Connecting to a wireless access point

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

Install necessary drivers and software

First make sure your wireless drivers are loaded properly. (if you are using a Broadcom chipset, see the section at the bottom of this post.)

Install wireless-tools and wpa_supplicant.

apk add wireless-tools wpa_supplicant

Manual Configuration

Bring the link up so we can look for wireless networks. (An error here means you probably need extra drivers/firmware.)

ip link set wlan0 up

Find a network to connect to. Look for the ESSID. In this example we will use the ESSID "MyNet".

iwlist wlan0 scanning

Configure the wlan0 interface to associate with the MyNet ESSID:

iwconfig wlan0 essid MyNet

Print its configuration, to check:

iwconfig wlan0

Create a wpa_supplicant configuration stanza for wpa_supplicant by executing the following:

wpa_passphrase MyNet > wpa.conf

wpa_passphrase expects the password to be passed via stdin.

So, type the password and press ENTER.

The above commands creates the file wpa.conf which includes the pre-shared key.

From one terminal/console, start wpa_supplicant with the generated config:

wpa_supplicant -Dwext -iwlan0 -c ./wpa.conf

From another terminal/console, start dhcpcd:

udhcpc -i wlan0

The wlan0 interface should be configured with an IP address at this point:

ifconfig wlan0

Automatic Configuration on System Boot

Add an interface stanza for wlan0 to the file /etc/network/interfaces

auto wlan0
iface wlan0 inet dhcp

Create /etc/wpa_supplicant if it doesn't already exist, set sane permissions and append the configuration wpa.conf to wpa_supplicant.conf.

mkdir -p /etc/wpa_supplicant
chmod 750 /etc/wpa_supplicant
cat wpa.conf >> /etc/wpa_supplicant/wpa_supplicant.conf

Test the automatic interface configuration:

Bring the interface down:

ifconfig wlan0 down

Manually start wpa_supplicant

/etc/init.d/wpa_supplicant start

The wlan0 interface should be associated with the MyNet SSID:

iwconfig wlan0

The wlan0 interface should have been assigned an IP address via DHCP:

ifconfig wlan0

Configure wpa_supplicant to start automatically on boot:

rc-update add wpa_supplicant boot

Reboot:

reboot

Log in and check that the interface is associated with the access point:

iwconfig wlan0

Check that the interface was assigned an IP address via DHCP:

ifconfig wlan0 | grep addr

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 an 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.

You can't be root and must be a user of the group abuild (use groupadd)

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.