How to setup a WLAN connection

Applicable for

STM32MP13x lines, STM32MP15x lines, Unknown MPU, Unknown MPU, STM32MP25x lines

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Even if the example is related to the RTL8723BU chip (this chip calls for a WiFi (minimally 802.11g/n) and Bluetooth 4.0 LE), most of the commands are generic ones and can be applied to any platform.

1. ifconfig

Verify the wlan0 interface is present (that means drivers have been started and the WiFi firmware loaded):

1.1. Check WLAN interface

ifconfig -a
lo        Link encap:Local Loopback  
         LOOPBACK  MTU:65536  Metric:1
         RX packets:0 errors:0 dropped:0 overruns:0 frame:0
         TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000 
         RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

wlan0     Link encap:Ethernet  HWaddr 60:F1:89:3F:F6:0E  
         BROADCAST MULTICAST  MTU:1500  Metric:1
         RX packets:0 errors:0 dropped:0 overruns:0 frame:0
         TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000 
         RX bytes:0 (0.0 B)  TX bytes:10 (10.0 B)

1.2. Initialize WLAN interface

ifconfig wlan0  192.168.43.135  broadcast 192.168.43.255  netmask 255.255.255.0

ifconfig wlan0 up

ifconfig wlan0 
wlan0     Link encap:Ethernet  HWaddr 60:F1:89:3F:F6:0E  
         inet addr:192.168.43.135  Bcast:192.168.43.255  Mask:255.255.255.0
         UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1                   /* UP indicate that your interface is UP */
         RX packets:19 errors:0 dropped:0 overruns:0 frame:0
         TX packets:19 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000 
         RX bytes:1774 (1.7 KiB)  TX bytes:2326 (2.2 KiB)

2. iw

The next phase is to scan for any wireless access points with the command:

2.1. Scan available SSID (AP)

• Get only SSID name

iw dev wlan0 scan |grep SSID
       SSID: NETWORK1
       SSID: NETWORK2

• List full SSID information

iw dev wlan0 scan
BSS 00:23:5e:4a:28:f9(on wlan0)
       TSF: 0 usec (0d, 00:00:00)
       freq: 2412
       beacon interval: 100 TUs
       capability: ESS ShortPreamble ShortSlotTime (0x0421)
       signal: -72.00 dBm
       last seen: 0 ms ago
       SSID: NETWORK1
       Supported rates: 1.0* 2.0* 5.5* 6.0 9.0 11.0* 12.0 18.0 
       DS Parameter set: channel 1
       TIM: DTIM Count 0 DTIM Period 1 Bitmap Control 0x0 Bitmap[0] 0x2
       Country: FR     Environment: Indoor/Outdoor
               Channels [1 - 13] @ 20 dBm
       BSS Load:
                * station count: 1
                * channel utilisation: 30/255
                * available admission capacity: 23437 [*32us]
       ERP: <no flags>
       Extended supported rates: 24.0 36.0 48.0 54.0 
       WMM:     * Parameter version 1
                * u-APSD
                * BE: CW 15-1023, AIFSN 3
                * BK: CW 15-1023, AIFSN 7
                * VI: CW 7-15, AIFSN 2, TXOP 3008 usec
                * VO: CW 3-7, AIFSN 2, TXOP 1504 usec
BSS 00:23:5e:96:57:20(on wlan0)
       TSF: 0 usec (0d, 00:00:00)
       freq: 2412
       beacon interval: 100 TUs
       capability: ESS Privacy ShortPreamble ShortSlotTime (0x0431)
       signal: -66.00 dBm
       last seen: 0 ms ago
       SSID: NETWORK2
       Supported rates: 1.0* 2.0* 5.5* 6.0 9.0 11.0* 12.0 18.0 
       DS Parameter set: channel 1
       Country: FR     Environment: Indoor/Outdoor
               Channels [1 - 13] @ 20 dBm
       BSS Load:
                * station count: 8
                * channel utilisation: 48/255
                * available admission capacity: 23437 [*32us]
       ERP: <no flags>
       RSN:     * Version: 1
                * Group cipher: CCMP
                * Pairwise ciphers: CCMP
                * Authentication suites: IEEE 802.1X 00-40-96:0
                * Capabilities: 4-PTKSA-RC 4-GTKSA-RC (0x0028)
       Extended supported rates: 24.0 36.0 48.0 54.0 
       WMM:     * Parameter version 1
                * u-APSD
                * BE: CW 15-1023, AIFSN 3
                * BK: CW 15-1023, AIFSN 7
                * VI: CW 7-15, AIFSN 2, TXOP 3008 usec
                * VO: CW 3-7, AIFSN 2, TXOP 1504 usec

3. Automatic WiFi configuration at start up

3.1. networkctl

Systemd has a specific service for the network named systemd-networkd, this service comes with the tool networkctl which allows to show the status of each network interface.

networkctl --no-pager
 IDX LINK             TYPE               OPERATIONAL SETUP     
 1 lo               loopback           carrier     unmanaged 
 2 eth0             ether              routable    configured
 3 sit0             sit                no-carrier         unmanaged 
 4 ip6tnl0          tunnel6            no-carrier         unmanaged 
 5 wlan0            wlan               no-carrier         unmanaged 
 6 wlan1            wlan               no-carrier         unmanaged 

6 links listed.

