How to setup wifi connection



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[edit]

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

1.1 Check WLAN interface[edit]

Board $> 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[edit]

Board $> ifconfig wlan0 up
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[edit]

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

2.1 Scan available SSID (AP)[edit]

  • Get only SSID name
Board $> iw dev wlan0 scan |grep SSID
       SSID: NETWORK1
       SSID: NETWORK2
  • List full SSID information
Board $> 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 Wlan Network attachment (without system which manage systemd-networkd configuration)[edit]

3.1 Configure your WiFi connection[edit]

Configure WiFi connection by using wpa_supplicant tool

  • Check current configuration
Board $> 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
Board $> wpa_passphrase <your_ssid_name> <your_ssid_key> >> /etc/wpa_supplicant.conf
  • Check new configuration
Board $> 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"
}
Info.png If no WPA key replace psk=... with key_mgmt=NONE

3.1.1 Connect to SSID[edit]

Board $> wpa_supplicant -B -iwlan0 -c /etc/wpa_supplicant.conf
Successfully initialized wpa_supplicant

3.1.2 link to SSID[edit]

Board $> 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

3.1.3 Assign IP address to WLAN interface[edit]

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

Board $> 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.

 Board $> 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

3.1.4 Check connectivity[edit]

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:

Board $> 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.

4 Automatic WiFi configuration at start up[edit]

4.1 networkctl[edit]

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.

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

4.2 How to set a wireless configuration with networkd[edit]

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:

Board $> 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:

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

Associate the wireless network to wireless interface, here wlan0:

Board $> 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.

Info.png 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:

Board $> systemctl enable wpa_supplicant@wlan0.service
         systemctl restart systemd-networkd.service
         systemctl restart wpa_supplicant@wlan0.service

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