WLAN – nerdia.net

iPhone, iPad or Mac computers unable to connect to wifi network

September 19, 2018/0 Comments/in Apple Mac OS X, Mobile, Wifi/by Stefan Helander

The Apple products, iPhone, iPad and Mac computers sometimes has problems when connecting to a wifi network where other devices have no problems. The problem seems to be in the encryption used.

Make sure the router doesn’t have WPA/WPA2 mixed mode enabled, i.e. set it to WPA2 only. If encryption is configurable, use AES (not TKIP or TKIP/AES).

You can also read more about Apple recommendet wifi router settings here: https://support.apple.com/en-us/HT202068

Improving wifi in a crowded wifi environment

May 27, 2014/0 Comments/in Hardware, Wifi/by Stefan Helander

This is a litle trick I use when I travel and hook up to a wifi network in a crowded wifi environment. Sometimes the network performance over wifi is really bad and the problem is that it can be caused by heavy traffic (like file sharing) on another wifi network sharing the same channel as yours. I have experienced this especially when travelling to big cities like Paris, Amsterdam and so on. First of all, it is recommended that you disable 802.11n wifi mode which works terribly bad in crowded environments. See this article for Windows and this for Linux (Ubuntu).

Crowded wifi environment (Wifi Analyzer for Android)

The problem with the wifi technology is that networks in the neighbourhood is sharing the same channels. In the 2,4 GHz band there are only 11-14 channels availible (depending on your region) and those channels overlap. That means if your network is on channel 1 you will get interference with traffic on channels 1, 2 and 3. Another problem with wifi is that is has no means of evenly dividing the capacity (like timeslots), so it is kind “the one shouting highest gets the most bandwidth”. And when someone already is using a lot of bandwidth (like file sharing) it is very hard for other users to obtain a part of the bandwidth. Even if it is the neighbours wifi which you can’t access but it shares the wifi channel.

A countermeasure to improve the situation is to constantly use some bandwidth forcing the heavy users to pull back a bit. Before transmitting, each node in the network listens in the air if the channel is free, so by using a little bit of bandwidth even if idle you don’t give the other node the same possibilty to hog the entire capacity.

First of all, find out the IP address of your local network default gateway. In WIndows you run a command prompt (cmd) and type the command ipconfig. In Linux you can use netstat -rn.

To constantly use up a small portion of the bandwidth I use the ping comand. Ping normally sends very small packets (56 bytes), but to get this to work we need a bit larger packets (but not to large, then we will hog the entire capacity). 1024 bytes is good.

In Windows you run the command (replace 192.168.0.1 with the IP-address of your local network which you found out above):

ping -t -l 1024 192.168.0.1

and in Linux you run:

ping -s 1024 192.168.0.1

ping with 1024 bytes

Voila! Now my wifi connection gets a lot more stable because I force the other wifi nodes to pull pack a bit since I constantly make them aware of my presence.

Disable 802.11n on Compaq 6910p with iwl4965 in Ubuntu

April 24, 2014/1 Comment/in Hardware, Linux/FreeBSD, Wifi/by Stefan Helander

I’ve found out that the 802.11n high speed wifi / wlan mode (300 Mbps theoretically) tends to cause more harm than good, i.e. the performance in many, especially crowded, wifi environments will be really poor and it is a better option to turn it off.

My Compaq 6910p laptop comes with an Intel Wireless WiFi Link 4965AGN chipset. The 802.11n mode can be disabled making it fall back to only use 802.11a/b/g modes casuing the connection to be much more stable and often the overall bandwidth will be better.

To check if your chipset is running with 802.11n enabled, enter the command:

sudo iwconfig wlan0

The output will look something like this:

wlan0 IEEE 802.11abgn ESSID:"XXXXXX" Mode:Managed Frequency:2.462 GHz Access Point: 00:0C:F6:82:90:28 Bit Rate=14.4 Mb/s Tx-Power=15 dBm Retry long limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:off Link Quality=51/70 Signal level=-59 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:66 Invalid misc:36 Missed beacon:0

If the first line says 802.11abgn your chipset has 802.11n activated.

