engledow.me

Steve Engledow: Senior Solutions Builder at Amazon Web Services

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29 April 2015

Why-fi?

tags:

I’m an arch linux user and I love it; there’s no other distro for me. The things that arch gets criticism for are the exact same reasons I love it and they all more or less boil down to one thing: arch does not hold your hand.

It’s been a while since an update in arch caused me any problems but it did today.

It seems there’s an issue with the latest version of wpa_supplicant which renders it incompatible with the way wifi is setup at boot time. The problem was caught and resolved very quickly by package maintainers who simply rolled the wpa_supplicant package back. However, I was unlucky enough to have caught the intervening upgrade shortly before turning my laptop off. I came home this evening to find I had no wifi!

This wasn’t a huge challenge but I haven’t written a blog post for a while and someone might find this useful:


If your wifi doesn’t start at boot…

And you’re using a laptop with no ethernet port

And you know an upgrade will solve your problem…

How do you get internet so you can upgrade?

Simples :)

The steps

First, find the name of your wireless interface:

iw dev

Which will output something like:

phy#0
    Interface wlp2s0
        ifindex 2
        wdev 0x1
        addr e8:b1:fc:6c:bf:b5
        type managed
        channel 11 (2462 MHz), width: 20 MHz, center1: 2462 MHz

Where wlp2s0 is the bit we’re interested in.

Now bring the interface up:

ip link set wlp2s0 up

Connect to the access point:

iw dev wlp2s0 connect "AP name"

Create a temporary configuration file for wpa_supplicant:

wpa_passphrase "AP name" "password" > /tmp/wpa.config

Run wpa_supplicant to authenticate with the access point:

wpa_supplication -iwlp2s0 -c/tmp/wpa.config

In another terminal (or you could have backgrounded the above), run dhcpcd to get an IP address from your router:

dhcpcd wlp2s0

Update and reboot or whatever :)