naturally resistant to eaves dropping
Data Link Layer (DLL) Data Link Layer primary layer for networking support First subnet layer Provides Addressing Packetizing Media access control Error control Some flow control DLL Protocols Ethernet Table 2-1 Wireless Ethernet Table 2-2 Token Ring Fiber Distributed Data Interface Asynchronous Transfer Mode Frame Relay PPP, PPTP, L2TP
Data Link Layer (cont.) Packet Framing Addressing Media Access Control Deterministic Approach Roll-call polling Go-ahead polling Contention Approach CSMA/CA and CSMA/CD Fist-come, first-served basis
Network Layer Packetizing 0 bits Header Header 32 bits Type of service Type of service version length (8 bits) (16 bits) (4 bits) (4 bits) Identification (16 bits) Flags (3 bits) Header checksum (16 bits) Time to live (8 bits) Protocol (8 bits) Header checksum (16 bits) Source IP address (32 bits) Destination IP address (32 bits) Options Data
Network Layer (cont.) Addressing Figure 2-17 Class A Class B Class C Class D (reserved) Class E (reserved)
Required Reading pp 66 74 Review Table 2-3 IP Address Classes Network Address Translation (NAT) Subnetting Routing Gateway Protocol Boarder Gateway Protocol Network layer security Transport Layer Error Control Security Table 2-4 Well-Known Port Numbers Session Layer Presentation Layer
Application Layer Table 2-5 Common Application Layer Protocols HTTP IMAP, POP, SMTP FTP RPC Application Layer Security