News items for tag wifi - Koos van den Hout

2014-09-05 Upgrade of the wireless network
I am used to new access-points showing up at home which make us change the channel from time to time, but after getting hickups in youtube video on a tablet for the second time in a week I decided it was time to go dual-band and higher speeds. Good advice was to look at the TP-Link TL-WDR4300 which is dual-radio dual-band with 802.11n support with mimo. The advertised 750 megabit is when you add 802.11n at 300 megabit on 2.4 GHz and 802.11n at 450 megabit on 5 GHz. I'm not setting up extra wide channels on 2.4 GHz since it is busy enough, so I won't be seeing 300 megabit on 2.4 GHz anyway. I set up the network SSID and security on 5 GHz exactly the same as on 2.4 GHz so devices can switch automatically.

Week of wifi signal statistics showing access-point upgrade The weather station computer in the shed also measures wifi signal strength, the difference is clear so the TP-Link also has a stronger signal on 2.4 GHz. The wireless card in the weather station computer can do 5 GHz, but its antenna is tuned for 2.4 GHz and there are multiple walls between the access-point and that antenna.

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2014-08-20 Wireless regulatory domain now showing DFS master region
An interesting new message showing for the wireless config:
[2668364.843138] cfg80211: Calling CRDA to update world regulatory domain
[2668365.630995] cfg80211: World regulatory domain updated:
[2668365.631018] cfg80211:  DFS Master region: unset
[2668365.631029] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[2668365.631046] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[2668365.631062] cfg80211:   (2457000 KHz - 2482000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[2668365.631078] cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (N/A, 2000 mBm)
[2668365.631093] cfg80211:   (5170000 KHz - 5250000 KHz @ 80000 KHz), (N/A, 2000 mBm)
[2668365.631109] cfg80211:   (5735000 KHz - 5835000 KHz @ 80000 KHz), (N/A, 2000 mBm)
[2668365.631124] cfg80211:   (57240000 KHz - 63720000 KHz @ 2160000 KHz), (N/A, 0 mBm)
[2668365.632073] cfg80211: Calling CRDA for country: NL
[2668365.661681] cfg80211: Regulatory domain changed to country: NL
[2668365.661703] cfg80211:  DFS Master region: unset
[2668365.661715] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[2668365.661731] cfg80211:   (2402000 KHz - 2482000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[2668365.661747] cfg80211:   (5170000 KHz - 5330000 KHz @ 80000 KHz), (N/A, 2000 mBm)
[2668365.661763] cfg80211:   (5490000 KHz - 5710000 KHz @ 80000 KHz), (N/A, 2700 mBm)
[2668365.661778] cfg80211:   (57240000 KHz - 65880000 KHz @ 2160000 KHz), (N/A, 4000 mBm)
The message about DFS Master region is new to me, compared to the crda messages I saw last february.

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2014-02-26 Linux wireless regulatory domain information
I noticed in the logs of the weather station computer ritchie:
[770336.506717] cfg80211: Calling CRDA to update world regulatory domain
[770336.906545] cfg80211: World regulatory domain updated:
[770336.906567] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[770336.906585] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[770336.906602] cfg80211:   (2457000 KHz - 2482000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[770336.906619] cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
[770336.906635] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[770336.906652] cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
But I'm in a specific country (the Netherlands) although the access-point is old enough to not transmit the regulatory domain information. I found out I can update the default in the client using:
root@ritchie:~# iw reg get
country 00: DFS-UNSET
        (2402 - 2472 @ 40), (3, 20)
        (2457 - 2482 @ 40), (3, 20), NO-IR
        (2474 - 2494 @ 20), (3, 20), NO-OFDM, NO-IR
        (5170 - 5250 @ 40), (3, 20), NO-IR
        (5735 - 5835 @ 40), (3, 20), NO-IR
root@ritchie:~# iw reg set NL
root@ritchie:~# iw reg get
country NL: DFS-UNSET
        (2402 - 2482 @ 40), (N/A, 20)
        (5170 - 5250 @ 40), (N/A, 20), NO-OUTDOOR
        (5250 - 5330 @ 40), (N/A, 20), NO-OUTDOOR, DFS
        (5490 - 5710 @ 40), (N/A, 27), DFS
        (57240 - 65880 @ 2160), (N/A, 40), NO-OUTDOOR
This changes maximum power, bandwidth and frequency ranges. And indeed in dmesg:
[770977.623611] cfg80211: Calling CRDA for country: NL
[770977.715887] cfg80211: Regulatory domain changed to country: NL
[770977.715909] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[770977.715926] cfg80211:   (2402000 KHz - 2482000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[770977.715941] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[770977.715957] cfg80211:   (5250000 KHz - 5330000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[770977.715972] cfg80211:   (5490000 KHz - 5710000 KHz @ 40000 KHz), (N/A, 2700 mBm)
[770977.715988] cfg80211:   (57240000 KHz - 65880000 KHz @ 2160000 KHz), (N/A, 4000 mBm)
Now I wonder about the flags... NO-IR = no initiating radiation the device may not transmit on a frequency until it has received beacons on the frequency. DFS = Dynamic Frequency Selection which is mainly avoiding collision on the 5 GHz wireless band with weather radars.

