How to use the command `wpa_cli` (with examples)

The wpa_cli command is a command-line tool that provides an interface to interact with the wpa_supplicant, which is a software application responsible for implementing wireless protocols, such as WPA (Wi-Fi Protected Access). This command allows users to perform various actions related to wireless network management including scanning for available networks, adding new network interfaces, configuring network settings, and saving configurations. This makes it an essential tool for network administrators and users who need to manage Wi-Fi connections via the command line.

Use case 1: Scanning for Available Networks

Code:

wpa_cli scan

Motivation:

Scanning for available networks is often the first step when connecting to a new wireless network. It allows users to see which Wi-Fi networks are in range and decide which one to connect to. For network administrators, scanning is crucial for diagnosing network coverage and interference issues.

Explanation:

• wpa_cli: This is the command-line tool that interfaces with the wpa_supplicant.
• scan: This argument tells wpa_cli to initiate a scan for available wireless networks. The scan gathers information about all the networks that are within range of the Wi-Fi adapter.

Example output:

OK

When you execute the wpa_cli scan command, it will typically return “OK” to indicate that the scan process has been initiated successfully. The results can then be viewed after the scanning completes.

Use case 2: Showing Scan Results

Code:

wpa_cli scan_results

Motivation:

After performing a network scan, viewing the scan results is necessary to obtain information about the available networks, such as their SSIDs, signal strength, and security protocols. This information aids in selecting the best network to connect to based on signal quality and security.

Explanation:

• wpa_cli: Command-line tool for wireless network management.
• scan_results: This argument requests the results from the last network scan, listing all detected wireless networks along with relevant details such as the BSSID, frequency, signal level, flags, and SSID.

Example output:

bssid / frequency / signal level / flags / ssid
12:34:56:78:9a:bc	2412	-50	[WPA2-PSK-CCMP][ESS]	MyNetwork
21:43:65:87:9b:dc	2462	-70	[WEP][ESS]	OtherNetwork

The output provides a list of networks, where each entry contains the BSSID (unique identifier of the access point), frequency, signal strength, security flags, and SSID.

Use case 3: Adding a Network

Code:

wpa_cli add_network 0

Motivation:

Adding a network is essential when you want to establish a new configuration for a Wi-Fi connection. It allows users to prepare the configuration before setting detailed parameters like SSID, security settings, and more. This step sets the groundwork for associating with a specific network.

Explanation:

• wpa_cli: The tool used to configure wireless settings.
• add_network: This command option is used to create a new network entry in the wpa_supplicant configuration.
• 0: The network ID, which is a number assigned to this new network. When you create a network, it usually starts with zero and increments with each new addition.

Example output:

0

The output represents the network ID assigned to the newly added network. This ID is later used in other commands to reference and modify this specific network configuration.

Use case 4: Setting a Network’s SSID

Code:

wpa_cli set_network 0 ssid "MyNetwork"

Motivation:

Setting the SSID (Service Set Identifier) for a network is crucial because it specifies which Wi-Fi network to connect to. The SSID is the name that is broadcast by the router, and users need to configure it correctly to ensure they can connect to the desired network.

Explanation:

• wpa_cli: Interface for configuring network settings.
• set_network: Command to modify the attributes of a specified network.
• 0: The network ID referring to the specific network you want to configure.
• ssid: The parameter that specifies the network name.
• "MyNetwork": The actual SSID or network name for which the settings are being applied. It should match the SSID broadcast by the wireless network.

Example output:

OK

An “OK” message indicates that the SSID has been set successfully for the specified network ID.

Use case 5: Enabling a Network

Code:

wpa_cli enable_network 0

Motivation:

Enabling a network is a crucial step to make your wireless device attempt to connect to the specified Wi-Fi network using the provided settings. This is often done after correctly setting all necessary parameters like SSID and security credentials.

Explanation:

• wpa_cli: The command-line tool for network configuration.
• enable_network: This command enables the specific network configuration, allowing the system to attempt connectivity.
• 0: The network ID associated with the network you wish to enable.

Example output:

OK

The “OK” response indicates that the network has been successfully enabled and the system is ready to connect to it.

Use case 6: Saving Configuration

Code:

wpa_cli save_config

Motivation:

After configuring a network, it is important to save the changes to the wpa_supplicant’s configuration file to ensure that the settings persist across reboots. This prevents the need to reconfigure the network each time the system restarts.

Explanation:

• wpa_cli: Tool for invoking commands to manage network connections.
• save_config: This command saves the current network configuration settings to the wpa_supplicant configuration file. It ensures that any changes made, such as added networks or altered network properties, are written to disk.

Example output:

OK

The “OK” response indicates that the current configurations have been successfully saved to the wpa_supplicant’s configuration file.

Conclusion:

The wpa_cli command is a powerful utility for managing wireless connections via the command line. It allows users to perform essential tasks such as scanning for networks, configuring network settings, enabling networks for connection, and saving configurations for future use. By understanding and utilizing the examples provided, users can effectively manage their wireless networking needs in various environments.