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Wireless N and County Code mess with SL

It took me a while to find out what was causing my Wireless N connection problems using 10.5.8 Leopard, and now with Snow Leopard. It seems that somehow the Airport Card Country code (and therefore the supported channels and frequencies) changes with the associated MAC Address (or some other serial number that Apple can tell where the AP should be from) of the Connected Access Point. I know this because when my Airport is disconnected it shows me no Coutry Code. When I connect in my wi-fi college it shows me US country code, and at home (using a WRT610N), a different one that's unable to use wireless N frequencies. Am I the only one having this problem? I don't want to use Wireless G, and I have no idea how to fix this!

Here's what appears in my 17" mid-2009 MBP info:

PS: My WRT-610N is set to work with .N connections only, both 2.4 and 5GHz. So my MBP won't connect at home because the Country Code it sets doesn't support .N.

@ Home (WRT610N)

Software Versions:
Menu Extra: 6.0 (600.22)
configd plug-in: 6.0 (600.27)
System Profiler: 6.0 (600.9)
Network Preference: 6.0 (600.22)
AirPort Utility: 5.4.2 (542.23)
IO80211 Family: 3.0 (300.20)
Interfaces:
en1:
Card Type: AirPort Extreme (0x14E4, 0x8D)
Firmware Version: Broadcom BCM43xx 1.0 (5.10.91.19)
Locale: FCC
Country Code: ZW
Supported PHY Modes: 802.11 a/b/g
Supported Channels: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
Wake On Wireless: Supported
Status: Not Associated

@ Airport without any wi-fi connection

Software Versions:
Menu Extra: 6.0 (600.22)
configd plug-in: 6.0 (600.27)
System Profiler: 6.0 (600.9)
Network Preference: 6.0 (600.22)
AirPort Utility: 5.4.2 (542.23)
IO80211 Family: 3.0 (300.20)
Interfaces:
en1:
Card Type: AirPort Extreme (0x14E4, 0x8D)
Firmware Version: Broadcom BCM43xx 1.0 (5.10.91.19)
Locale: FCC
Country Code: X0
Supported PHY Modes: 802.11 a/b/g/n
Supported Channels: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 36, 40, 44, 48, 52, 56, 60, 64, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, 149, 153, 157, 161, 165
Wake On Wireless: Supported
Status: Off

@ College

Software Versions:
Menu Extra: 6.0 (600.22)
configd plug-in: 6.0 (600.27)
System Profiler: 6.0 (600.9)
Network Preference: 6.0 (600.22)
AirPort Utility: 5.4.2 (542.23)
IO80211 Family: 3.0 (300.20)
Interfaces:
en1:
Card Type: AirPort Extreme (0x14E4, 0x8D)
Firmware Version: Broadcom BCM43xx 1.0 (5.10.91.19)
Locale: FCC
Country Code: US
Supported PHY Modes: 802.11 a/b/g/n
Supported Channels: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 36, 40, 44, 48, 52, 56, 60, 64, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, 149, 153, 157, 161, 165
Wake On Wireless: Supported
Status: Connected
Current Network Information:
USPnet:
PHY Mode: 802.11g
BSSID: 0:5:9e:8c:b4:ed
Channel: 6
Network Type: Infrastructure
Security: None
Signal / Noise: -72 dBm / -89 dBm

Message was edited by: andre.mengatti

17" 2.88 Ghz MBP 5.2 500GB 5.4K Hitachi, Mac OS X (10.5.7)

Posted on Aug 31, 2009 10:59 AM

58 replies

Dogcow-Moof

Level 8

36,239 points

Oct 3, 2009 12:07 AM in response to andre.mengatti

The problem is if Apple implements a "use the country code of the router I'm associating with" approach, if they are associating with an illegal router, their devices are also then operating on illegal frequencies.

Note also that most other operating systems also implement "first 802.11d beacon wins" when it comes to country codes.

Dogcow-Moof

Level 8

36,239 points

Oct 3, 2009 12:25 AM in response to andre.mengatti

Here's the relevant portion of the spec:

9.9.1 Operation upon entering a regulatory domain

A STA that is enabled for operation across regulatory domains shall default to passive scanning when it has lost connectivity with its ESS. Passive scanning is performed using only the receive capabilities of the station and is, thus, compatible with regulatory requirements. The timeout for determining the loss of connectivity is system dependent and beyond the scope of this standard.

When a STA enters a regulatory domain, it shall passively scan to learn at least one valid channel, i.e., a channel upon which it detects IEEE Std 802.11 frames. The Beacon frame contains information on the country code, the maximum allowable transmit power, and the channels to be used for the regulatory domain. Optionally, the Beacon frame may also include, on a periodic basis, the regulatory information that would be returned in a Probe Response frame. Once the STA has acquired the information so that it is able to meet the transmit requirements of the regulatory domain, it shall transmit a Probe Request to an AP to gain the additional regulatory domain information contained in the Probe Response frame, unless the information was previously received in a Beacon fame. The STA then has sufficient information available to configure its PHY for operation in the regulatory domain.

http://standards.ieee.org/getieee802/download/802.11d-2001.pdf

There's nothing there about getting the information from the router you wish to associate with, just that once the STA has sufficient information to configure its PHY from passive listening it should do so.