We can see that the eth0 interface is managed by networked via the information configured and the interface is used (routable).

3.2. How to set a wireless configuration with networkd

The goal is to configure an wlan network interface via systemd-networkd configuration.
All the network configurations are stored on /lib/systemd/network or /etc/systemd/network
Create the file dedicated to wireless interface "/lib/systemd/network/51-wireless.network" :

echo "[Match]" > /lib/systemd/network/51-wireless.network
echo "Name=wlan0" >> /lib/systemd/network/51-wireless.network
echo "[Network]" >> /lib/systemd/network/51-wireless.network
echo "DHCP=ipv4" >> /lib/systemd/network/51-wireless.network

Check content is as follow

cat   /lib/systemd/network/51-wireless.network
 [Match]
 Name=wlan0
 [Network]
 DHCP=ipv4

For attaching this wireless interface to a specific network, we need to have some information like SSID of network and password.

To see the list of wireless network available:

ifconfig wlan0 up
iw dev wlan0 scan |grep SSID
       SSID: NETWORK1
       SSID: NETWORK2

Associate the wireless network to wireless interface, here wlan0:

mkdir -p /etc/wpa_supplicant/
         echo "ctrl_interface=/var/run/wpa_supplicant" > /etc/wpa_supplicant/wpa_supplicant-wlan0.conf
         echo "eapol_version=1" >> /etc/wpa_supplicant/wpa_supplicant-wlan0.conf
         echo "ap_scan=1" >> /etc/wpa_supplicant/wpa_supplicant-wlan0.conf
         echo "fast_reauth=1" >> /etc/wpa_supplicant/wpa_supplicant-wlan0.conf
         echo "" >> /etc/wpa_supplicant/wpa_supplicant-wlan0.conf
         wpa_passphrase SSID_OF_NETWORK PASSWORD_OF_NETWORK >> /etc/wpa_supplicant/wpa_supplicant-wlan0.conf

Where SSID_OF_NETWORK PASSWORD_OF_NETWORK correspond to the SSID and password of wireless network.

Information

the name of file on /etc/wpa_supplicant must contains the name of wireless interface: wpa_supplicant-wlan0.conf

To enable and start the wireless configuration:

systemctl enable wpa_supplicant@wlan0.service
         systemctl restart systemd-networkd.service
         systemctl restart wpa_supplicant@wlan0.service

4. Wlan Network attachment (without system which manage systemd-networkd configuration)

Warning

dhclient is not available in the OpenSTLinux because system.networkd already inbeds a dhcp client. On OSTL, it is recommended to follow the chapter #Automatic_WiFi_configuration_at_start_up

4.1. Configure your WiFi connection

Configure WiFi connection by using wpa_supplicant tool

• Check current configuration

cat /etc/wpa_supplicant.conf
ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=0
update_config=1
network={
   key_mgmt=NONE
}

• Set the WiFi network name and password

wpa_passphrase <your_ssid_name> <your_ssid_key> >> /etc/wpa_supplicant.conf

• Check new configuration

cat /etc/wpa_supplicant.conf
ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=0
update_config=1
network={
       ssid="your_ssid_name"
       psk="your_ssid_key"
}

Information

If no WPA key replace psk=... with key_mgmt=NONE

4.1.1. Connect to SSID

wpa_supplicant -B -iwlan0 -c /etc/wpa_supplicant.conf
Successfully initialized wpa_supplicant

4.1.2. link to SSID

iw wlan0 link
       SSID: NETWORK1
       freq: 2462
       RX: 501 bytes (3 packets)
       TX: 4056 bytes (22 packets)
       signal: -75 dBm
       tx bitrate: 12.0 MBit/s
       bss flags:      short-preamble short-slot-time
       dtim period:    1
       beacon int:     100

4.1.3. Assign IP address to WLAN interface

Use the DHCP client to obtain an address (assuming wireless network (associated to) has a DHCP server):

dhclient wlan0

Use the ip command to verify the IP address assigned by the DHCP. The IP address is 192.168.43.135 from below.

 ip addr show wlan0
 3: wlan0:  mtu 1500 qdisc mq state UP qlen 1000
   link/ether 74:e5:43:a1:ce:65 brd ff:ff:ff:ff:ff:ff
   inet 192.168.43.135/24 brd 192.168.1.255 scope global wlan0
   inet6 fe80::76e5:43ff:fea1:ce65/64 scope link 
      valid_lft forever preferred_lft forever

4.1.4. Check connectivity

The most basic connectivity test is to use the “ping” command. In this example, the wireless router (associated to) has an IP address of 192.168.43.1:

ping 192.168.43.1
PING 192.168.43.1 (192.168.43.1): 56 data bytes
64 bytes from 192.168.43.1: seq=0 ttl=64 time=14.905 ms
64 bytes from 192.168.43.1: seq=1 ttl=64 time=30.387 ms
64 bytes from 192.168.43.1: seq=2 ttl=64 time=20.462 ms

• Note : Enter <CTRL+C> to terminate the ping session.

Microprocessor unit

Receive

Transmit

uniprocessor

Dynamic host configuration pProtocol (see https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol for more details)