Pierow's Prattle » Wireless Networking

WiFi Regulatory Compliance – And How To Fix It

pierow — Thu, 02 Jun 2011 06:02:26 +0000

Wicher posted on Smörgåsbord about an interesting problem. His Atheros card was set to use the US regulatory domain even though he was in The Netherlands. This limited his ability to use wireless channels 12 & 13 which are allowed in Europe but not in the US. “iw reg set NL” did not resolve the problem (read the article for an in depth explanation of why) so he found a work-around. It seems that the crda (Central Regulatory Domain Agent) application as compiled under OpenWRT does not require a digital signature – allowing the accompanying database to be modified. With the newly updated crda database, he was able to access all 14 available channels. (Though admittedly, channel 14 is not authorized for use in Europe)

To quote his post:

regdbdump /usr/lib64/crda/regulatory.bin gives me an editable version of the database. I didn’t feel like limiting myself, so I replaced this:

country 00:
	(2402.000 - 2472.000 @ 40.000), (3.00, 20.00)
	(2457.000 - 2482.000 @ 20.000), (3.00, 20.00), PASSIVE-SCAN, NO-IBSS
	(2474.000 - 2494.000 @ 20.000), (3.00, 20.00), NO-OFDM, PASSIVE-SCAN, NO-IBSS
	(5170.000 - 5250.000 @ 40.000), (3.00, 20.00), PASSIVE-SCAN, NO-IBSS
	(5735.000 - 5835.000 @ 40.000), (3.00, 20.00), PASSIVE-SCAN, NO-IBSS
 
country US:
	(2402.000 - 2472.000 @ 40.000), (3.00, 27.00)
	(5170.000 - 5250.000 @ 40.000), (3.00, 17.00)
	(5250.000 - 5330.000 @ 40.000), (3.00, 20.00), DFS
	(5490.000 - 5600.000 @ 40.000), (3.00, 20.00), DFS
	(5650.000 - 5710.000 @ 40.000), (3.00, 20.00), DFS
	(5735.000 - 5835.000 @ 40.000), (3.00, 30.00)

with this:

country 00:
  (2402.000 - 2494.000 @ 40.000), (N/A, 30.00)
  (4910.000 - 5835.000 @ 40.000), (N/A, 30.00)
 
country US:
  (2402.000 - 2494.000 @ 40.000), (N/A, 30.00)
  (4910.000 - 5835.000 @ 40.000), (N/A, 30.00)

and then I converted the database to its binary form with db2bin.py which one can find in the wireless-regdb source code releases. Copied the new database over to my OpenWRT machine, restarted it, dmesg, presto:

cfg80211: Calling CRDA to update world regulatory domain
cfg80211: World regulatory domain updated:
    (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
    (2402000 KHz - 2494000 KHz @ 40000 KHz), (N/A, 3000 mBm)
    (4910000 KHz - 5835000 KHz @ 40000 KHz), (N/A, 3000 mBm)
ath: EEPROM regdomain: 0x0
ath: EEPROM indicates default country code should be used
ath: doing EEPROM country->regdmn map search
ath: country maps to regdmn code: 0x3a
ath: Country alpha2 being used: US
ath: Regpair used: 0x3a
phy0: Selected rate control algorithm 'ath9k_rate_control'
phy0: Atheros AR9100 MAC/BB Rev:0 AR2133 RF Rev:a2 mem=0xb80c0000, irq=2
cfg80211: Calling CRDA for country: US
cfg80211: Regulatory domain changed to country: US
    (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
    (2402000 KHz - 2494000 KHz @ 40000 KHz), (N/A, 3000 mBm)
    (4910000 KHz - 5835000 KHz @ 40000 KHz), (N/A, 3000 mBm)

root@t33t:~# iwlist wlan0 channel
wlan0     14 channels in total; available frequencies :
          Channel 01 : 2.412 GHz
          Channel 02 : 2.417 GHz
          Channel 03 : 2.422 GHz
          Channel 04 : 2.427 GHz
          Channel 05 : 2.432 GHz
          Channel 06 : 2.437 GHz
          Channel 07 : 2.442 GHz
          Channel 08 : 2.447 GHz
          Channel 09 : 2.452 GHz
          Channel 10 : 2.457 GHz
          Channel 11 : 2.462 GHz
          Channel 12 : 2.467 GHz
          Channel 13 : 2.472 GHz
          Channel 14 : 2.484 GHz
          Current Frequency=2.452 GHz (Channel 9)

In short:

Download binary database from router
Get the tools mentioned in the article
Use the tools to dump the database to text format
Edit the database
Use the tools to convert the database back to binary format
Upload DB to router

[Read the full article - WiFi regulatory compliance, and how to fix it]

SailMail Provides Email Communication While at Sea

pierow — Wed, 02 Mar 2011 02:59:01 +0000

SailMail is radio based e-mail system designed for yacht owners to facilitate email communication while at sea. SailMail’s utilizes its own world-wide network of SSB-Pactor radio stations, satellite (Iridium, Inmarsat, Globalstar, Thuraya) or any other method of internet access. Much of its underlying technology is built upon the Winlink software used by amateur radio enthusiasts but SailMail only requires a marine radio license, not an amateur radio license.