Oct 3, 2009 10:09 AM in response to Dogcow-Moof

No, there isn't. That's the point. It *doesn't say the first beacon frame should set the router PHY*. It doesn't say what to do when multiple beacon frames are available. It's a *sui generis* situation, not defined by the standard.

You're saying that if it's chosen to use the country code from the associated router, people may misuse this feature to access ilegal frequencies.

Well, right now I'm using ZIMBABWE country code settings. And there's nothing I can do with my legally bought router and computer to solve this, because Apple's implementation of 802.11d should be as fuzzy and impartial as the standard itself in this matter? So I just have to accept that I'm forced to use wrong (and maybe even forbidden in my country) wi-fi frequencies because someone in my neighborhood has the wrong router?

I'm sorry, I don't see things as you do William. I'll go back to 10.5.7, and I'll definitely not keep my new MBP for a long time is this doens't get fixed.

MosziNet

Level 1

11 points

Oct 4, 2009 12:50 PM in response to andre.mengatti

Well, I don't have another ideea, but ... there is this script ... modified it a bit, it disabled / enables the radio until the PHY modes are correct .... Hope this helps temporarily ... 😟

#!/bin/bash

# This script will turn the AirPort on and off
# until the country code is different from "SY"
#
# author: Martin Bartos (f1lth@msn.com)
# modified: Szilveszter Molnar (mail@moszi.net)

if [[ $EUID -ne 0 ]]; then
echo " This script must be run as root" 1>&2
exit 1
fi

cont=1

while [[ $cont -ge 1 ]]; do
echo
log=`system_profiler SPAirPortDataType | grep "a/b/g" | cut -d ":" -f 2`

if [[ $log != " 802.11 a/b/g/n" ]]; then
echo $log
echo -n " Restarting AirPort [$cont] ... "
sudo networksetup -setairportpower en1 off
sleep 6
sudo networksetup -setairportpower en1 on
sleep 2
let "cont+=1"
echo " DONE"
else
echo $log
echo " Happy Networking 😉"
echo
cont=0
fi
done
exit 0

MosziNet

Level 1

11 points

Oct 5, 2009 2:17 AM in response to MosziNet

I have filed a bug report with this issue. Lets see what happens ...

Dogcow-Moof

Level 8

36,239 points

Oct 5, 2009 2:43 AM in response to MosziNet

For what it's worth, at present it appears Linux also uses the "first beacon wins" strategy, though there are utilities that allow you to manually change the country code.

Windows does appear to use the country code of the router you associate with, but don't quote me on that; MSDN is also a little fuzzy on the topic.

Oct 5, 2009 6:25 PM in response to Dogcow-Moof

How do I run this script?

I tried using script editor, I doesn't work (Syntax Error).

Tried running with "su" in terminal, doesn't work either....

MosziNet

Level 1

11 points

Oct 10, 2009 6:25 AM in response to andre.mengatti

Sorry mate, posting it again, this time i have uploaded the file to my server so the automatic formatting doesn't mess it up:
http://www.moszi.net/dev/download/AirportSwitcher.txt

download the text of the script
create a new file
paste the script into this file
open terminal
do a "chmod a+x yourfilename"
do a "sudo yourfilename"

also be sure to get as close to your router as you can, because this way it will find the broadcast signal faster

Oct 20, 2009 1:27 PM in response to MosziNet

sudo: AirportSwitcher.txt.sh: command not found

tried to change the file extension, and got the same error...

What am I doing wrong?

Oct 20, 2009 1:34 PM in response to andre.mengatti

Nevermind, I got it working.

After 4 reboots I got the correct country code.

That "solved" my problem... thanks a lot!

MosziNet

Level 1

11 points

Oct 20, 2009 2:41 PM in response to andre.mengatti

hm. i was wrong again 🙂
instead of doing a "sudo yourfilename" do a "sudo ./yourfilename" when you are in the same directory where your script is.

rebooting though is not necessary, just turn the ariport off-and-on-again several times until you see the correct code - or use this script 😉

putnik

Level 4

1,179 points

Oct 21, 2009 12:24 AM in response to Dogcow-Moof

I have found that making a new location in the network preferences for airport, and not using the default "automatic" option has stopped wifi disconnects.

Could it be that this gets over the beacon search locking onto a third party location?

MosziNet

Level 1

11 points

Oct 21, 2009 1:03 AM in response to putnik

Hi Putnik,

i wouldn't bet on this, since airport searches for a new beacons at every startup. This means even after you computer is woke up after a sleep ...

Dogcow-Moof

Level 8

36,239 points

Oct 21, 2009 7:32 AM in response to MosziNet

MosziNet wrote:
i wouldn't bet on this, since airport searches for a new beacons at every startup. This means even after you computer is woke up after a sleep ...

That's correct.

This is done as the Mac otherwise would not know if you had say, put it to sleep in one regulatory domain and had awakened it in another.

putnik

Level 4

1,179 points

Oct 21, 2009 9:13 AM in response to Dogcow-Moof

I am no expert, so please tell me, is making a new location in the airport preferences going to cause problems when I move around? Can you enlighten me as to why it (seems to have) cured a disconnection problem.

I did notice that I was said to be in Lisbon for a while and it took several attempts before I even got the option of Madrid where I actually live. This may relate to the large immigrant community living around here:)

Wireless N and County Code mess with SL