The document discusses the characteristics and security issues of wireless LANs (WLANs). It describes the advantages and disadvantages of WLANs, as well as their design goals and transmission technologies. It then discusses some specific wireless security issues for WLANs, including interception of radio signals, reliance on shared public infrastructure, and risks from rogue access points and war driving. Finally, it provides an overview of the IEEE 802.11 standard for WLANs, including its network architectures, transmission methods like CSMA/CA, frame types, and security features.
The Internet of Things if growing, but how can you build your own connected objects?
Together with MQTT, CoAP is one of the popular IoT protocols. It provides answers to the typical IoT constraints: it is bandwidth efficient and fits in constrained embedded environment while providing friendly and discoverable RESTful API.
This tutorial aims at giving you a hands-on experience with CoAP by showing you the power and simplicity of the Eclipse Californium library for developing real world IoT application.
Agenda:
- Introduction to CoAP
- Live discovery of connected CoAP objects using the Copper plugin for Firefox
- Presentation of more advanced CoAP topics (proxy, resource directory, device management with LWM2M)
- Presentation of Eclipse Californium, a CoAP library for Java
- Exercise: complete the provided Java code to create your own Internet of Things... thing!
DHCP Stands for Dynamic Host Configuration Protocol.
DHCP is a protocol that automatically provides an IP host with its IP address and other related configuration information ( subnet mask, default gateway,DNS etc. )
Works on Protocol UDP port no 67 and 68.
The 3 aspects of network performance managementManageEngine
Do you think it is enough to monitor the device or link availability and performance to manage your network? But that is just the first step!
Go through this slide to understand the 3 aspects of network performance management.
The Internet of Things if growing, but how can you build your own connected objects?
Together with MQTT, CoAP is one of the popular IoT protocols. It provides answers to the typical IoT constraints: it is bandwidth efficient and fits in constrained embedded environment while providing friendly and discoverable RESTful API.
This tutorial aims at giving you a hands-on experience with CoAP by showing you the power and simplicity of the Eclipse Californium library for developing real world IoT application.
Agenda:
- Introduction to CoAP
- Live discovery of connected CoAP objects using the Copper plugin for Firefox
- Presentation of more advanced CoAP topics (proxy, resource directory, device management with LWM2M)
- Presentation of Eclipse Californium, a CoAP library for Java
- Exercise: complete the provided Java code to create your own Internet of Things... thing!
DHCP Stands for Dynamic Host Configuration Protocol.
DHCP is a protocol that automatically provides an IP host with its IP address and other related configuration information ( subnet mask, default gateway,DNS etc. )
Works on Protocol UDP port no 67 and 68.
The 3 aspects of network performance managementManageEngine
Do you think it is enough to monitor the device or link availability and performance to manage your network? But that is just the first step!
Go through this slide to understand the 3 aspects of network performance management.
this presentation covers all the main points that need to know about vpn. That includes the types,overview,future plans,advantage,disadvantage,working of vpn.
It is a PPT on Wireless LAN Security,made by ARPIT BHATIA(student of Sri Guru Nanak Public School, Adarsh Nagar) for Informatics Practices project.It has all necessary information with pictures about the wireless LAN. This PPT is made only for Educational Purpose.
Topics in wireless communication for project and thesisTechsparks
There are various topics in wireless communication which you can choose for your thesis.
You can call on this number for any query on this topic : +91- 9465330425
http://www.techsparks.co.in/thesis-topics-in-wireless-communication/
High level overview of CoAP or Constrained Application Protocol. CoAP is a HTTP like protocol suitable for constrained environment like IoT. CoAP uses HTTP like request response model, status code etc.
1. An introduction of LAN.
2. An introduction of VLAN.
3. Properties of VLAN.
4. Types of VLAN.
5. VLAN Identification Method
6. VLAN Trunking Protocol.
7. Inter-VLAN routing.
this presentation covers all the main points that need to know about vpn. That includes the types,overview,future plans,advantage,disadvantage,working of vpn.
