Wifi

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TODO: {{#todo:InProgress (10.20.2015-14:23->JJ+);(10.20.2015-13:43->JJ+);(10.23.2015-11:50->MD-);(10.26.2015-16:50->JJ+);(10.27.2015-15:30->JJ+)|Jeffrey Jung|OE 5.0,InProgress,JJ,MD}}

This guide will illustrate how to set up and connect to a wireless network using the ThinkPenguin Wireless N USB Adapter for GNU/Linux and the built-in WiFi on the SoM-200GS.


Background

While some machines from EMAC are not natively designed to connect to wireless networks, a large amount of these systems do have USB ports. Using a wireless network USB adapter, like one found here at ThinkPenguin, the system can be modified to establish wireless network connections. This page describes the actions needed to take to connect to a wireless network either using a wireless network USB adapter or built-in Wi-Fi found on EMAC products like the SoM-200GS carrier. We chose to use the ThinkPenguin USB adapter for this page because it is targeted to work with most, if not all, Linux distributions.


General Information

Set Up

Before the device can be connected to the network, some additional software will need to be installed. In order to obtain the new packages, connect the system to a physical network. If your are going to be using the USB adapter for the connection, it may be plugged in at this time, although it may not have the proper drivers installed to the system yet.

  1. This process requires modifying some system files so start by enabling read and write permissions to the filesystem.

    root@ipac9x25:~# mount -o remount,rw /

  2. A check for any updates is typically a good practice before installing new software. Us the opkg manager to install any updated software from the package list.

    root@ipac9x25:~# opkg update

  3. One of the best tools to establish the connection to wireless networks is the wpa-supplicant package. This supplicant will allow the system to make connections to WPA and WPA2 protected networks. Install this package with the opkg manager.

    root@ipac9x25:~# opkg install wpa-supplicant

  4. If using the USB adapter, the appropriate drivers may need to be installed. The ThinkPenguin USB adapter requires the installment of the linux-firmware-ath9k package.

    root@ipac9x25:~# opkg install linux-firmware-ath9k

  5. If using built-in Wi-Fi, the marvel license and linux-firmware-sd8787 packages will need to be installed.

    root@som9g45:~# opkg install linux-firmware-marvel-license
    root@som9g45:~# opkg install linux-firmware-sd8787

  6. Independent of using built-in Wi-Fi or an adapter, the iw and wireless-tools packages will complete the needed software to get a connection started.

    root@ipac9x25:~# opgk install iw
    root@ipac9x25:~# opkg install wireless-tools


  7. Upon successful installation of all required packages, the system will need to be rebooted to take advantage of the new packages.

    root@ipac9x25:~# reboot


Wireless Networking

Using the packages that have just been installed, the system can be connected to the wireless network.
1. Changes to some configuration files will be necessary, so mount the filesystem to read and write permissions.

root@ipac9x25:~# mount -o remount,rw /

2. Wireless networks can be found using the can option of iw.

root@ipac9x25:~# iw dev wlan0 scan
A detailed list of the nearby networks will be printed out to the terminal. To identify the SSIDs and respective signal strengths of the network(s) easier, pipe the iw command with the scan option into grep using keywords "SSID" or "signal". The closer the value of the signal strength is to 0, the stronger the connection.
root@ipac9x25:~# iw dev wlan0 scan | grep SSID
SSID: EMAC-A
root@ipac9x25:~# iw dev wlan0 scan | grep signal
signal: -78.00dBm
root@ipac9x25:~#


The /etc/wpa_supplicant.conf file will need to be modified in a specific manner depending on the protection type of the network.


3. For an open network, you'll just need to uncomment the lines in /etc/wpa_supplicant.conf 

###open network
#network={
#      ssid="your-ssid" (optional)
#      scan_ssid=1
#       key_mgmt=NONE
#}


4. Networks protected by either WEP or WPA2 encryption will need a private shared key (psk) generated for the specific network and its password. To get the psk, use wpa_passphrase with the SSID and password for the desired network as arguments.

root@ipac9x25:~# wpa_passphrase SSID Password

network={

ssid="SSID"
#psk="Password"
psk=b99d2c0fb66194f93ad52b71051e1095dc76e12529321334b3feb18332608eb7

}

root@ipac9x25:~#


SSID is the SSID of the preferred network found when scanning with iw. Password is the password to connect to the network.


