admin:linux:cli:wpa_supplicant [~wiki]

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====== Connect to a wireless network with wpa_supplicant ======

If your usual GUI program to connect to wifi networks, e.g. [[:admin:linux:gui:wicd]] or [[:admin:linux:networkmanager|NetworkManager]] is not available, you can connect to a wireless network by manually scanning and editing wpa_supplicant's config files.

//see also: [[https://wiki.archlinux.org/index.php/WPA_supplicant|Arch Wiki on wpa_supplicant]]//

===== one-liner to connect with known SSID and passphrase =====

Run this on a root shell. ''sudo'' will not suffice:

<code bash>wpa_supplicant -B -i INTERFACE -c <(wpa_passphrase MYSSID PASSPHRASE)</code>

Find wireless interfaces with ''iw list''.

===== systemd-networkd =====

<file - /etc/systemd/network/INTERFACE.network>
[Match]
Name=INTERFACE

[Network]
DHCP=yes</file>
<file - /etc/wpa_supplicant/wpa_supplicant-INTERFACE.conf>
ctrl_interface=/var/run/wpa_supplicant
eapol_version=1
ap_scan=1
fast_reauth=1

network={
    ssid="MYSSID"
    psk="MYSUPERSECUREPASSWORD"
    priority=1
}
</file>
start that shit up:
<code bash>
systemctl enable systemd-networkd
systemctl enable wpa_supplicant@INTERFACE
systemctl start systemd-networkd
systemctl start wpa_supplicant@INTERFACE
</code>

===== Troubleshooting =====

==== I connected to the WLAN, but still can't access the network ====

Do you have an IP address? Check this with ''ip a''. If not, you have to obtain an IP via ''dhcpcd INTERFACE'' or set it manually with ''ip a add ADDRESS dev INTERFACE''.

Could be that your ''/etc/resolv.conf'' doesn't list any DNS servers. Either add this:
<file - /etc/resolv.conf>
nameserver 127.0.0.1
</file>
(replace ''127.0.0.1'' with the IP address of your router/DNS server)

or use ''systemd-resolved'':

<code bash>
mv /etc/resolv.conf /etc/resolv.conf.before-the-systemd-nation-attacked
systemctl enable --now systemd-resolved
</code>

systemd-resolved populates the ''/etc/resolv.conf'' with known DNS servers automagically, but you can still add them manually:
<file /etc/systemd/resolved.conf>
…
DNS=1.2.3.4
FallbackDNS=5.6.7.8
…
</file>