The SailMail system implements an efficient email transfer protocol that is optimized for use over communications systems that have limited bandwidth and high latency. Satellite communications systems and SSB-Pactor terrestrial radio communications systems both have these characteristics. The SailMail email system’s custom protocol substantially reduces the number of link-turn-arounds and implements compression, virus filtering, spam filtering, and attachment filtering. The combination of the protocol, compression, and filtering dramatically improves communications efficiency.

[SailMail Site]

Cracking WPA using Video Cards with CUDA Support

pierow — Thu, 06 Aug 2009 20:16:57 +0000

I-Hacked has an article describing the process for cracking Wi-Fi Protected Access (WPA and WPA2) encryption using the additional processing power of video cards with CUDA support.

[Link]

The Mesh Potato – Mesh Routed VoIP Networking for Developing Communities

pierow — Thu, 19 Mar 2009 15:19:02 +0000

The Mesh Potato project hopes to build an 802.11bg mesh router with a single FXS port. It is designed to provide telephony via VOIP while simultaneously facilitating a mesh cloud. It is an open hardware and open software design. It will run off a nominal 12VDC, from either a mains supply or solar PV system, and be priced in the range of currently available Wifi routers (sub US$100).

The target application is mesh routed VOIP networks, in particular (but not limited to) developing communities. An analog phone connects to the potato via the FXS port. When you make a call you potato talks to the potato down the street which talks to the next potato, and eventually to the destination. The mesh network can be augmented via backbone links and connected to the rest of the world via VOIP gateways.

[More]

1000 mW MINI-PCI 802.11 Adaptor

pierow — Tue, 17 Mar 2009 15:17:00 +0000

Back in July, 2008, Freespace Systems announced the availability of their high performance 802.11 miniPCI radio. The Valemount KXS30SG is the first full 1 Watt miniPCI radio module available worldwide.

The card is Atheros AR5414 based and is supported by a wide number of open-source & commercial operating systems (Including StarOS, Linux MadWifi, MikroTik, & Ikarus. It also comes with both MMCX (micro-miniature coaxial) and Hirose U.FL antenna connectors.

[Pasadena Networks has the cards for $69] [Datasheet for the KXS30SG]

Ubiquiti Networks’ Bullet Outdoor Access Point

pierow — Wed, 11 Mar 2009 11:03:18 +0000

Ubiquiti Networks Bullet

The Ubiquiti Networks Bullet outdoor 802.11 access point is scheduled for release this month has been released. The low-power (100 mW) version is $40 and the 1,000 mW (1 watt) version is $90. (No, that’s not a typo) It’s powered via PoE and connects directly to the antenna so the only connection required is CAT-5. The operating temp is inline with an outdoor application -20C to +70C (-4F to 158F) and it runs AirOS. This could be the Holy Grail for implementing low-cost mesh wireless data networks.

UPDATE: Pasadena Networks has the Ubiquiti Bullet in stock!

[Datasheet] [Resellers] [Bullet Forum]

NEMA Enclosures for Outdoor 802.11 Access Points

pierow — Mon, 09 Mar 2009 13:23:10 +0000

Using NEMA enclosures to house and protect wireless gear in an outdoor environment is nothing new but they tend to look like someone gutted their Linksys WRT54G and crammed the guts into a plastic box.

L-CON has some really elaborate examples showing multiple access points, surge protection, amplifiers, band pass filters, etc all in a neat, logical layout. Impressive!

[HyperLink Brand NEMA Enclosure Configuration Examples]

Creating a Ship to Shore 802.11 Link

pierow — Mon, 09 Mar 2009 07:09:49 +0000

Tony’s Cafe has a really interesting article on using amplifiers along with a combination of omnidirectional and yagi antennas to create a ship-to-shore 802.11 wireless link. Of particular interest is the use of Hyperlink amps and the calculations to compute signal loss due to connectors, cable length, etc.

[Understanding 802.11 2.4GHz Amplifiers and Antennas (and Creating a Ship to Shore Link)]