Difference between revisions of "Connecting to a wireless access point"

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This document describes how to set up a wireless network connection with WPA encryption.
 
This document describes how to set up a wireless network connection with WPA encryption.
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== 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]].)
 
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}}.
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Install {{Pkg|wireless-tools}} and {{Pkg|wpa_supplicant}}, which are probably available to be installed in the base setup.
 
{{Cmd|apk add wireless-tools wpa_supplicant}}
 
{{Cmd|apk add wireless-tools wpa_supplicant}}
  
Bring the link up so we can look for wireless networks. (An error here means you probably need extra drivers/firmware.)
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== Manual Configuration  ==
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List your available network interfaces. If you don't see any wireless interfaces (e.g. {{Path|wlan0}}), you probably need to load and/or install extra drivers/firmware.
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{{Cmd|ip link}}
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Bring the desired interface up.
 
{{Cmd|ip link set wlan0 up}}
 
{{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".
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{{Note|If this errors with <code>ioctl 0x8914 failed: No error information</code>, that's <code>busybox ip</code>'s way of saying your wireless radio is rfkill'd. See [https://wiki.archlinux.org/index.php/Wireless_network_configuration#Rfkill_caveat here] for information on how to unblock your wireless radio; the base installation should have <code>busybox rfkill</code> available.}}
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Use the interface to scan for wireless access points. Make sure the ESSID you want to connect to appears here.
 
{{Cmd|iwlist wlan0 scanning}}
 
{{Cmd|iwlist wlan0 scanning}}
  
Let's set the ESSID:
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Associate the interface with desired ESSID.
{{Cmd|iwconfig wlan0 essid MyNet}}
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{{Cmd|iwconfig wlan0 essid ExampleWifi}}
  
We need to create a shared key for wpa_supplicant.
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Sanity check: the interface should be configured with {{Path|ESSID:"ExampleWifi"}}.
{{Cmd|wpa_passphrase MyNet > wpa.conf}}
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{{Cmd|iwconfig wlan0}}
It will wait for the password from stdin. Enter the password and enter. Now you will have a {{Path|wpa.conf}} file with the preshared key.
 
  
Start wpa_supplicant with the generated config:
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Create a wpa_supplicant configuration stanza for the wireless access point.
{{Cmd|wpa_supplicant -Dwext -iwlan0 -c ./wpa.conf}}
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{{Cmd|wpa_passphrase 'ExampleWifi' 'ExampleWifiPassword' > /etc/wpa_supplicant/wpa_supplicant.conf}}
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''(Access point not broadcasting its SSID requires additional line <code>scan_ssid=1</code> in the file <code>wpa_supplicant.conf</code>)''
  
From another console, start dhcpcd:
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Start wpa_supplicant in the foreground to make sure the connection succeeds.
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{{Cmd|wpa_supplicant -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf}}
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If all is well, run it as a daemon in the background by setting the {{Path|-B}} option.
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{{Cmd|wpa_supplicant -B -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf}}
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Configure the interface with an IP address.
 
{{Cmd|udhcpc -i wlan0}}
 
{{Cmd|udhcpc -i wlan0}}
  
You should get an IP address.
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Sanity check: the interface should have an {{Path|inet}} address.
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{{Cmd|ip addr show wlan0}}
  
You then want to make the connection process automatic on boot-up. Open {{Path|/etc/network/interfaces}} and add the following stanza:
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== Automatic Configuration on System Boot  ==
auto wlan0
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iface wlan0 inet dhcp
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Add a stanza for the desired interface (e.g. {{Path|wlan0}}) to {{Path|/etc/network/interfaces}}:
{{Note|I had to append `pre-up iwconfig wlan0 essid <ESSID>` to automatically connect to the network.}}
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<pre>
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auto wlan0
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iface wlan0 inet dhcp
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</pre>
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Make sure {{Path|/etc/wpa_supplicant/wpa_supplicant.conf}} is the correct configuration for the wireless access point you want to connect to.
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Bring the interface down.
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{{Cmd|ifconfig wlan0 down}}
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Manually start wpa_supplicant.
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{{Cmd|/etc/init.d/wpa_supplicant start}}
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If all is well (confirm with the sanity checks in [[#Manual_Configuration|Manual Configuration]]), configure wpa_supplicant to start automatically on boot.
  
You will also need to set wpa_supplicant to start automatically on boot:
 
 
{{Cmd|rc-update add wpa_supplicant boot}}
 
{{Cmd|rc-update add wpa_supplicant boot}}
  
Next, create {{Path|/etc/wpa_supplicant/}} (permissions of 755 with root:root are fine), and move {{Path|wpa.conf}} into that folder, renaming it to {{Path|wpa_supplicant.conf}}.
 
  
Reboot and check that you are associated with the access point:
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=== Launching udhcpc through wpa_cli actions ===
{{Cmd|iwconfig wlan0}}
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and check that you got a DHCP lease:
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With the above configuration, udhcpc will only run once at boot.
{{Cmd|ifconfig wlan0 {{!}} grep addr}}
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If the Wifi isn't available then, or the network changes in between, it needs to be notified.
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This is done through the wpa_cli action script in /etc/wpa_supplicant/wpa_cli.sh
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{{Cmd|rc-update add wpa_cli boot}}
  
 
== Broadcom Wi-Fi Chipset Users  ==
 
== Broadcom Wi-Fi Chipset Users  ==
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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.  
 
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.  
  
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Then git clone aports from git.alpinelinux.org.
 
Then git clone aports from git.alpinelinux.org.
  
(remove $, new users can't add links to the wiki)
 
  
{{Cmd|git clone git://git.alpinelinux.org/abuild}}
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{{Cmd|git clone git://git.alpinelinux.org/aports}}
  
 
Change your directory to '''aports/non-free/b43-firmware''', then build it.
 
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)''
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{{Tip|You can't be root and must be a user of the group abuild (use groupadd f.e. '''addgroup $(whoami) abuild''')}}
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{{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}}
 
{{Cmd|abuild -r}}

Latest revision as of 14:31, 7 May 2020

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, which are probably available to be installed in the base setup.

apk add wireless-tools wpa_supplicant

Manual Configuration

List your available network interfaces. If you don't see any wireless interfaces (e.g. wlan0), you probably need to load and/or install extra drivers/firmware.

ip link

Bring the desired interface up.

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 here for information on how to unblock your wireless radio; the base installation should have busybox rfkill available.


Use the interface to scan for wireless access points. Make sure the ESSID you want to connect to appears here.

iwlist wlan0 scanning

Associate the interface with desired ESSID.

iwconfig wlan0 essid ExampleWifi

Sanity check: the interface should be configured with ESSID:"ExampleWifi".

iwconfig wlan0

Create a wpa_supplicant configuration stanza for the wireless access point.

wpa_passphrase 'ExampleWifi' '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)


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 an inet address.

ip addr show wlan0

Automatic Configuration on System Boot

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

auto wlan0
iface wlan0 inet dhcp

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.

ifconfig wlan0 down

Manually start wpa_supplicant.

/etc/init.d/wpa_supplicant start

If all is well (confirm with the sanity checks in Manual Configuration), configure wpa_supplicant to start automatically on boot.

rc-update add wpa_supplicant boot


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

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:

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.

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.