To disable 802.11n mode do the following:

sudo modprobe -r iwl4965 sudo modprobe iwl4965 11n_disable=1

This will disable 802.11n until next reboot. Now check again with sudo iwconfig wlan0 and the output should display the first line without the “n” after 802.11, like this:

wlan0 IEEE 802.11abg ESSID:”XXXXXX”
Mode:Managed Frequency:2.462 GHz Access Point: 00:0C:F6:82:90:28
Bit Rate=54 Mb/s Tx-Power=15 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Encryption key:off
Power Management:off
Link Quality=46/70 Signal level=-64 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:7 Invalid misc:485 Missed beacon:0

If you want to make this change permanent, i.e. always disable 802.11n, do the following:

sudo echo "options iwl4965 11n_disable=1" >> /etc/modprobe.d/iwl4965.conf

After rebooting, verify using sudo iwconfig wlan0 that 802.11n is not enabled.

FON 2.0n router sharing 3G over Wifi

April 24, 2010/0 Comments/in Hardware, Wifi/by Stefan Helander

When you’re travelling as a professional nerd, you regularly needs to access the Internet. Internet cafés can be expensive and 3G… don’t think about using it abroad. It ususally costs a fortune.

I joined the FON network where you share your broadband connection at home to other FON-users and in return you are able to use the 1.5 million (and growing) FON hotsposts around the world for free.

In 2009 FON launched a new router, the FON 2.0n. It is packed with features (to read more about it, see FONs website), but most important is the USB port where it is possible to attach a 3G device. This enables you to share your 3G internet connection over the FON 2.0n wifi router. I usually bring this router on trips where I need to share my 3G internet connection to several computers over Wifi.

Vivotek PT7137 network camera connection problems

March 9, 2010/0 Comments/in Hardware/by Stefan Helander

I use the Vivotek PT7137 network camera connected through wifi/wlan to my network. Even though it is located only 7 meters from my accesspoint (with a couple of walls in between) the camera lost connection once in a while. And it wouldn’t reconnect unless I rebooted the camera. Upgrading to the latest firmware (v2.6 2009-04-14) didn’t improve either.

At the time my accesspoint was a DLINK DI-624+ broadband router and before I had time to dig into the problem any further, the DLINK passed away permanently and I got myself a Linksys WRT54GL which I pimped with Tomato. Now I had much better control over the wireless environment. I could boost the output on my Linksys to 80 mW (from the original 42) and the wireless survey helped me select a good channel with as little interference with my neighbours as possible. This helped a bit – the loss of connection occured more seldom. But they did still occur.

Finally I bought a small external antenna for the Vivotek in my local computer store. It has a 5 dB gain and a magnetic mount so I could move it around without moving the camera. This finally solved my problems and my camera haven’t lost it’s connection in months.

I still haven’t found the reason to the loss of connection. 7 meters should be no problem in a wifi/wlan environment. All other gadgets I connect through the same wireless network works without any problems. Possibly my Vivoteks wireless is broken or something in Vivoteks implementation makes it really sensetive to interference? I don’t know and honestly, I will not spend more time on it unless it causes me a problem again.

Siemens Gigaset WLAN camera vulnerability

September 12, 2009/0 Comments/in Hardware/by Stefan Helander

The Siemens Gigaset WLAN camera is vulnerable for unauthorized users to gain access through telnet and ftp by logging in as the user root. The user can log in without any password. When logged in, it is possible to view the cameras configuration file where the administrator password is stored in clear text.

The vulnerability is verified to exist in firmware version 1.27 but might be present in other versions too. At present time there are no updates available from Siemens later than version 1.27.

It is therefore a recommendation to maintain the Siemens Gigaset WLAN camera only on a private network or behind a firewall and to use an administrator password that is not used anywhere else.

Mysterious new mail icon in system tray

July 5, 2009/0 Comments/in Windows/by Stefan Helander

A new mail notification that occurs on the system tray looking like this:

Nothing will happen when you hover the mouse over it or clicking on it. It is hard to understand which software this icon belongs to.

The answer is Vodafone Mobile Connect which is a software used to connect with 3G mobile networks as well as WLAN/Wifi networks using built in devices in your computer. It is being shipped with HP Compaq laptop computers for example.

The icon indicates that you have new unread SMS messages in your mobile device. To read the SMS click on the red Vodafone Mobile Connect icon in the system tray. You can see a bit of the red icon in the right edge of the picture above. Then choose “Show” and then “SMS” in the Vodafone Mobile Connect software.

Posts