Network Basics
Learn fundamental networking concepts and terminology essential for cybersecurity professionals.
Communication
Protocols
Standards
A network is a collection of interconnected devices that can communicate and share resources. Understanding how data flows through networks is crucial for identifying security vulnerabilities and implementing appropriate protections.
# Network Fundamentals
network_basics = {
"definition": "Collection of interconnected devices sharing resources",
"core_components": {
"nodes": "Devices connected to the network (computers, servers, routers)",
"links": "Physical or wireless connections between nodes",
"protocols": "Rules governing communication between devices",
"services": "Applications and functions provided by the network"
},
"network_types": {
"LAN": "Local Area Network - limited geographic area",
"WAN": "Wide Area Network - large geographic area",
"MAN": "Metropolitan Area Network - city-wide coverage",
"PAN": "Personal Area Network - individual workspace"
},
"security_considerations": {
"attack_surface": "More devices = larger attack surface",
"data_in_transit": "Information vulnerable during transmission",
"access_control": "Need to control who can access what",
"monitoring": "Essential to detect suspicious activities"
}
}
OSI Model
Master the seven-layer OSI model and understand security implications at each layer.
OSI Model Layers (Bottom to Top):
• Physical (1): Electrical signals, cables, wireless
• Data Link (2): Frames, MAC addresses, switches
• Network (3): Packets, IP addresses, routing
• Transport (4): Segments, TCP/UDP, ports
• Session (5): Sessions, connections
• Presentation (6): Encryption, compression
• Application (7): User applications, protocols
Security at Each Layer:
Each OSI layer has specific security vulnerabilities and protective measures. Understanding these layers helps security professionals identify where attacks occur and implement appropriate defenses.
# OSI Model Security Analysis
osi_security = {
"layer_1_physical": {
"vulnerabilities": ["Cable tapping", "Signal jamming", "Physical access"],
"protections": ["Physical security", "Cable encryption", "Secure facilities"],
"examples": "Fiber optic cables, wireless encryption"
},
"layer_2_data_link": {
"vulnerabilities": ["MAC flooding", "ARP spoofing", "VLAN hopping"],
"protections": ["Port security", "ARP inspection", "VLAN segmentation"],
"protocols": "Ethernet, Wi-Fi, PPP"
},
"layer_3_network": {
"vulnerabilities": ["IP spoofing", "Routing attacks", "ICMP attacks"],
"protections": ["Firewalls", "IPSec", "Route filtering"],
"protocols": "IP, ICMP, OSPF, BGP"
},
"layer_4_transport": {
"vulnerabilities": ["Port scanning", "TCP hijacking", "DoS attacks"],
"protections": ["Port filtering", "Rate limiting", "Sequence randomization"],
"protocols": "TCP, UDP, SCTP"
}
}
Network Topologies
Understand different network topologies and their security implications for network design.
Common Topologies:
• Bus: Single cable backbone, vulnerable to single point of failure
• Star: Central hub/switch, hub failure affects all nodes
• Ring: Circular connection, break anywhere disrupts network
• Mesh: Multiple paths, provides redundancy and fault tolerance
• Hybrid: Combination of topologies for optimal design
Security Considerations:
Each topology has unique security characteristics. Star topologies centralize control but create single points of failure. Mesh networks provide redundancy but increase complexity and potential attack vectors.
# Network Topology Security Analysis
topology_security = {
"star_topology": {
"advantages": ["Centralized control", "Easy monitoring", "Isolated failures"],
"disadvantages": ["Single point of failure", "Hub/switch dependency"],
"security_features": ["Central monitoring", "Access control", "Traffic inspection"],
"common_use": "Most LANs, corporate networks"
},
"mesh_topology": {
"advantages": ["Redundancy", "Fault tolerance", "Load distribution"],
"disadvantages": ["Complex management", "Higher cost