connect to wifi via commandline on arch

I just spent hours connecting to the wireless network on archlinux today. Finally I resorted to various tools in commandline. Here’s how I do it. Make sure you run the following commands as root to avoid some permission errors.

Find out SSID of the target wifi

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iw dev "your_interface" scan | less

Replace your_interface with your own one, usually it’s wlp3s0 or wlan0. You can run ifconfig to find out the name of your interface

You will get something like

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BSS fc:d7:33:59:74:74(on wlp3s0) -- associated
TSF: 85505115422 usec (0d, 23:45:05)
freq: 2412
beacon interval: 100 TUs
capability: ESS Privacy ShortPreamble ShortSlotTime (0x0431)
signal: -54.00 dBm
last seen: 136 ms ago
Information elements from Probe Response frame:
SSID: TP-LINK_7474
Supported rates: 1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0
...

The SSID is something after SSID. It’s TP-LINK_7474 in my case.

Association

After finding out your SSID, you would need to connect to it. There are two cases here, one is when there’s no encryption and one is when WPA/WPA2 is enabled. Find the case that suits you most.

No Encryption

This is pretty easy, you only need one line here.

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iw dev wlan0 connect "your_essid"

your_essid is the name of the network you found out before, such as TP-LINK_7474

Then you will need to Get an IP address

WPA/WPA2

You have a lot of work to be done here. First create a new file /etc/wpa_supplicant/wpa_supplicant.conf. Type in the following contents and save it.

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ctrl_interface=/var/run/wpa_supplicant
update_config=1

Generate passphrase and save it to the above file. Replace your_SSID and your_key with your own ones.

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wpa_passphrase "your_SSID" "your_key" >> /etc/wpa_supplicant/wpa_supplicant.conf

Check if wpa_supplicant is running.

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ps -aux|grep wpa_supplicant

If it’s running, just as follows

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root 21108 0.0 0.0 43488 3260 ? Ss 20:01 0:00 wpa_supplicant -i wlp3s0 -B -c /etc/wpa_supplicant/wpa_supplicant.conf

Kill the process, and remove /var/run/wpa_supplicant/ if it exists

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kill 21108
rm /var/run/wpa_supplicant -rf

If it’s not running or you’ve killed the running one, run the following command to start wpa_supplicant.

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wpa_supplicant -B -i "your_interface" -c /etc/wpa_supplicant/wpa_supplicant.conf

Get IP Address

After connect to the network, you need to get an IP using dhcpcd

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dhcpcd wlp3s0

Wait for several seconds. If everything went smoothly, you would be connected to the network successfully.

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