Wi-Fi

2018-04-02T06:31:02Z

Strfry: Launching udhcpc through wpa_cli actions

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 [[#Broadcom_Wi-Fi_Chipset_Users|section at the bottom of this post]].)

Install {{Pkg|wireless-tools}} and {{Pkg|wpa_supplicant}}.
{{Cmd|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.)
{{Cmd|ip link set wlan0 up}}

Find a network to connect to. Look for the ESSID. In this example we will use the ESSID "MyNet".
{{Cmd|iwlist wlan0 scanning}}

Configure the wlan0 interface to associate with the MyNet ESSID:
{{Cmd|iwconfig wlan0 essid MyNet}}

Print its configuration, to check:
{{Cmd|iwconfig wlan0}}

Create a wpa_supplicant configuration stanza for wpa_supplicant by executing the following:
{{Cmd|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 {{Path|wpa.conf}} which includes the pre-shared key.

From one terminal/console, start wpa_supplicant with the generated config:
{{Cmd|wpa_supplicant -Dwext -iwlan0 -c ./wpa.conf}}

From another terminal/console, start dhcpcd:
{{Cmd|udhcpc -i wlan0}}

The wlan0 interface should be configured with an IP address at this point:
{{Cmd|ifconfig wlan0}}

== Automatic Configuration on System Boot ==

Add an interface stanza for wlan0 to the file {{Path|/etc/network/interfaces}}

<pre>
auto wlan0
iface wlan0 inet dhcp
</pre>

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

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

Test the automatic interface configuration:

Bring the interface down:

{{Cmd|ifconfig wlan0 down}}

Manually start wpa_supplicant

{{Cmd|/etc/init.d/wpa_supplicant start}}

The wlan0 interface should be associated with the MyNet SSID:

{{Cmd|iwconfig wlan0}}

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

{{Cmd|ifconfig wlan0}}

Configure wpa_supplicant to start automatically on boot:

{{Cmd|rc-update add wpa_supplicant boot}}

Reboot:

{{Cmd|reboot}}

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

{{Cmd|iwconfig wlan0}}

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

{{Cmd|ifconfig wlan0 {{!}} grep addr}}

=== Launching udhcpc through wpa_cli actions ===

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

{{Cmd|rc-update add wpa_cli boot}}

== 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:

{{Cmd|dmesg {{!}} grep Broadcom}}

First install the SDK an Git:
{{Cmd|apk add alpine-sdk git}}

Then git clone aports from git.alpinelinux.org.

{{Cmd|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. '''groupadd $(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''')}}

{{Cmd|abuild -r}}

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

{{Cmd|apk add --allow-untrusted ~/packages/...pkg}}

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

{{Cmd|apk add b43-fwcutter b43-firmware}}

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

{{Cmd|modprobe b43}}

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

{{Cmd|echo b43 >> /etc/modules}}

Now continue with the normal instructions.

[[Category:Networking]]

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Wi-Fi