iw

iw is a command-line tool used for configuring and managing wireless devices in Linux. It supports the modern nl80211 interface and is intended to replace older tools like iwconfig. The iw command provides more advanced and detailed control over wireless interfaces and supports the latest features of wireless hardware.

Basic Usage

To use iw, you typically need root privileges. The general syntax of the iw command is:

iw [OPTIONS] COMMAND [COMMAND_OPTIONS]

Common Commands and Options

1. List Devices

   • List all wireless devices:

     iw dev

   • Example output:

     phy#0
        Interface wlan0
            ifindex 3
            wdev 0x1
            addr 00:11:22:33:44:55
            type managed
            txpower 20.00 dBm

2. Link Status

   • Show information about the current link:

     iw dev wlan0 link

   • Example output:

     Connected to 00:11:22:33:44:55 (on wlan0)
     SSID: MyNetwork
     freq: 2412
     RX: 1234567 bytes (2345 packets)
     TX: 987654 bytes (3456 packets)
     signal: -40 dBm
     tx bitrate: 54.0 MBit/s

3. Scan for Networks

   • Scan for available wireless networks:

     iw dev wlan0 scan

   • Example output:

     BSS 00:11:22:33:44:55(on wlan0)
        TSF: 123456789012 usec (0d, 12:34:56)
        freq: 2412
        beacon interval: 100 TUs
        capability: ESS (0x0421)
        signal: -40 dBm
        last seen: 50 ms ago
        SSID: MyNetwork
        Supported rates: 1.0 2.0 5.5 11.0 22.0 36.0 48.0 54.0
        DS Parameter set: channel 1
        RSN:     * Version: 1
                * Group cipher: CCMP
                * Pairwise ciphers: CCMP
                * Authentication suites: PSK
                * Capabilities: 16-PTKSA-RC 1-GTKSA-RC (0x0000)

4. Set Interface Down

   • Bring a wireless interface down:

     iw dev wlan0 set type managed

   • Example:

     ip link set wlan0 down

5. Set Interface Up

   • Bring a wireless interface up:

     iw dev wlan0 set type managed

   • Example:

     ip link set wlan0 up

6. Join a Network

   • Connect to a wireless network (requires WPA supplicant for encrypted networks):

     iw dev wlan0 connect MyNetwork

   • For encrypted networks, additional configuration with WPA supplicant or network manager is needed.

7. Disconnect from a Network

   • Disconnect from the current network:

     iw dev wlan0 disconnect

8. Set Wireless Power Save Mode

   • Enable power save mode:

     iw dev wlan0 set power_save on

   • Disable power save mode:

     iw dev wlan0 set power_save off

9. Show Station Information

   • Show information about connected stations (for access points):

     iw dev wlan0 station dump

10. Change Wireless Interface Type

    • Change the type of a wireless interface (e.g., from managed to monitor):

      iw dev wlan0 set type monitor

Example Configuration Workflow

1. List Available Wireless Interfaces

   iw dev

2. Bring the Interface Down

   ip link set wlan0 down

3. Set Interface Type

   iw dev wlan0 set type managed

4. Bring the Interface Up

   ip link set wlan0 up

5. Scan for Available Networks

   iw dev wlan0 scan

6. Connect to a Network

   iw dev wlan0 connect MyNetwork

Conclusion

The iw tool is a powerful utility for managing and configuring wireless devices in Linux. It provides comprehensive control over wireless interfaces and supports advanced features. By mastering iw, administrators can effectively manage wireless connectivity and troubleshoot issues.