It is a PPT on Wireless LAN Security,made by ARPIT BHATIA(student of Sri Guru Nanak Public School, Adarsh Nagar) for Informatics Practices project.It has all necessary information with pictures about the wireless LAN. This PPT is made only for Educational Purpose.
Topics in wireless communication for project and thesisTechsparks
There are various topics in wireless communication which you can choose for your thesis.
You can call on this number for any query on this topic : +91- 9465330425
http://www.techsparks.co.in/thesis-topics-in-wireless-communication/
High level overview of CoAP or Constrained Application Protocol. CoAP is a HTTP like protocol suitable for constrained environment like IoT. CoAP uses HTTP like request response model, status code etc.
1. An introduction of LAN.
2. An introduction of VLAN.
3. Properties of VLAN.
4. Types of VLAN.
5. VLAN Identification Method
6. VLAN Trunking Protocol.
7. Inter-VLAN routing.
The Ethernet LAN has many security weaknesses when facing attacks externally and internally. This Presentation will helps user How they can Secure there LAN Network From unwanted threats
This presentation describes the WEP issued in the original IEEE 802.11 and points out it's weakness and how can attacks be executed. Also, it summarizes the best practices to introduce security to the Wireless enviroment.
Is your wireless network more secure than your wired network? In this session, we'll discuss how to use industry standard techniques to provide secure wired access. This includes using policies and RADIUS/RADIUS CoA to ensure that ports used for Wi-Fi APs, IoT devices, printers and IP phones are protected against unwanted use by employees, guests, and contractors. The days of dedicated ports assigned to VLANs are over! By using a 'universal ports tied to policies’ model, network access is based on dynamic enforcement rules. These techniques work across popular wired infrastructure from HPE, Cisco, and others.
Wireless LAN Security, Policy, and Deployment Best PracticesCisco Mobility
The current state of wireless security, covering wireless device access, preventing rogue threats and addressing wireless attacks. Special focus on device profiling and policy covering how to prevent unauthorized (such as smartphones and tablets) from accessing the network. Learn More: http://www.cisco.com/go/wireless
1ST DISIM WORKSHOP ON ENGINEERING CYBER-PHYSICAL SYSTEMSHenry Muccini
The University of L'Aquila, Italy, has organized an internal meeting on Engineering Cyber-Physical Systems (26 Jan 2016). About 35 colleagues from the DISIM (Information Engineering, Computer Science, and Mathematics) have participated and made presentations.
This SlideShare collects all the presentations.
If interested to future events, feel free to contact us:
Alessandro D’Innocenzo – alessandro.dinnocenzo@univaq.it -
Henry Muccini - henry.muccini@univaq.it
The local area technologies as 1-WLAN(Wireless Local Area Network) with moderate bandwidth. And WiMax
2.The large area technologies as GSM, GPRSor UMTS, LTEwhich have much higher bandwidth.
Understanding WiFi Security Vulnerabilities and SolutionsAirTight Networks
These slides include discussion on important Wi-Fi security issues and the solutions available to address them. Enterprises which need to secure their networks from Wi-Fi threats in order to protect their information assets, prevent unauthorized use of their network, enforce no-Wi-Fi zones, and meet regulatory compliance for themselves and their clients will benefit from this discussion.
The IEEE 802 is a family of IEEE standards dealing with Local Area Networks and Metropolitan Area Networks. The IEEE 802 family of standards is maintained by the IEEE 802 LAN/MAN Standards Committee (LMSC).
The most widely used standards are for the Bridging and Virtual Bridged LANs (802.1), Ethernet family (802.3), Token Ring (802.5) and Wireless LAN (802.11).
This is a ppt about the recent trends in tech and wireless communication. As the is good document to read we are requesting to study the wireless communal harmony and peace to you. Aster that I have a great day and I will be available from June to September to December to February to the same here to visit our frequently asked questions about HTML5.
And ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha Akshar cholk Thai ne na jato ko bhi 6 baje uthta hai ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye shikhar ki aur batao ki nai dunia epaper ab naye 5.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Software Delivery At the Speed of AI: Inflectra Invests In AI-Powered QualityInflectra
In this insightful webinar, Inflectra explores how artificial intelligence (AI) is transforming software development and testing. Discover how AI-powered tools are revolutionizing every stage of the software development lifecycle (SDLC), from design and prototyping to testing, deployment, and monitoring.
