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content/notes/09-wireless-networking.md

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+---
+title: "09-wireless-networking"
+tags: 
+- lecture
+- cosc301
+---
+
+IEEE 802 Standards 
+- 802.1: Bridging and Management, e.g. 802.1X 
+- 802.3: Ethernet 
+- 802.11: Wireless (WiFi) 
+	- 802.11b, 802.11a, .11d, .11g, …, .11aj, .11ay 
+- 802.16 Broadband Wireless MAN (WiMAX) 
+- 802.15.4: Zigbee, wireless sensor networks 
+- 802.15.1: bluetooth, 802.15.6: WBAN 
+- http://standards.ieee.org/getieee802/
+
+802.11 Family 
+- 802.11b 
+	- 11Mbps, 2.4GHz, Kick-started Wi-Fi technology, ~30m indoors. 
+- 802.11a 
+	- 54Mbps, 5GHz, technically superior to 11g, gradually common. 
+- 802.11g 
+	- 54Mbps, 2.4GHz, still very common. Compatible with 11b. 
+- 802.11n 
+	- 540Mbps (typ. 200Mbps), 2.4+5GHz, current choice 
+	- Max speed hard to determine, ~50m indoor, MIMO 
+	- Supports a/b/g or ‘Greenfield’ (exclusive). 
+	- Also supports extensions for priority, multimedia 
+- 802.11aj -- 15Gbps, mmWave 
+- 802.11ay -- 20Gbps, mmWave
+
+Operation Modes of 802.11 
+- Independent or ad-hoc mode 
+	- Nodes in an ad-hoc network communicate without any need for network infrastructure such as an AP, or network level services such as DHCP, DNS 
+	- ZeroConf protocols to manage IP addresses etc. 
+- Infrastructure or managed mode 
+	- Requires an access point (AP) to function 
+	- Higher network layers such as data link and IP are configured using the same methods as any wired Ethernet. Most commonly DHCP is used 
+	- Further security measures may be employed to manage security risks associated with wireless
+
+Ad Hoc mode
+![](https://i.imgur.com/LwTjKdU.png)
+> [!INFO]
+
+Infrastructure mode
+![](https://i.imgur.com/GuhlwVA.png)
+> [!INFO]
+
+
+Basic terminology 
+- AP: Access Point 
+- STA: Station/devices 
+- BSS: Basic Service Set 
+	- A group of stations that communicate with each other via an access point. 
+- ESS: Extended Service Set 
+	- Multiple BSSs can be linked using a distribution system to create an Extended Service Set 
+- SSID: Service Set Identifier 
+	- The MAC address of an AP 
+- ESSID: Extended Service Set Identifier 
+	- The name of the network
+
+Wireless Distribution System (WDS) 
+- Backbone of multiple APs, and the inter-AP communication. Usually Ethernet, may be wireless. 
+- 802.11F defines the Inter Access-Point Protocol (IAPP)
+
+Signal Strength 
+- Signal Level: Strength of the received signal 
+- Noise Level: Strength of the noise 
+- Link Quality: Signal to Noise Ratio (SNR) 
+- Transmit Power: How loud we speak 
+- Receive Sensitivity: How well we can hear 
+- Decibel: 10*log10(P/P0), which shows the ratio of power of one signal over another.
+
+Finding a Network 
+- Passive scanning listens for AP beacons 
+	- Listens on each channel for a certain dwell time 
+	- Won’t detect closed/hidden networks 
+- Active scanning sends Probe Requests 
+	- On each channel 
+	- Requests a particular ESSID or “any” 
+	- Produces a scan report with discovered ESSIDs
+
+Security of WiFi 
+- MAC Filter List 
+	- Not a security protocol 
+	- Access Control by (changeable) MAC address 
+	- ACLs can be stored centrally using RADIUS 
+- WEP (Wired Equivalent Privacy) 
+	- Minimal protection 
+	- Not secure due to short key length 
+	- Pre-Shared Key (PSK)
+
+WPA 
+- Wi-Fi Protected Access 
+	- Subset of 802.11i that was released when WEP flaws became a barrier to adoption 
+- WPA Personal 
+	- WEP with short-lived changing keys 
+	- Temporal Key Integrity Protocol (TKIP) 
+	- Different key per user/session/packet 
+	- Performance cost if not done in hardware
+
+WPA Enterprise 
+- WPA Enterprise 
+	- 802.1X for user authentication 
+		- “Port” based authentication framework 
+		- Extensible Authentication Protocol (EAP) 
+	- Requires RADIUS backend 
+- 802.11i—WiFi Alliance calls it WPA2 
+	- Advanced Encryption Standard (AES) cryptography
+
+> [!QUESTION] what is RADIUS backend
+
+Security Issues 
+- Bandwidth stealing 
+	- You are responsible for their actions 
+- Access to wired network 
+	- and other wireless nodes 
+- ARP Poisoning 
+	- Man-in-the-middle attacks 
+- AP Spoofing
+
+> [!INFO]

content/notes/cosc-301.md

@@ -34,4 +34,8 @@ https://www.cs.otago.ac.nz/cosc301/schedule.php
 - [x] [[05-filesystems]]
 - [x] [[06-network-system-administration]]
 - [x] [[07-system-installation]]
+- [ ] [[08-post-installation]]
+- [ ] [[09-wireless-networking]]
+
+
 # Info