wpa_supplicant

From NixOS Wiki

General

wpa_supplicant can be enabled on NixOS with networking.wireless.enable = true.

Extra configuration can be specified inside networking.wireless.extraConfig.

wpa_supplicant_gui

To be able to use wpa_gui or wpa_cli as user put the following in your configuration.nix file: 

networking.wireless.userControlled.enable = true;

Also your user must be part of the wheel group (replace USER with your username): 

users.extraUsers.USER.extraGroups = [ "wheel" ];

Using wpa_supplicant from within the configuration file

You can configure your networks with the option networks. You have to fill the name(s) of your wifi(s) after the option and the preshared-key(s) (usually called psk). If you do not want to have your secret key in plaintext, you can use pskRaw, generated with wpa_passphrase SSID password. An example of using networks : 

networking.wireless.networks.Wifi_name.pskRaw = "pskRaw generated";

If you have multiple networks, and you want to set the priority, you can use networking.wireless.networks.Wifi_name.priority = <value>;

A full example to connect to a university or similar network that uses MSCHAPV2 (like UWF): 

  networking.wireless.networks."uwf-argo-air" = {
    hidden = true;
    auth = ''
      key_mgmt=WPA-EAP
      eap=PEAP
      phase2="auth=MSCHAPV2"
      identity="unx42"
      password="p@$$w0rd"
      '';
    };

To avoid having your network password in accessible plaintext on your system or in your version control consider using networking.wireless.environmentFile.

Another example of simple wpa2 auth: 

  networking.networkmanager.enable = false;
  networking.wireless = {
    enable = true;  # Enables wireless support via wpa_supplicant.
    networks."MYSSID".psk = "myPresharedKey";
    extraConfig = "ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=wheel";
    # output ends up in /run/wpa_supplicant/wpa_supplicant.conf
  };

Switching Network

From the shell terminal, use the wpa_cli command line tool and specify the network interface device with -g 

wpa_cli -g /run/wpa_supplicant/wlp3s0
list_network
select_network 2

As a means to debug if things are working, open another terminal and examine the logs by: 

$ journalctl -u wpa_supplicant -f

MAC spoofing

Since there is no option to randomize your MAC address for wpa supplicant, you can instead create your own service using GNU's macchanger: 

let
	change-mac = pkgs.writeShellScript "change-mac" ''
		card=$1
		tmp=$(mktemp)
		${pkgs.macchanger}/bin/macchanger "$card" -s | grep -oP "[a-zA-Z0-9]{2}:[a-zA-Z0-9]{2}:[^ ]*" > "$tmp"
		mac1=$(cat "$tmp" | head -n 1)
		mac2=$(cat "$tmp" | tail -n 1)
		if [ "$mac1" = "$mac2" ]; then
			if [ "$(cat /sys/class/net/"$card"/operstate)" = "up" ]; then
				${pkgs.iproute2}/bin/ip link set "$card" down &&
				${pkgs.macchanger}/bin/macchanger -r "$card"
				${pkgs.iproute2}/bin/ip link set "$card" up
			else
				${pkgs.macchanger}/bin/macchanger -r "$card"
			fi
		fi
	'';
in
	systemd.services.macchanger = {
		enable = true;
		description = "macchanger on wlan0";
		wants = [ "network-pre.target" ];
		before = [ "network-pre.target" ];
		bindsTo = [ "sys-subsystem-net-devices-wlan0.device" ];
		after = [ "sys-subsystem-net-devices-wlan0.device" ];
		wantedBy = [ "multi-user.target" ];
		serviceConfig = {
			Type = "oneshot";
			ExecStart = "${change-mac} wlan0";
		};
	};

Where you need to change the wlan0 with your own wifi network interface. You can list your interfaces by running ip link, your wifi network interface should have "wl" prepended. Note that the above snippet fully randomizes your MAC address, for more information you can read macchanger's manpage. This obviously requires you to have the macchanger package installed.

Eduroam

Nowadays, using EAP-PWD is preferred over MSCHAPv2 when connecting to eduroam or other institutional networks. It provides stronger security claims and is simpler to set up. It also never transmits your password, doesn't require certificates and needs less authentication roundtrips. The identity and password should be given to you by your institution. 

 networking.wireless.networks.eduroam = {
   auth = ''
     key_mgmt=WPA-EAP
     eap=PWD
     identity="youruser@yourinstitution.edu"
     password="p@$$w0rd"
   '';
 };

WEP support

You may encounter a situation where you are in a hotel, for example, and the WiFi uses WEP encryption. As of version 2.10 of wpa_supplicant, WEP support is not enabled by default. To enable it, add the following to your configuration.nix: 

  nixpkgs.overlays = [
    (self: super: {
      wpa_supplicant = super.wpa_supplicant.overrideAttrs (oldAttrs: rec {
        extraConfig = oldAttrs.extraConfig + ''
	      CONFIG_WEP=y
	    '';
      });
    })
  ];

This builds wpa_supplicant with WEP support.

Fixing "legacy sigalg disallowed or unsupported"

When connecting to an institutional network fails, and something similar to following lines appear in the system log: 

mrt 31 17:17:19 t14 wpa_supplicant[727029]: SSL: SSL3 alert: write (local SSL3 detected an error):fatal:internal error
mrt 31 17:17:19 t14 wpa_supplicant[727029]: OpenSSL: openssl_handshake - SSL_connect error:0A00014D:SSL routines::legacy sigalg disallowed or unsupported

The cause is probably an outdated RADIUS server that uses an old (insecure) signature algorithm. A workaround can be to reduce OpenSSL's security setting to allow insecure ciphers. Add the following to your NixOS configuration: 

networking.wireless.extraConfig = ''
  openssl_ciphers=DEFAULT@SECLEVEL=0
'';

External links

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