Learn about:
• The Future of Testing: How AI is shifting testing towards verification, analysis, and higher-level skills, while reducing repetitive tasks.
• Test Automation: How AI-powered test case generation, optimization, and self-healing tests are making testing more efficient and effective.
• Visual Testing: Explore the emerging capabilities of AI in visual testing and how it's set to revolutionize UI verification.
• Inflectra's AI Solutions: See demonstrations of Inflectra's cutting-edge AI tools like the ChatGPT plugin and Azure Open AI platform, designed to streamline your testing process.
Whether you're a developer, tester, or QA professional, this webinar will give you valuable insights into how AI is shaping the future of software delivery.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Connector Corner: Automate dynamic content and events by pushing a buttonDianaGray10
Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But there’s more:
In a second workflow supporting the same use case, you’ll see:
Your campaign sent to target colleagues for approval
If the “Approve” button is clicked, a Jira/Zendesk ticket is created for the marketing design team
But—if the “Reject” button is pushed, colleagues will be alerted via Slack message
Join us to learn more about this new, human-in-the-loop capability, brought to you by Integration Service connectors.
And...
Speakers:
Akshay Agnihotri, Product Manager
Charlie Greenberg, Host
2. Characteristics of WLANs
• Advantages
Flexibility, Planning, Design, Robustness, Cost, ...
• Disadvantages
Qos, Proprietary Solutions, Frequency Restrictions, Safety And Security
• Design goals of WLANs
Global Operation, Low Power, License-free Operation, Robust
Transmission Technology, Ad-hoc Operation, Transparency To Higher
Layers, ...
• Transmission technologies in WLAN
Infrared
Radio waves
2
3. IEEE 802.11
• Some Wireless Security Issues:
Radio signals travel through the open atmosphere where they can be
intercepted by individuals who are constantly on the move, making them
difficult to track down.
Wireless solutions are universally dependent on public-shared
infrastructure, where there might be less control and knowledge about
the security discipline used.
Rogue access points can jeopardize everything a company spends on
firewalls, access control, and other security software.
War dialing, also known as war driving, poses a significant problem.
– a technique of using a modem to automatically scan a list of telephone
numbers, usually dialing every number in a local area code to search for
computers (Ref: Wikipedia)
3
4. Characteristics of WLANs
• Infrastructure vs. Ad-hoc Networks
Infrastructure network
AP wired network AP
AP AP
Ad-hoc network
4
5. Characteristics of WLANs
• Architecture of an Infrastructure
Network: 802.11 LAN
802.x LAN
– Station (STA)
• terminal with access mechanisms to the STA1
wireless medium and radio contact to
the access point BSS1
– Basic Service Set (BSS) Portal
• group of stations using the same radio Access
frequency Point
– Access Point (AP) Distribution System (DS)
• station integrated into the wireless LAN
and the distribution system Access
ESS Point
– Portal
• bridge to other (wired) networks BSS2
– Distribution System (DS)
• interconnection network to form one
logical network STA2 STA3
– Extended Service Set (ESS) 802.11 LAN
• comprised of several BSS
5
6. Characteristics of WLANs
802.11 LAN
• Architecture of an Ad-hoc Network:
– Direct communication within a limited STA1 STA3
range
IBSS1
• Station (STA):
– terminal with access mechanisms to STA2
the wireless medium
• Independent Basic Service Set (IBSS):
– group of stations using the same
radio frequency IBSS2
STA5
STA4
802.11 LAN
6
6
8. IEEE 802.11
• IEEE
– Institute of Electrical and Electronics Engineers
• 802.11
– Family of standards set forth by IEEE to define the specifications for
wireless LANs
– Specifications for
• Medium Access Control (MAC)
• Physical Layer (PHY)
• IEEE 802.x ?
