However, because an 802.11a/b/g device cannot tell that a Greenfield device is transmitting, it will go right ahead and transmit.

Normally, 802.11 devices share channels by sensing when another device is transmitting, using a back-off timer to wait until the channel is free. Instead, their transmissions are likely to collide, causing errors and retransmissions for both parties.

802.11a/b/g devices cannot communicate with a Greenfield AP.

You can then feed this file into your favorite network analyzer such as Wireshark to examine the traffic offline.Ī device that uses 802.11n high throughput (HT) mode - also known as Greenfield mode - assumes that there are no 802.11a/b/g stations using the same channel. This creates a file called airportSniffXXXXXX.cap in the /tmp directory, where XXXXXX is a string for uniqueness. You need to be an administrator (i.e., you need sudo privileges) to do this: Tell airport to sniff, and optionally provide a channel (which you now know thanks to your ability to scan). More awesome, perhaps, is the tool's ability to actually perform traffic sniffing and capture packets. $ airport en1 scan SSID BSSID RSSI CHANNEL HT CC SECURITY (auth/unicast/group) moscohome 00:22:6b:8b:86:51 -61 10 N - WPA2(PSK/AES/AES) PUBLIC-455H 00:15:6d:60:95:d1 -82 1 N - NONE Alex Network 00:1e:e5:24:c4:4f -86 1 Y TW WPA(PSK/TKIP,AES/TKIP) WPA2(PSK/TKIP,AES/TKIP) linksysELNIDO 00:21:29:a3:fd:99 -90 6 N - WPA(PSK/AES,TKIP/TKIP) WPA2(PSK/AES,TKIP/TKIP) 2WIRE024 00:18:3f:02:2f:49 -88 6 N US WEP 2WIRE940 00:12:88:d9:85:41 -93 6 N US WEPIf I wanted to see which of my neighbors still haven't upgraded from WEP, I could just filter using grep:

Wireless network sniffer mac