Someone's Second 🧠

    Routers

    Routers

    Intro

    • WiFi -> Wireless Fidelity

    Notes

    • Always mention it as Access Points not a Wifi router

    Two types of Access points

    Home / Personal

    • Arris
    • Tplink
    • Netgear

    Enterprise

    • Cisco
    • Rukus
    • Extreme
    • Aruba
    • CMBian

    Network Testing

    Project Management

    History

    • We moved from Ethernet -> Wifi
    • Move around - seamless connectivity
    • Security aspect - wifi sniffing - catching the packets.

    router_security

    Terminologies

    SSID

    The name of the AP Identifier.

    2.4 Ghz

    • Non overlapping channels
    • What channels AP shouldn't be using
    • What DFS channels are using
    • 20 mhz how many channels:?
    • In 40 mhz how many channels
    • 11 channels I believe in 2.4ghz
    • 1 , 6 and 11 are loosely coupled with least interference.
    • Better coverage
    • Penetrates better through solid files
    • It is legacy and more optimized overall.
    • Enterprise AP connected Wifi routers 2.4 ghz is more suitable.

    5 Ghz

    • Lower coverage
    • Faster transfer rates
    • Can penetrate lesser
    • Suited for 4K or higher bit rate content.
    • Newer technology

    Wifi 6 ax

    Wifi 6E

    Wifi 7

    6 hz

    RF

    80 11

    Radio Patterns

    • two or three patterns
    • 22 mhz channel range usual range.
    • Auto setting to select specific channels most of the time on router admin page.

    Exempted Frequencies

    • Also certain radio frequencies are always restricted for Federal for aviation and other security stuff.

    Site Surveys

    • How the AP are deployed
    • Signal strength - Heat Map
    • Channels in the picture - picking the right auto channel.

    Collision Detection / Avoidance

    Radio Frequency Isolation

    • RF Boxes

      • Antennas from one box to another chamber box. For isolated tests

    • RF Chamber

      • Laptop can take control of doing speed tests, channels to access outside the chamber
      • External AP access, without being in the chamber. Security, throughput, channel width
      • Present onsite in a lab for testing.

    • Screen rooms

    • Brands

      • Ramsey shield box RF shield box.

    Debug

    • Verbose Wifi SSID logging
    • Turn on verbose logging through Android system settings.
    • AP would show little bit slower because it may not have updated reactive web UI.

    Beacons

    • Listening to beacons is part of passive scanning

    Timeline

    • Wifi client -> Wifi AP
      Active Scanning

    Authentication handshake

    • Probe request <-> Ack
    • Authentication Request <-> Ack
    • Association Request <-> Ack

    DHCP

    Difference

    • Active vs Passive Scanning

    Switch

    Interview

    • Diff between active and passive scanning with examples