– Local, high-speed connectivity for fixed, portable and moving STAs
8
8
9. IEEE 802.11
• IEEE 802.11 vs. IEEE 802.3
– Similarity
• Same LLC -> No difference for upper layer protocols
– Differences
• WLAN is not private
• WLAN is exposed to more environmental problems
• IEEE 802.11 PHY has NO collision detection
» “Hidden Node Problem”
9
9
10. IEEE 802.11
mobile terminal
infrastructure
network
access point
application application
TCP TCP
IP IP
LLC LLC LLC
802.11 MAC 802.11 MAC 802.3 MAC 802.3 MAC
802.11 PHY 802.11 PHY 802.3 PHY 802.3 PHY
10
10
11. IEEE 802.11
• CSMA Medium Access – “CD” (Ethernet)
– If media is sensed idle, transmit
– If media is sensed busy, wait until idle and then transmit immediately
• If a collision is detected, stop transmitting.
• Reschedule transmission according to an exponential back-off
• CSMA Medium Access – “CA” (802.11)
– Would like to use CSMA but cannot use CD!
• Use Collision Avoidance (CA) instead
11
11
12. IEEE 802.11
• CSMA/CA – Access Method
• Station ready to send starts sensing the medium (Carrier Sense
based on CCA, Clear Channel Assessment)
• If the medium is free for the duration of an Inter-Frame Space (IFS),
the station can start sending (IFS depends on service type)
• If the medium is busy, the station has to wait for a free IFS, then the
station must additionally wait a random backoff time (collision
avoidance, multiple of slot-time)(Distributed Coordination Function
(DCF))
• Backoff Time = Random () x aSlotTime
• If another station occupies the medium during the backoff time of the
station, the backoff timer stops (fairness)
12
19
13. IEEE 802.11
contention window
(randomized back-off
DIFS DIFS mechanism)
Medium Busy next frame
Direct Access if t
medium is free ≥ DIFS
slot time
Distributed Co-ordination Function (DCF): DCF employs a CSMA/CA with binary
exponential backoff algorithm.
DCF Interframe Space (DIFS)
DIFS = SIFS (2 * Slot time)
(SIFS: Short Interframe Space (SIFS), is the small time interval
between the data frame and its acknowledgment) 13
20
14. IEEE 802.11
• Hidden Node Problem
STAC STAB STAA
B B
14
21
15. IEEE 802.11
• MAC Layer – Access Mechanisms
– Distributed Coordination Function (DCF) with RTS/CTS handshake
• RTS (Request to Send), CTS (Clear To Send) helps determine who
else is in range or busy (collision avoidance) -> CSMA/CA
• Sender A sends RTS, receiver B sends CTS
– Nodes who hear CTS cannot transmit concurrently with A (red
region)
– Nodes who hear RTS but not CTS can transmit (green region)
– Sender A sends data frame, receiver B sends ACK
– Nodes who hear the ACK can now transmit
15
22
16. IEEE 802.11
802.11 MAC Access Mechanism – RTS/CTS
STAC STAB STAA STAD STAx
X
B
16
17. IEEE 802.11
• DFW MAC - DCF CSMA/CA (Distributed Foundation Wireless MAC)
The Network Allocation Vector (NAV) is virtual Short Inter-Frame Space (SIFS) is the shortest of the interface
carrier sensing mechanism used with wireless spaces. SIFS is used with ACK and CTS frames
network protocols. The NAV may be thought of as
a counter, which counts down to zero at a uniform
rate. When the counter is zero, the virtual CS
indication is that the medium is idle; when nonzero,
the indication is busy. The medium shall be
determined to be busy when the STA is
transmitting.