More information about this subject at Regulatory - Linux Wireless.

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2013-12-16 (#)
Ik vroeg me recent af wat het aanbod is in access-points voor thuis met dual-radio support, dus tegelijkertijd actief op 2.4 GHz en 5 GHz. Op de 5 GHz band is minder storing maar niet alle apparaten die wifi gebruiken ondersteunen 5 GHz. En 802.11n op 2.4 GHz doen is volgens mij asociaal omdat je dan helemaal andere netwerken in de buurt stoort.

Toevallig blijkt het agentschap telecom het met me eens te zijn: Met een combi-router ben je goed voorbereid op de Wi-Fi van de toekomst - Agentschap Telecom.

Dus liefst heb ik een access-point met dual-radio, 802.11n ondersteuning alleen op 5 GHz, WPA2 en niet te veel stroomgebruik. Het lijkt soms dat 2 access-points met verschillende settings wel eens goedkoper in aanschaf kunnen zijn dan eentje met al deze opties, alleen dan vast in stroomgebruik niet.

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2013-10-29 (#)
Gelijk na het bijwerken naar UTF-8 codering liep ik weer eens door het document Draadloos netwerk uitleg en installatie. Sommige links waren niet meer geldig en ik kon nog wat tekst verbeteren.

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2012-09-06 (#)
Sophos the security company went warbiking in central London and found very high numbers of wireless networks, with parts still without any security or with bad wireless security. All explained with a nice youtube video which presents the results in a format even your neighbour who still relies on WEP can understand.

The Sophos warbiking project.

Found via Warbiking: WiFi hacken op de fiets - security.nl although I would avoid using the term 'hacking' for purely passive measurements.

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2012-01-06 (#)
A practical demo of the latest attack on WiFi security: Hands-on: hacking WiFi Protected Setup with Reaver - Ars Technica shows that it is quite easy to attack WiFi access-points which use WiFi Protected Setup (WPS). The idea behind WPS is that good WPA2 keys are difficult to remember and difficult to reliably copy from the access-point to the client system. WPS uses a PIN hard-coded in the access-point and a client which understands WPS can access the WPA2 key when it has the WPS pin.

But a vulnerability in the WPS system allows malicious clients to find the WPS pin (which cannot be changed..) which allows access to the current WPA2 key. So even if you change the WPA2 key, the WPS pin will still allow access to it.

WiFi security seems to be a constant arms race. And keeping the balance between security and accessibility is also important.

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2011-05-31 (#)
Don't mix christmas lights and wifi, according to What can get in Wi-Fi's way? - PC Pro:
Every holiday season, ISPs receive a spike in complaints that internet connections aren’t working. The culprit: that festive, sparkly, lit-up tree in the living room.

TalkTalk said Christmas tree lighting and other household lights can reduce Wi-Fi performance by 25%, and interference is at its worst when the lights are blinking.
Via What's Killing Your Wi-Fi? - Slashdot

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2011-03-22 (#)
The UU has changed certain settings of the Eduroam wireless network. And this change causes a problem with my Nokia E71. The change to the network includes a change in the certificate which has a different root certificate. I tried installing the AddTrust External CA Root certificate in the phone. It took me a while to find what the correct form of a certificate is: it has to be a DER format certificate and mime-type application/x-x509-ca-cert. To convert the certificate from the usual pem form I had to use:
openssl x509 -in AddTrust_External_CA_Root.pem -outform der -out AddTrust_External_CA_Root.crt
And download that .crt into the phone using the system browser. But even when I select that certificate for verifying the Eduroam network it fails at the moment.
Update 2011-03-23: Support had one look at the phone and decided to update the firmware first before trying to get eduroam running.
Update 2011-03-25: Updated firmware now gives me a working connection.

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