Understanding the `iw` Command for Wireless Management (with examples)

The iw command is a powerful tool used in Linux environments for managing and manipulating wireless devices and configurations. It forms a part of the wireless-tools package and provides functionalities for interacting with Wi-Fi interfaces, including scanning for available networks, connecting, disconnecting, and querying information about the wireless setup. These functions are essential for network diagnostics, setup, and management from the command line.

Use case 1: Scan for available wireless networks

Code:

iw dev wlp scan

Motivation:
Scanning for available wireless networks is a crucial step when you want to access a new Wi-Fi network or troubleshoot connectivity issues. It helps identify the available networks within range and provides essential details such as signal strength, network name (SSID), and encryption type.

Explanation:

• iw: This is the base command used to interact with wireless devices.
• dev wlp: Specifies the wireless device or network interface you want to interact with. Replace ‘wlp’ with your actual network interface name.
• scan: The operation instructs iw to scan for nearby wireless networks.

Example Output:

BSS 00:14:22:01:23:45(on wlp) -- associated
    SSID: HomeNetwork
    signal: -40 dBm
BSS 00:14:22:11:22:33(on wlp) -- not associated
    SSID: CoffeeShopWiFi
    signal: -60 dBm

Use case 2: Join an open wireless network

Code:

iw dev wlp connect SSID

Motivation:
Joining a wireless network is a fundamental operation when you need internet connectivity or access to network resources. This command allows you to connect to a specified open wireless network.

Explanation:

• iw: Base command for wireless configuration.
• dev wlp: Specifies the particular wireless device interface.
• connect: This argument directs iw to initiate a connection to the specified network.
• SSID: Replace this with the name of the wireless network you wish to connect to.

Example Output:

Connected to SSID "OpenNetwork"

Use case 3: Close the current connection

Code:

iw dev wlp disconnect

Motivation:
Disconnecting from a network is necessary when you want to prevent your device from accessing a particular Wi-Fi network or if you are troubleshooting internet issues.

Explanation:

• iw: The base command used for wireless configurations.
• dev wlp: Indicates the wireless interface in use.
• disconnect: Command to sever the current wireless network connection.

Example Output:

Disconnected from network

Use case 4: Show information about the current connection

Code:

iw dev wlp link

Motivation:
Viewing connection details is vital for network management and troubleshooting, providing a snapshot of current network-specific data such as SSID, signal strength, frequency, and other parameters.

Explanation:

• iw: The command base for interacting with wireless networks.
• dev wlp: Specifies which device’s connection status to examine.
• link: Command to display the status of the current wireless connection.

Example Output:

Connected to SSID "WorkNetwork"
Signal Strength: -50 dBm
Frequency: 2412 MHz

Use case 5: List all physical and logical wireless network interfaces

Code:

iw dev

Motivation:
Identifying all wireless interfaces is crucial when configuring network settings or troubleshooting, as it allows you to pinpoint which interfaces are active and which ones you need to configure.

Explanation:

• iw: Command base for wireless operations.
• dev: Instructs the command to output all available network interfaces, both logical and physical.

Example Output:

Interface wlp
    Type: managed

Use case 6: List all wireless capabilities for all physical hardware interfaces

Code:

iw phy

Motivation:
Understanding the capabilities of a wireless device is necessary for optimizing network performance. It includes details like supported frequencies and transmission powers, influencing what networks can be accessed and the conditions of those connections.

Explanation:

• iw: Command for interacting with wireless devices.
• phy: This argument requests the capabilities of each physical network interface.

Example Output:

Wiphy phy0
    Supported Frequencies:
        * 2412 MHz
        * 2437 MHz

Use case 7: List the kernel’s current wireless regulatory domain information

Code:

iw reg get

Motivation:
The regulatory domain dictates permissible frequencies and transmission power levels for your wireless device according to regional regulations. This information is vital for ensuring compliance and optimizing wireless performance.

Explanation:

• iw: The command base.
• reg get: Retrieves the current regulatory information according to the kernel.

Example Output:

country US: DFS-FCC
    (2402 - 2472 @ 40), (N/A, 30)

Use case 8: Display help for all commands

Code:

iw help

Motivation:
Consulting the help documentation is essential for users wishing to familiarize themselves with the full array of commands and utilities offered by iw. It serves as a key resource for learning and troubleshooting.

Explanation:

• iw: Base command for wireless management.
• help: Instructs iw to display a comprehensive list of available operations and options.

Example Output:

Usage:  iw [options] command
Commands:
    dev - interface manipulations and queries
    phy - hardware capabilities
    ...

Conclusion:

The iw command is an integral part of Linux network management, enabling users to scan, connect, disconnect, and view information about wireless networks. Each use case presented highlights a specific aspect of iw’s functionality, demonstrating its versatility and importance for users needing to manage wireless connectivity from the command line. By following the examples and motivation presented, users can efficiently leverage iw for diverse wireless network configurations and diagnostics.