DIFS
RTS data
sender
SIFS SIFS
SIFS
CTS ACK
receiver
NAV (RTS) DIFS
other data
NAV (CTS)
stations
t
defer access
» contention
station can send RTS with reservation parameter after waiting for DIFS
(reservation determines amount of time the data packet needs the medium)
» acknowledgement via CTS after SIFS by receiver (if ready to receive)
» sender can now send data at once, acknowledgement via ACK
17
» other stations store medium reservations distributed via RTS and CTS
24
18. IEEE 802.11
• MAC Frames
– Types
• control frames, management frames, data frames
– Sequence numbers
• important against duplicated frames due to lost ACKs
– Addresses
• receiver, transmitter (physical), BSS identifier, sender
(logical)
– Miscellaneous
• sending time, checksum, frame control, data
18
25
19. IEEE 802.11
MPDU Format (Fields)
• MAC Frames MAC Control : contains any protocol
control information
• MAC Protocol Data Unit (MPDU) Destination MAC Address
Source MAC Address
MAC Service Data Unit : The data from
the next higher layer
CRC : Cyclic Redundancy Check; also
known as Frame Check Sequence (FCS)
field.
PHY IEEE 802.11 Data CRC
bytes
2 2 6 6 6 2 6 0-2312 4
Frame Address Address Address Sequence Address
Duration/ID Data CRC
Control 1 2 3 Control 4
bits 2 2 4 1 1 1 1 1 1 1 1
Protocol To From More Power More
Type Subtype Retry WEP Order
version DS DS Frag Mgmt Data
19
26
20. IEEE 802.11
• Valid MAC Address Format
Function To From Address 1 Address 2 Address 3 Address 4
DS DS
Ad-hoc 0 0 DA SA BSSID -
From AP 0 1 DA BSSID SA -
To AP 1 0 BSSID SA DA -
Within 1 1 RA TA DA SA
DS
Service Set Identifier (SSID) is the name of a WLAN
Basic Service Set (BSS):
• In infrastructure mode, a single AP together with all associated STAs
is called a BSS
• In ad hoc mode a set of synchronized stations, one of which acts as master,
forms a BSS.
• The most basic BSS consists of one access point and one station.
Basic Service Set Identifier (BSSID):
• Uniquely identifies each BSS
• The BSSID is the MAC address of the wireless access point (WAP). 20
27
22. IEEE 802.11
• MAC Management
– Synchronization
• try to find a LAN, try to stay within a LAN
• timer etc.
– Power management
• sleep-mode without missing a message
• periodic sleep, frame buffering, traffic measurements
– Association/Reassociation
• integration into a LAN
• roaming, i.e. change networks by changing access points
• scanning, i.e. active search for a network
– MIB - Management Information Base
• managing, read, write
22
29
23. IEEE 802.11
• Synchronization
beacon interval
access B B B B
point
busy busy busy busy
medium
value of the timestamp beacon frame t
B
beacon interval
B1 B1
station1
B2 B2
station2
busy busy busy busy
medium
value of the timestamp t 23
B beacon frame random delay
30
24. IEEE 802.11
• MAC Power Management
– Idea: switch the transceiver off if not needed
– States of a station: sleep and awake
– Timing Synchronization Function (TSF)
• stations wake up at the same time
– Infrastructure
• Traffic Indication Map (TIM)
– list of unicast receivers transmitted by AP
• Delivery Traffic Indication Map (DTIM)
– list of broadcast/multicast receivers transmitted by AP
– Ad-hoc
• Ad-hoc Traffic Indication Map (ATIM)
– announcement of receivers by stations buffering frames
– more complicated as there is no central AP
– collision of ATIMs possible (scalability?)
