[PLUG] Why Laptop Cannot Find Wireless Networks

[Mike Connors]

>
> "my wireless network sniffer shows a strong signal (3-4 of 4 lights on)
> yet wicd-client cannot find a wireless
>
network for connection"

That "signal" could be another wifi client on a computer and not an Access
Point. It could be some other device in the same radio spectrum.

If your wireless network manager cannot see the RF signal from a wireless AP
and it's corresponding information necessary for a wifi client to connect to
it, ip connectivity is not the issue. You have to have radio (physical
layer) connectivity before you can get ip layer connectivity.

The only real test here is to use a low level wireless tool such as iw. If
when you run the command "iw wlan0 scan", you don't get results like below
there's a RF level communication problem between the radio in your wifi card
and the radio in the wireless AP.

iw wlan0 scan
BSS ac:81:12:e6:f9:d6 (on wlan0) -- associated
        TSF: 896764416400 usec (10d, 09:06:04)
        freq: 2412
        beacon interval: 100
        capability: ESS Privacy ShortSlotTime (0x0411)
        signal: -46.00 dBm
        last seen: 97 ms ago
        SSID: MOTOROLA-60169
        Supported rates: 1.0* 2.0* 5.5* 11.0* 18.0 24.0 36.0 54.0
        DS Parameter set: channel 1
        ERP: <no flags>
        RSN:     * Version: 1
                 * Group cipher: CCMP
                 * Pairwise ciphers: CCMP
                 * Authentication suites: PSK
                 * Capabilities: 16-PTKSA-RC (0x000c)
        Extended supported rates: 6.0 9.0 12.0 48.0
        HT capabilities:
                Capabilities: 0x187c
                        HT20
                        SM Power Save disabled
                        RX Greenfield
                        RX HT20 SGI
                        RX HT40 SGI
                        No RX STBC
                        Max AMSDU length: 3839 bytes
                        DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 1/2 usec (0x02)
                HT RX MCS rate indexes supported: 0-15
                HT TX MCS rate indexes are undefined
        WPS:     * Version: 1.0
                 * Manufacturer: Motorola
                 * Model: Motorola
                 * Device name: MotorolaAP
                 * Config methods: Display, PBC
        WMM:     * Parameter version 1
                 * u-APSD
                 * BE: CW 15-1023, AIFSN 3
                 * BK: CW 15-1023, AIFSN 7
                 * VI: CW 7-15, AIFSN 2, TXOP 3008 usec
                 * VO: acm CW 3-7, AIFSN 2, TXOP 1504 usec
BSS 00:1c:10:74:74:ff (on wlan0)
        TSF: 3072096318715 usec (35d, 13:21:36)
        freq: 2462
        beacon interval: 100
        capability: ESS Privacy ShortSlotTime (0x0411)
        signal: -70.00 dBm
        last seen: 3639 ms ago
        SSID: HAL2001
        Supported rates: 1.0* 2.0* 5.5* 11.0* 18.0 24.0 36.0 54.0
        DS Parameter set: channel 11
        ERP: <no flags>
        Extended supported rates: 6.0 9.0 12.0 48.0
BSS e4:e0:c5:00:0e:eb (on wlan0)
        TSF: 1110937987 usec (0d, 00:18:30)
        freq: 2462
        beacon interval: 100
        capability: ESS Privacy SpectrumMgmt ShortSlotTime (0x0511)
        signal: -75.00 dBm
        last seen: 3632 ms ago
        SSID: SEC_LinkShare_aa5faf
        Supported rates: 1.0* 2.0* 5.5* 11.0* 18.0 24.0 36.0 54.0
        DS Parameter set: channel 11
        Country: US (in/outdoor), data: 01 0b 1e
        Power constraint: 0 dB
        ERP: <no flags>
        RSN:     * Version: 1
                 * Group cipher: CCMP
                 * Pairwise ciphers: CCMP
                 * Authentication suites: PSK
                 * Capabilities: 16-PTKSA-RC (0x000c)
        Extended supported rates: 6.0 9.0 12.0 48.0
        HT capabilities:
                Capabilities: 0x186c
                        HT20
                        SM Power Save disabled
                        RX HT20 SGI
                        RX HT40 SGI
                        No RX STBC
                        Max AMSDU length: 3839 bytes
                        DSSS/CCK HT40
                Maximum RX AMPDU length 32767 bytes (exponent: 0x002)
                Minimum RX AMPDU time spacing: 1/2 usec (0x02)
                HT RX MCS rate indexes supported: 0-15
                HT TX MCS rate indexes are undefined
        WPS:     * Version: 1.0
        WMM:     * Parameter version 1
                 * u-APSD
                 * BE: CW 15-1023, AIFSN 3
                 * BK: CW 15-1023, AIFSN 7
                 * VI: CW 7-15, AIFSN 2, TXOP 3008 usec
                 * VO: CW 3-7, AIFSN 2, TXOP 1504 usec