Iwconfig is similar to ifconfig(8), but is dedicated to the wireless interfaces. It is used to set the parameters of the network interface which are specific to the wireless operation (for example : the frequency). Iwconfig may also be used to display those parameters, and the wireless statistics (extracted from /proc/net/wireless).
All these parameters and statistics are device dependent. Each driver will provide only some of them depending on hardware support, and the range of values may change. Please refer to the man page of each device for details.
For each device which supports wireless extensions, iwconfig will display the name of the MAC protocol used (name of device for proprietary protocols), the ESSID (Network Name), the NWID, the frequency (or channel), the sensitivity, the mode of operation, the Access Point address, the bit-rate, the RTS threshold, the fragmentation threshold, the encryption key and the power management settings (depending on availability).
The parameters displayed have the same meaning and values as the parameters you can set, please refer to the previous part for a detailed explanation of them. Some parameters are only displayed in short/abbreviated form (such as encryption). You may use iwlist(8) to get all the details. Some parameters have two modes (such as bitrate). If the value is prefixed by `=', it means that the parameter is fixed and forced to that value, if it is prefixed by `:', the parameter is in automatic mode and the current value is shown (and may change).
- Access Point/Cell
- An address equal to 00:00:00:00:00:00 means that the card failed to associate with an Access Point (most likely a configuration issue). The Access Point parameter will be shown as Cell in ad-hoc mode (for obvious reasons), but otherwise works the same.
If /proc/net/wireless exists, iwconfig will also display its content. Note that those values will depend on the driver and the hardware specifics, so you need to refer to your driver documentation for proper interpretation of those values.
- Link quality
- Overall quality of the link. May be based on the level of contention or interference, the bit or frame error rate, how good the received signal is, some timing synchronisation, or other hardware metric. This is an aggregate value, and depends totally on the driver and hardware.
- Signal level
- Received signal strength (RSSI - how strong the received signal is). May be arbitrary units or dBm, iwconfig uses driver meta information to interpret the raw value given by /proc/net/wireless and display the proper unit or maximum value (using 8 bit arithmetic). In Ad-Hoc mode, this may be undefined and you should use iwspy.
- Noise level
- Background noise level (when no packet is transmitted). Similar comments as for Signal level.
- Rx invalid nwid
- Number of packets received with a different NWID or ESSID. Used to detect configuration problems or adjacent network existence (on the same frequency).
- Rx invalid crypt
- Number of packets that the hardware was unable to decrypt. This can be used to detect invalid encryption settings.
- Rx invalid frag
- Number of packets for which the hardware was not able to properly re-assemble the link layer fragments (most likely one was missing).
- Tx excessive retries
- Number of packets that the hardware failed to deliver. Most MAC protocols will retry the packet a number of times before giving up.
- Invalid misc
- Other packets lost in relation with specific wireless operations.
- Missed beacon
- Number of periodic beacons from the Cell or the Access Point we have missed. Beacons are sent at regular intervals to maintain the cell coordination, failure to receive them usually indicates that the card is out of range.
ifconfig(8), iwspy(8), iwlist(8), iwevent(8), iwpriv(8), wireless(7).