24
31
25. IEEE 802.11
• Power-saving with wake-up pattern
TIM interval DTIM interval
Infrastructure network
access D B T T d D B
point
busy busy busy busy
medium
p d
station
t
T TIM D DTIM awake
data transmission
B broadcast/multicast p Power d to/from the station
Save 25
poll
32
26. IEEE 802.11
• Roaming
– No or bad connection? Then perform:
– Scanning
• scan the environment, i.e., listen into the medium for beacon signals or send
probes into the medium and wait for an answer
– Reassociation Request
• station sends a request to one or several APs
– Reassociation Response
• success: AP has answered, station can now participate
• failure: continue scanning
– AP accepts Reassociation Request
• signal the new station to the DS
• the DS updates its data base (i.e., location information)
• typically, the DS now informs the old AP so it can release resources
26
33
27. IEEE 802.11
• Connection set-up time
• IEEE 802.11b – Connectionless/always on
• Data rate
– 1, 2, 5.5, 11 Mbit/s, depending • Quality of Service
on SNR
– Typical best effort, no
– User data rate max. approx. 6 guarantees (unless polling is
Mbit/s used, limited support in
products)
• Transmission range
– 300m outdoor, 30m indoor • Manageability
– Max. data rate ~10m indoor – Limited (no automated key
distribution, symmetrical
Encryption)
• Frequency
– Free 2.4 GHz ISM-band
• Advantages/Disadvantages
– Advantage: many installed
• Security systems, lot of experience,
– Limited, WEP insecure, SSID available worldwide, free ISM-
band, many vendors, integrated
in laptops, simple system
• Cost – Disadvantage: heavy
– 100€ adapter, 250€ base station, interference on ISM-band, no
dropping service guarantees, slow relative
speed only
• Availability
– Many products, many vendors 27
34
28. IEEE 802.11
• IEEE 802.11a
• Data rate
– 6, 9, 12, 18, 24, 36, 48, 54 Mbit/s, • Connection set-up time
depending on SNR
– User throughput (1500 byte packets): 5.3 – Connectionless/always on
(6), 18 (24), 24 (36), 32 (54) • Quality of Service
– 6, 12, 24 Mbit/s mandatory – Typical best effort, no
guarantees (same as all 802.11
• Transmission range products)
– 100m outdoor, 10m indoor
• Manageability
– Limited (no automated key
• Frequency distribution, symmetrical
Encryption)
– Free 5.15-5.25, 5.25-5.35, 5.725-5.825
GHz ISM-band • Advantages/Disadvantages
• Security – Advantage: fits into 802.x
standards, free ISM-band,
– Limited, WEP insecure, SSID available, simple system, uses
less crowded 5 GHz band
• Cost
– 280€ adapter, 500€ base station – Disadvantage: stronger shading
due to higher frequency, no
• Availability QoS
– Some products, some vendors
28
35
29. IEEE 802.11
• Other IEEE 802.11 flavors
– 802.11d: Regulatory Domain Update
– 802.11e: MAC Enhancements – QoS
• Enhance the current 802.11 MAC to expand support for applications with
Quality of Service requirements, and in the capabilities and efficiency of the
protocol.
– 802.11f: Inter-Access Point Protocol
• Establish an Inter-Access Point Protocol for data exchange via the distribution
system.
– 802.11g: Data Rates > 20 Mbit/s at 2.4 GHz; 54 Mbit/s, OFDM
– 802.11h: Spectrum Managed 802.11a (DCS, TPC)
– 802.11i: Enhanced Security Mechanisms
• Enhance the current 802.11 MAC to provide improvements in security.
– Study Groups
• Radio Resource Measurements
• High Throughput
29
36
30. WLAN Security
• General Methods
MAC Filter
SSID Cloaking
WEP
• General Attacks
30
36
31. Mac Filter
• Filter authorized devices based on MAC-address
(The network card physical address)
• It’s easy to spoof MAC-addresses
The address length is only 12-digit long
Easy to eavesdrop on a wlan connection and find out active hosts
31
32. SSID Cloaking
• Every WLAN network has a associated SSID-name
• By SSID Cloaking the access point will not broadcast its SSID
• Actually the SSID broadcasted from the access point are null
• Host can probe to this null SSID (called active scanning) and then
be-able to find or cloaked networks
• This will NOT give you a hidden WLAN
32
33. Wired Equivalent Privacy (WEP)
• Uses a 64-bit key (some vendors use a 128-bit key but this is not
standardised).