5. The psk that wpa_passphrase creates is long and complicated so highlight and copy it. Remember the name of the SSID

6. Use vim or another command line editor to write the SSID and paste the psk in the appropriate lines within /etc/wpa_supplicant.conf

network={

ssid="SSID"
proto=WPA
key_mgmt=WPA-PSK
psk=b99d2c0fb66194f93ad52b71051e1095dc76e12529321334b3feb18332608eb7

}
~
~
~
~
~
-- INSERT --


7. The path /etc/init.d/wpa_supplicant with the argument start will attempt to establish a connection with the network.

root@ipac9x25:~# /etc/init.d/wpa_supplicant start
As the command is running, watch the terminal output for the status of the connection. A connection has been established when output stops and the last line reads:
IPv6 ADDRCONF(NETDEV_CHANGE):wlan0: link becomes ready

A connection has failed if output to the terminal continues and the following line is seen repeatedly:

IPv6: ADDRCONF(NETDEV_UP):wlan0: link is not ready


Successful connection (waiting a full minute to ensure output to the terminal stopped);
root@ipac9x25:~# /etc/init.d/wpa-supplicant start

Successfully initialized wpa_supplicant
rfkill: Cannot open RFKILL control device

root@ipac9x25:~# wlan0: authenticate with 1c:7e:e5:40:10:fd

wlan0: send auth to 1c:7e:e5:40:10:fd (try 1/3)
wlan0: send auth to 1c:7e:e5:40:10:fd (try 2/3)
wlan0: authenticated
wlan0: associating with AP with corrupt beacon
wlan0: associate with 1c:7e:e5:40:10:fd (try 1/3)
wlan0: RX AssocResp from 1c:7e:e5:40:10:fd (capab=0x431 status=0 aid=6)
wlan0: associated
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready

Failed connection (waiting more than a minute as output continues to print to the terminal). The repeated lines indicate an issue establishing the connection.
root@ipac9x25:~# /etc/init.d/wpa-supplicant start

Successfully initialized wpa_supplicant IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready

root@ipac9x25:~# IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready

cfg80211: Calling CRDA to update world regulatory domain
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
cfg80211: Calling CRDA to update world regulatory domain
IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
cfg80211: Calling CRDA to update world regulatory domain
IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
cfg80211: Calling CRDA to update world regulatory domain
IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
cfg80211: Calling CRDA to update world regulatory domain
IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
cfg80211: Calling CRDA to update world regulatory domain
IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
cfg80211: Calling CRDA to update world regulatory domain
IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready

A failed connection is likely the result of an improper password. Use wpa_passphrase to make sure you have the right psk for the password.


8. The ifconfig command will be used to determine that the device is wirelessly connected to the network. Look to see that wlan0 has an IP address.

wlan0 Link encap:Ethernet HWaddr A8:54:B2:42:89:8D

inet addr:10.0.4.148 Bcast:10.0.255.255 Mask:255.255.0.0
UP BROADCAST RUNNING MULTICAST MTU:1500 METRIC:1
RX packets:3395 errors:0 dropped:6 overruns:0 frame:0
TX packets:60 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:346619 (338.4 KiB) TX bytes:6318 (6.1 Kib)


9. Disconnect any physical connections from the system and ping to www.emacinc.com to verify that the system can wirelessly connect to the Internet.

root@ipac9x25:~# ping -c www.emacinc.com

PING www.emacinc.com (172.16.0.10): 56 data bytes
64 bytes from 172.16.0.10: seq=0 ttl=63 time=1.910 ms
64 bytes from 172.16.0.10: seq=1 ttl=63 time=1.748 ms
64 bytes from 172.16.0.10: seq=2 ttl=63 time=2.061 ms

--- www.emacinc.com ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 1.748/1.906/2.061 ms

root@ipac9x25:~#



Conclusion

This page walks through the procedure to connect a module to a wireless network via a Wi-Fi adapter or built-in wireless, as well as acquiring the necessary software tools to make the connection for the first time. While there are plenty of USB wireless adapters available for sale, we used an adapter intended for use on Linux machines with a driver supported by the EMAC OE SDK. Other USB wireless adapters may be attempted to connect EMAC devices to wireless networks, but may face issues with driver support or other compatibility issues. We recommend using the USB adapter from ThinkPenguin.

After connecting to a network the first time, the system will be able to connect to the same network when rebooted or powered on. Connecting to a new network will require going through the procedures set out under the Wireless Networking section.


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