Wi-Fi: Difference between revisions

Revision as of 19:59, 4 January 2022

This page describes how to set up a wireless network connection with WPA encryption.

Prerequisites

Working wireless drivers

Note: in most cases installing linux-firmware should get you the required drivers

If you are using a Broadcom chipset, see the Broadcom Wi-Fi section.)

wpa_supplicant

To get started install wpa_supplicant

apk add wpa_supplicant

To list your available network interfaces:

Note: if you don't see any wireless interfaces (e.g. wlan0), you probably need to load and/or install drivers/firmware.

ip link

or

ip a

Bring up the desired interface:

ip link set wlan0 up

Note: If this errors with ioctl 0x8914 failed: No error information, that's busybox ip's way of saying your wireless radio is rfkill'd. See the Rfkill section for information on how to unblock your wireless radio.

Use this command to add your Wi-Fi network to wpa_supplicant:

wpa_passphrase 'ExampleWifiSSID' 'ExampleWifiPassword' > /etc/wpa_supplicant/wpa_supplicant.conf

(Access point not broadcasting its SSID requires additional line scan_ssid=1 in the file wpa_supplicant.conf)

Note: the Wi-Fi SSID and password are case sensitive and the single quote before and after the SSID and password need to be there

Start wpa_supplicant in the foreground to make sure the connection succeeds.

wpa_supplicant -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf

If all is well, run it as a daemon in the background by setting the -B option.

wpa_supplicant -B -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf

Configure the interface with an IP address.

udhcpc -i wlan0

Sanity check: the interface should have a inet address.

ip addr show wlan0

Automatic Configuration on System Boot

Add a entry for the desired interface (e.g. wlan0) to /etc/network/interfaces:

auto wlan0
iface wlan0 inet dhcp

Note: Dont remove or comment out the auto lo entry

Sanity check: Make sure /etc/wpa_supplicant/wpa_supplicant.conf is the correct configuration for the wireless access point you want to connect to.

Bring the interface down.

ip link set wlan0 down

Manually restart (or start) networking.

/etc/init.d/networking --quiet restart &

If all is well (feel free to confirm with the sanity checks),

Configure wpa_supplicant to start automatically on boot:

# rc-update add wpa_supplicant boot

Also make sure networking is set to automatically start on boot:

# rc-update add networking boot

Optional security precaution:

By default wpa_supplicant will store your Wi-Fi password in plain text:

Contents of (Example) /etc/wpa_supplicant/wpa_supplicant.conf

network={
	ssid="<YourSSIDShouldBeHere>"
        #psk="<YourPasswordShouldBeHereInPlainText>"
	psk=<RandomLettersAndNumbersShouldBeHere>
}

this is not necessary and wpa_supplicant should funtion just fine without it, if you dont want your stored password in plain text just delete the line with #psk="<YourPasswordShouldBeHere>" on it.

Launching udhcpc through wpa_cli actions

Todo: Figure out if theses two sections are different or connected to one another

With the above configuration, udhcpc will only run once at boot. If the Wifi isn't available then, or the network changes in between, it needs to be notified. This is done through the wpa_cli action script in /etc/wpa_supplicant/wpa_cli.sh

Automatic Reconnection when WIFI signal is lost

To enable automatic reconnection when wifi signal is lost add these to config:

Contents of /etc/wpa_supplicant/wpa_supplicant.conf

ap_scan=1
autoscan=periodic:10
disable_scan_offload=1

rc-update add wpa_cli boot

Troubleshooting

Broadcom Wi-Fi Chipset Users

The Broadcom chipset is quite popular among older computers. You will need to compile the firmware manually for this chipset as it is not included.

You can check if you have a Broadcom chipset by using dmesg:

dmesg | grep Broadcom

First install the SDK and Git:

apk add alpine-sdk git

Then git clone aports from git.alpinelinux.org.

git clone git://git.alpinelinux.org/aports

Change your directory to aports/non-free/b43-firmware, then build it.

Tip: You can't be root and must be a user of the group abuild (use groupadd f.e. addgroup $(whoami) abuild)

Tip: If this is your first time building a package you will need to generate a key for use in signing packages (use abuild-keygen -a -i)

abuild -r

Install the generated packge file (it will be in ~/packages/) - make sure to pass --allow-untrusted

apk add --allow-untrusted ~/packages/...pkg

Now we need fwcutter, which is executed from the firmware package:

apk add b43-fwcutter b43-firmware

Now you need to use modprobe so the device will show up:

modprobe b43

To automate this on startup add it to /etc/modules:

echo b43 >> /etc/modules

Now continue with the normal instructions.

Rfkill

Many laptops have a hardware button (or switch) to turn off wireless card, however, the card can also be blocked by kernel. This can be changed using rfkill. To show the current of your Wi-Fi:

Contents of (example) $ rfkill list

0: phy0: wlan
	Soft blocked: no
	Hard blocked: no

If the card is hard-blocked, use the hardware button or switch to unblock it. If the card is not hard-blocked but soft-blocked, use the following command:

# rfkill unblock wifi

@@ Line 107: / Line 107: @@
 '''Optional security precaution:'''
-By default wpa_supplicant will store your Wi-Fi password in plain text:
+By default {{Pkg|wpa_supplicant}} will store your Wi-Fi password in plain text:
 {{Cat|(Example) /etc/wpa_supplicant/wpa_supplicant.conf|<nowiki>network={