• Uses a data integrity checksum called Integrity Check Value (ICV)
• Uses an Internal Vector IV that has the length of 24-bits
• The 64-bit key are a combination of the IV (24-bits) and a static key
(40 bits)
24-bit IV 40-bit static key
33
34. WEP Weakness
• IV collisions attack
The IV is always sent in clear text and are different in every frame the IV
will eventually repeat over a period of time (every 16 million packet)
When IV collisions occur a cracker can with easy means recover the
secret key
• Weak key attack
Sometimes a weak IV is generated which makes cracking of the secret
key easy
• Re-injection attack
A cracker uses tools to inject packets that accelerate the collisions of
weak IVs
• Bit-flipping attack
Due to problems in the ICV a cracker can tamper with encrypted
packets
With a combination of the first three, existing tools can
crack a “secure” WEP network in 5 minutes 34
35. Dynamic WEP Encryption
• Due to the weakness of static WEP, dynamic WEP were introduced
• Dynamic WEP encryption changes the encryption key (re-keying)
automatically so often that it is harder (impossible?) for a cracker to
gather enough information to make a successful decryption of the
key
• Can be configured and implemented in many ways
Per-user encryption
Per-frame encryption
35
36. Wi-Fi Protected Access - WPA
• Developed in 2004 to be a successor of WEP and cover the flaws
within WEP
• WPA became a standard before the IEEE standard 802.11i where
released
• Supports TKIP/RC4 dynamic encryption
Authentication using ether of
– 802.1X/EAP for Enterprise
– Pre-shared key for SOHO
Link securing using dynamic keys
– Per-link
– Per-frame
36
FREDRIK ERLANDSSON
37. WPA2
• When 802.11i were introduced the WPA2 certification became a
more complete implementation of the 802.11i
• Supports both CCMP/AES and TKIP/RC4
802.1X/EAP for Enterprise
Pre-shared key for SOHO
37
38. Wireless Attacks
• Rouge Access Point
A WiFi access point is installed by a clueless user on the network
Uncontrolled and unmonitored
Provides a open hole for drive by hackers to the internal network
• Peer-to-Peer Attacks
Due to poorly configured endpoints (hosts) two host can connect to each
other and hence no central security policy can be used they can full
access to each others services
• Wireless Hijacking - Man in the middle attack
A cracker uses his computer as a AP and fools users to connect to him
instead of a real AP
The cracker can see all data
• Eavesdropping
Everything sent on a wireless network can be intercepted by anyone
within range.
– Wardriving 38
40. HIPERLAN
• ETSI standard
– European standard, cf. GSM, DECT, ...
– Enhancement of local Networks and interworking with
fixed networks
– integration of time-sensitive services from the early
beginning
• HIPERLAN (HIgh PErformance Radio LAN)
family of standards
– one standard cannot satisfy all requirements
• range, bandwidth, QoS support
• commercial constraints
– HIPERLAN 1 standardized since 1996 – no products!
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41. HIPERLAN
• HIPERLAN Standardization Scope
higher layers
medium access logical link
network layer
control layer control layer
channel access medium access
data link layer
control layer control layer
physical layer physical layer physical layer
IEEE 802.11 layers OSI layers HIPERLAN layers
41
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42. HIPERLAN
• HIPERLAN family – An Overview
HIPERLAN 1 HIPERLAN 2 HIPERLAN 3 HIPERLAN 4
access to ATM wireless local point-to-point
Application wireless LAN fixed networks loop wireless ATM
Frequency 5.1 – 5.3 GHz 17.2 – 17.3 GHz
decentralized, cellular, point-to-
Topology ad-hoc/infrastr. centralized multipoint point-to-point
Antenna omni-directional directional
Range 50 m 50 – 100 m 5000 m 150 m
QoS statistical ATM Traffic Classes (VBR, CBR, ABR, UBR)
Mobility < 10 m/s stationary
Interface Conventional LAN ATM networks
Data Rate 23.5 MBit/s > 20 MBit/s 155 MBit/s 42
Power Conservation
2007-12-17 yes
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43. HIPERLAN
• HIPERLAN/2
– short range (< 200 m), indoor/campus, 25 Mbit/s user data rate
– access to telecommunication systems, multimedia applications, mobility
