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.
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)
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" }
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.