Notes - MIECT
Segurança Em Redes De Comunicações
Notes - MIECT
Segurança Em Redes De Comunicações
  • Segurança Em Redes De Comunicações
  • Corporate Networks Topics
    • Objectives of Network Design
    • Equipments
    • Hierarchical Network Model
    • Modular Network Design
    • Designing the Access Layer
    • Designing the Core Layer
    • Virtual LANs
      • VLANs on Access Points
    • Spanning Tree Protocol
    • IP Routing Overview
  • Introduction to Network Security
    • Type of Attacks
    • Attacks Phases
      • Infiltration Phase
      • Propagation Phase
      • Aggregation and Exfiltration Phase
    • Defenses
    • Security Metrics
  • Network Access Control
    • AAA Architecture
      • TACACS+
      • RADIUS
      • DIAMETER
    • IEEE 802.11 services
    • Joining a BSS
      • WLAN Frames
      • Joining BSS with AP
    • WPA and 802.11i (WPA2)
  • Network Flow Control
    • Network Security Systems
    • Firewalls
    • High-Availability
    • Load Balancing Firewall Load
    • Best Practices and Recommendations
    • IP Spoofing
    • Half-Open TCP Connection Problem
    • DDoS Mitigation at Source
    • Cisco’s Access Control Lists (ACL)
    • Linux IPTables
    • Control By Analysis of Higher Layers
  • Secure Communications
    • Public Key Infrastructure (PKI)
    • X.509 Certificate Contents
    • Traffic Tunnel Concept
      • Next Hop Resolution Protocol (NHRP)
      • Hub-Spoke vs. Spoke-Spoke
    • IPSec
    • Establishing SA and Cryptographic Keys
    • Virtual Private Networks (VPN)
    • Management of Asymmetric Keys
  • Remote Access
    • Remote Access
    • IPsec NAT Transversal
    • Integration with Flow Control
  • Intrusion Detection and Prevention
    • Intrusion Detection and Prevention
    • Host-Based vs. Network-Based
    • Signature vs. Anomaly Based
    • Network Deployment
  • Network Monitoring SIEM
    • Core and End-to-End Monitoring
    • Node Monitoring
    • End-User/Host/App Monitoring
    • Server/Service/Cloud Monitoring
    • Per-Service Detailed Monitoring
    • Data Sources
      • SNMP
      • NetFlow
    • Network Passive Probing Packet Capturing
    • Remote CLI Access
    • Log Files Access
      • Log Management Systems (LMS)
      • Security Information and Events Management (SIEM)
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  1. Network Access Control
  2. Joining a BSS

Joining BSS with AP

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Last updated 2 years ago

Scanning

A station willing to join a BSS must get in contact with the AP. This can happen through:

  • Passive scanning.

    • The station scans the channels for a Beacon frame that is sent periodically from an AP to announce its presence and provide the SSID, and other parameters for WNICs within range.

  • Active scanning (the station tries to find an AP).

    • The station sends a Probe Request frame - Sent from the station when it requires information from another station.

    • All APs within reach reply with a Probe Response frame - Sent from an AP containing capability information, supported data rates, etc., after receiving a probe request frame.

Association

Once a station is authenticated, it starts the association process, i.e., information exchange about the AP/station capabilities and roaming.

  • STA → AP: Associate Request frame.

    • Enables the AP to allocate resources and synchronize. The frame carries information about the WNIC, including supported data rates and the SSID of the network the station wishes to associate with.

  • AP → STA: Association Response frame.

    • Acceptance or rejection of an association request. If it is an acceptance, the frame will contain information such as association ID and supported data rates.

  • New AP informs old AP (if it is a handover).

Only after the association is completed, a station can transmit and receive data frames.

Station “IntelCor*” sending data to station “D-LinkIn*” (via AP).

Frame captured between station “IntelCor*” and AP (“Cisco*”).

Beacon frame
Probe request
Probe response
Association request - from Station
Association response - from AP
Data frame