Sign in

Getting a smarter security personnel everyday !!

2.4GHz band

The 2.4GHz band frequency ranges from 2.4GHz-2.4835GHz and is used by 802.11a, 802.11b, 802.11g. The band is divided into 14 fixed-frequency channels, each being 20MHz wide.

The gap between adjacent channels is 5MHz wide, and these channels have many overlaps. Thus, only 3 channels can be active at the same time. You can find non-overlapping channels like 1, 6, and 11. The 2.4GHz band is very crowded as this range is also used by devices like baby monitors, cordless phones, microwave ovens, Bluetooth, etc... Not many channels are available for use. And is susceptible to more interference.

But the advantage…


IEEE standards refer to the set of layer 1 and layer 2 specifications for a WLAN.

The first version was released in 1997, and 6 different versions have been brought since then. — 1) 802.11a, 2) 802.11b, 3) 802.11g, 4) 802.11n, 5) 802.11ac, and 6) 802.11ad

Collectively these standards are known as wireless fidelity (WI-FI).

All these standards are similar in 3 aspects:

  • They use half-duplex signaling. That means a device can either transmit or receive, but not perform both simultaneously.
  • They all use 2.4 GHz and 5 GHz frequency bands.
  • Layer 2 medium access control method is called CSMA/CA (carrier sense multiple access with collision avoidance).

MIMO — Multiple Input Multiple Output


What is Association?

In wireless networks, association means wireless devices register with an AP/router to get access to the network. Association happens only in infrastructure mode, not in Ad Hoc mode.

To establish this association, a wireless device uses scanning methods to find an AP/router.

ACTIVE SCANNING

A wireless device broadcasts a probe signal to each channel in its frequency range and waits for an AP to respond. So the client initiates the search method.

  • Step 1 — The device continually sends the signal searching for an AP.
  • Step 2 — Both the APs respond by sending their SSIDs and some other information to the…

WLAN is a network in which devices are communicating wirelessly with each other in a defined area.

The WLAN is ultimately connected to a wired network.

WAP

A Wireless access point or simply called an access point accepts a wireless signal from multiple devices and retransmits them to the rest of the network. At-home settings, a WAP may be capable of routing therefore may also be called a wireless router or wireless gateway. But in business settings, AP and routers are separate devices. …


WLAN has 2 architecture modes: Ad Hoc, Infrastructure

AD HOC MODE

Ad Hoc mode is a decentralized type of network. Wireless devices communicate with each other directly instead of using an access point. So Ad Hoc mode is peer-to-peer. It doesn't need a complex setup. It is quick and cheap.

As more users get connected to the network this type of network shows deterioration in performance. And security is also not that. Use it only if your devices trust each other.

INFRASTRUCTURE MODE

This mode is more common with companies and organizations. This is a centralized wireless network where devices communicate via access points and…


All devices in an IPv6 network are required to have a link-local unicast address, starting with FE80::/64. The device can generate the other 64bit half by the EUI-64 method or by generating random value.

But, before a device starts using the self-generating address, it needs to check if the address is being used already by any other device. This is achieved through a process called Duplicate Address Detection (DAD).

DAD leverages Neighbor Solicitation and Neighbor Advertisement messages.

Suppose, C wants to join the local network. C generates a tentative unicast link-local address using EUI-64 based on its MAC address.

  • C…

In TCP/IP, we use both IP and MAC addresses.

MAC Address

  • MAC address (physical address) is a globally unique physical ID of your device.
  • It is useful and efficient for local communication only. For example — If you want to talk to your classmate sitting next to you, his mail address info is unnecessary for you.
  • Since IP addresses change, they only reveal where you are and don’t reveal who you are. MAC addresses do reveal your identity but not your location.
  • MAC address is burnt into the NIC (Network Interface Card). If your NIC gets damaged all the connections will be lost.

IP Address

  • They can group and organize different networks.
  • It is like a home address.
  • It is flexible and allows a device to be mobile between different networks.
  • Indicates where you are but not who you are.

Dynamic Host Configuration Protocol version 6 is similar to DHCP in IPv4 and its function is to configure IPv6 clients with the information required by an IPv6 device to operate on an IPv6 local network.

In IPv6 a device can get addressing information in 3 ways:

  • Stateless address autoconfiguration (SLAAC)
  • Stateful address autoconfiguration
  • Manual (Too complicated and uncommon in usage)

SLAAC

SLAAC refers to the ability of the host’s ability to get addressing information by itself.

  • A host can also get other information like DNS address through NDP, or by DHCPv6
  • Stateless means that a server doesn’t maintain information like IP…

Similar to IPv4’s ARP(address resolution protocol), to get link-layer host addresses or connection information of available routers.

NDP operates on the link layer of the OSI model and has the following functions:

  • Performing stateless auto-configuration of addresses for an interface.

Stateless auto-configuration allows a device to connect to the internet without a DHCP server.

  • Address resolution.

Mapping from IP address to a physical address.

  • Neighbour Unreachability Detection.

Determine that a neighbor is no longer reachable on the link.

  • Duplicate Address Detection.

Nodes need to check whether an IP address is already in use.

NDP and ICMPv6

NDP uses Internet Control Message Protocol version…


The IPv6 global unicast address is similar to IPv4 public IP address. It is used when a host wants to use the internet.

2001:1234:ABCD:5678:0221:2FFF:FEB5:6E10

This example address shows 8 groups of 16-bit hexadecimal numbers, separated by colons, 128 bit long altogether. Starting with 2001, a global unicast address consists of 3 sections. 2001:1234:ABCD is called a global routing prefix (first 48 bits). 5678 is called the subnet ID (next 16 bits). The third part, 0221:2FFF:FEB5:6E10 is called the interface ID (last 64 bits), which is the host part.

Obtaining the address

This is a 2-step process. The global routing prefix and the subnet…

Geeky much!

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store