(< 10 m/s)
• HIPERACCESS
– wider range (< 5 km), outdoor, 25 Mbit/s user data rate
– fixed radio links to customers (“last mile”), alternative to xDSL or cable
modem, quick installation
– Several (proprietary) products exist with 155 Mbit/s plus QoS
• HIPERLINK – currently no activities
– intermediate link, 155 Mbit/s
– connection of HIPERLAN access points or connection between
HIPERACCESS nodes
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44. HIPERLAN
• HiperLAN2
– Official name: BRAN HIPERLAN Type 2
• H/2, HIPERLAN/2 also used
– High data rates for users
• More efficient than 802.11a
– Connection oriented
– QoS support
– Dynamic Frequency Selection (DFS)
– Security support
• Strong encryption/authentication
– Mobility support
– Network and application independent
• convergence layers for Ethernet, IEEE 1394, ATM, 3G
– Power save modes
– Plug and Play
44
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46. HIPERLAN
• HiperLAN2 - Centralized vs. Direct mode
AP AP/CC
control control
data control
data
MT1 MT2 MT1 MT2 MT1 MT2 + CC
data
control
Centralized Direct
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47. HIPERLAN
• Protocol stack in HiperLAN2 (in AP)
Higher layers
DLC control DLC user
Convergence layer
SAP SAP
Radio link control sublayer Data link control -
basic data
transport function
Radio DLC
Association
resource connection
control Scope of
control control
HiperLAN2
Error standards
control
Radio link control
Medium access control
Physical layer
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48. HIPERLAN
• HiperLAN2 MAC Frames
2 ms 2 ms 2 ms 2 ms
TDD,
500 OFDM
MAC frame MAC frame MAC frame MAC frame ... symbols/frame
random
broadcast phase downlink phase uplink phase
access phase
variable variable variable
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49. HIPERLAN
• HiperLAN2 – DLC
– Six transport channels for data transfers in the different phases
• Broadcast channel (BCH) – 15 bytes
• Frame channel (FCH) – multiple 27 bytes
• Access feedback channel (ACH) – 9 bytes
• Long transport channel (LCH) – 54 bytes
• Short transport channel (SCH) – 9 bytes
• Random channel (RCH) – 9 bytes
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50. HIPERLAN
• Valid configuration of MAC frames
2 ms 2 ms 2 ms 2 ms
MAC frame MAC frame MAC frame MAC frame ...
random
broadcast downlink uplink access
BCH FCH ACH DL phase DiL phase UL phase RCHs Valid combinations
of MAC frames for
BCH FCH ACH DiL phase UL phase RCHs a single sector AP
BCH FCH ACH DL phase UL phase RCHs
BCH FCH ACH UL phase RCHs
BCH FCH ACH DL phase DiL phase RCHs
BCH FCH ACH DiL phase RCHs
BCH FCH ACH DL phase RCHs
50
BCH FCH ACH RCHs
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51. Summary
• All WLANs suffer from limitations but allow for a new
degree of freedom for their users
• Standard insures interoperability!
– WiFi Alliance (Wireless Fidelity) insures interoperability of 802.11
products (former WECA)
• HiperLAN2 comprises many interesting features but no
products are available yet
• Technologies that might influence WLANs
– Wireless Sensor Networks
– Radio Frequency Identification (RFID)
– Ultra Wide Band Technology (UWB)
• Most likely the typical mobile devices of tomorrow will
comprise several technologies
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52. Overlay Networks – Global goal
Integration of heterogeneous fixed and mobile
networks with varying transmission characteristics
regional
vertical
handover
metropolitan area
campus-based
horizontal
handover
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53. References
• http://www.ieee802.org/11
• http://grouper.ieee.org/groups/802/11/Reports
• http://www.csrc.nist.gov/encryption/aes
• http://www.hiperlan2.com
• http://www.etsi.org
• IEEE, “Wireless LAN Medium Access Control (MAC) and Physical
Layer (PHY) specifications” IEEE 802.11, IEEE (1999)
• ETSI, “Radio Equipment and Systems (RES), High Performance
Radio Local Area Network (HIPERLAN) Type 1, Functional
specification”, European Telecommunication Standard, ETS 300652,
ETSI (1996)
• Jochen Schiller, “Mobile Communications”, 2:nd Edition, Addison-
Wesley, 2003
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