Wi-Fi Management

Overview

The Wi-Fi management API is used to manage Wi-Fi networks. It supports below modes:

  • IEEE802.11 Station (STA)

  • IEEE802.11 Access Point (AP)

Only personal mode security is supported with below types:

  • Open

  • WPA2-PSK

  • WPA2-PSK-256

  • WPA3-SAE

The Wi-Fi management API is implemented in the wifi_mgmt module as a part of the networking L2 stack. Currently, two types of Wi-Fi drivers are supported:

  • Networking or socket offloaded drivers

  • Native L2 Ethernet drivers

Compiled Features

To support applications that only require a certain subset of Wi-Fi features, CONFIG_WIFI_USAGE_MODE can be used as a hint for drivers to limit the functionality that needs to be compiled in. The following usage hints are available:

Note

Support for a requested usage mode is hardware dependent.

Wi-Fi PSA crypto supported build

To enable PSA crypto API supported Wi-Fi build, the CONFIG_WIFI_NM_WPA_SUPPLICANT_CRYPTO_ALT and the CONFIG_WIFI_NM_WPA_SUPPLICANT_CRYPTO_MBEDTLS_PSA need to be set.

Wi-Fi Enterprise test: X.509 Certificate management

Wi-Fi enterprise security requires use of X.509 certificates, two methods of installing certificates are supported:

Compile time certificates

Test certificates in PEM format are committed to the repo at samples/net/wifi/test_certs and the during the build process the certificates are converted to a C header file that is included by the Wi-Fi shell module.

If you want to use your own certificates, you can replace the existing certificates with your own certificates in the same directory.

$ export WIFI_TEST_CERTS_DIR=samples/net/wifi/test_certs/rsa3k
$ cp client.pem $WIFI_TEST_CERTS_DIR
$ cp client-key.pem $WIFI_TEST_CERTS_DIR
$ cp ca.pem $WIFI_TEST_CERTS_DIR
$ cp client2.pem $WIFI_TEST_CERTS_DIR
$ cp client-key2.pem $WIFI_TEST_CERTS_DIR
$ cp ca2.pem $WIFI_TEST_CERTS_DIR
$ west build -p -b <board> samples/net/wifi -S wifi-enterprise

or alternatively copy rsa2k certificates by changing the WIFI_TEST_CERTS_DIR environment variable.

$ export WIFI_TEST_CERTS_DIR=samples/net/wifi/test_certs/rsa2k

or you can set the WIFI_TEST_CERTS_DIR environment variable to point to the directory containing your certificates.

$ west build -p -b <board> samples/net/wifi -S wifi-enterprise -- -DWIFI_TEST_CERTS_DIR=<path_to_your_certificates>

Run time certificates

The Wi-Fi shell module uses TLS credentials subsystem to store and manage the certificates. The certificates can be added at runtime using the shell commands, see TLS Credentials Shell for more details. The sample or application need to enable the CONFIG_WIFI_SHELL_RUNTIME_CERTIFICATES option to use this feature.

To facilitate installation of the certificates, a helper script is provided, see below for usage.

$ ./scripts/utils/wifi_ent_cert_installer.py -p samples/net/wifi/test_certs/rsa2k

The script will install the certificates in the rsa2k directory to the TLS credentials store in the device over UART and using TLS credentials shell commands.

To initiate a Wi-Fi connection using enterprise security, use one of the following commands depending on the EAP method:

  • EAP-TLS

    uart:~$ wifi connect -s <SSID> -c <channel> -k 7 -w 2 -a <Anonymous identity> --key1-pwd <Password EAP phase1> --key2-pwd <Password EAP phase2>

  • EAP-TTLS-MSCHAPV2

    uart:~$ wifi connect -s <SSID> -c <channel> -k 14 -K <Private key Password> --eap-id1 <Client Identity> --eap-pwd1 <Client Password> -a <Anonymous identity>

  • EAP-PEAP-MSCHAPV2

    uart:~$ wifi connect -s <SSID> -c <channel> -k 12 -K <Private key Password> --eap-id1 <Client Identity> --eap-pwd1 <Client Password> -a <Anonymous identity>

Server certificate is also provided in the same directory for testing purposes. Any AAA server can be used for testing purposes, for example, FreeRADIUS or hostapd.

Certificate requirements for EAP methods

Different EAP methods have varying client-side certificate requirements, as outlined below:

  • EAP-TLS - Requires both a client certificate (and its private key) and a CA certificate on the client.

    The client authenticates itself to the server using its certificate.

  • EAP-TTLS-MSCHAPV2 - Requires only the CA certificate on the client.

    The client authenticates to the server using a username and password <MSCHAPV2> inside the TLS tunnel. No client certificate is needed.

  • EAP-PEAP-MSCHAPV2 - Requires only the CA certificate on the client.

    Like TTLS, the client uses a username and password <MSCHAPV2> inside the TLS tunnel and does not require a client certificate.

Note

The certificates are for testing purposes only and should not be used in production. They are generated using FreeRADIUS raddb scripts.

Note

When using TLS credentials subsystem, by default the volatile backend i.e., CONFIG_TLS_CREDENTIALS_BACKEND_VOLATILE is chosen. When using the volatile backend, the certificates are stored in RAM and are lost on reboot, so the certificates need to be installed again after reboot. As an alternative, the PS (protected storage) backend i.e., CONFIG_TLS_CREDENTIALS_BACKEND_PROTECTED_STORAGE can be used to store the certificates in the non-volatile storage.

How to Generate Test Certificates Using FreeRADIUS

The test certificates in samples/net/wifi/test_certs/rsa2k are generated using the FreeRADIUS raddb/certs scripts. You can generate your own certificates for testing as follows:

  1. Prerequisites - Install OpenSSL and GNU Make. - Download the FreeRADIUS raddb/certs directory.

  2. Edit the Makefile In the raddb/certs directory, edit the Makefile to add -nodes to the OpenSSL commands for server and client keys. This ensures the private keys are not password-protected (Zephyr Wi-Fi shell does not support private key passwords):

    $(OPENSSL) req -new -out server.csr -keyout server.key -nodes -config ./server.cnf
$(OPENSSL) req -new -out client.csr -keyout client.key -nodes -config ./client.cnf

  3. (Optional) Edit the .cnf files Customize server.cnf and client.cnf as needed for your environment.

  4. Generate Certificates Run the following commands in the raddb/certs directory:

    make destroycerts
make server
make client

  5. Rename Files for Zephyr Match the filenames used in Zephyr samples:

    FreeRADIUS Output

    Zephyr Sample Name

    ca.pem server.key server.pem client.key client.pem

    ca.pem server-key.pem server.pem client-key.pem client.pem

  6. Copy the files Place the renamed files in your Zephyr project’s certificate directory (e.g., samples/net/wifi/test_certs/rsa2k).

Note

These certificates are for testing only and should not be used in production.

API Reference

Wi-Fi Management

Related code samples

  • Wi-Fi AP-STA modeConfigure a Wi-Fi board to operate as both an Access Point (AP) and a Station (STA).