4.13. Probing Your Wireless Interface Card

Problem

Your wireless interface card came in a colorful box and wads of multilanguage documentation. But none of it gives you the technical specs that you really want, such as supported channels, encryption protocols, modes, frequencies—you know, the useful information.

Solution

Both wlanconfig, which is part of the MadWiFi driver package, and iwlist, which is part of wireless-tools, will probe your wireless card and tell you what it can do, like this command that displays what protocols the card supports:

	pyramid:~# wlanconfig ath0 list caps
	ath0=7782e40f<WEP,TKIP,AES,AES_CCM,HOSTAP,TXPMGT,SHSLOT,SHPREAMBLE,\
	TKIPMIC,WPA1,WPA2,WME>

This means this is a nice modern card that supports all of the important encryption and authentication protocols, and it can serve as an access point.

This command shows all of the channels and frequencies the card supports:

	pyramid:~# wlanconfig ath0 list chan

Find out what kind of keys your card supports:

	pyramid:~# iwlist ath0 key

Which card functions are configurable:

	pyramid:~# iwlist ath0 event

This particular card supports variable transmission power rates:

	pyramid:~# iwlist ath0 txpower

What bit-rates are supported?

	pyramidwrap:~# iwlist ath0 rate

The iwconfig command shows the card's current configuration:

	pyramidwrap:~# iwconfig ath0

Discussion

What does this output mean?

	ath0=7782e40f<WEP,TKIP,AES,AES_CCM,HOSTAP,TXPMGT,SHSLOT,SHPREAMBLE,\
	TKIPMIC,WPA1,WPA2,WME>

It means this particular card supports WEP encryption, Temporal Key Integrity Pro-tocol (TKIP), Advanced Encryption Standard with Counter Mode with CBC-MAC Protocol (AES and AES_CCM), can function as an Access Point, has variable transmission power, supports TKIP Message Identity Check, WPA/WPA2, frame bursting, and Wireless Media Extensions.

SHSLOT and SHPREAMBLE stand for "short slot" and "short preamble," which have to do with faster transmission speeds. Matthew Gast's 802.11 Wireless Networks: The Definitive Guide (O'Reilly) tells you all about these.

See Also