About three years ago I released a Python program to send out WiFi beacon frames with an AirPCap adapter. During my last holiday, I took some time to add a new feature to apc-b.py: option nomap.
When you start apc-b.py with option nomap, it first listens for 60 seconds and records all ESSIDs in finds in beacon frames. Then it starts to broadcast beacon frames for these ESSIDs, but with string _nomap appended to each ESSID.
apc-b_v0_2_0.zip (https)
MD5: 849DE418A1F325B9DC133DBE2E7CC501
SHA256: C3F28DCEFE6FF747780E384E49BB4D373BC983518C592E1BB18E8455F78E7F95
Didier Stevens 
Hello Didier! Can you explain what’s the use of such a feature?
Comment by akismet-ecee35bd5895ac49b688e3998a0c95c3 — Wednesday 20 June 2012 @ 13:09
The AirPcap is a great tool for experimenting with monitor mode RX and TX, but why is this _nomap option useful? What are you using it for? Thanks!
-Josh
Comment by Joshua Wright — Wednesday 20 June 2012 @ 13:52
i had an idea of flooding the area with fake SSIDs and keep refreshing them so they don’t disappear ..
is that possible?
Comment by مصطفى (@5yn74x) — Wednesday 20 June 2012 @ 13:57
@vos @Josh Sorry I wasn’t more explicit, I assumed people would remember that _nomap is what Google proposes to append to your ESSID to opt out of their WiFi sniffing operation (Streetview car).
So this feature is my tongue-in-cheek way of telling Google we all want to opt out 😉
Comment by Didier Stevens — Wednesday 20 June 2012 @ 14:01
@مصطفى (@5yn74x) That is exactly what my program does.
Comment by Didier Stevens — Wednesday 20 June 2012 @ 14:02
can’t you just create random SSIDs? i don’t know much but what is ESSID for?
Comment by مصطفى (@5yn74x) — Wednesday 20 June 2012 @ 17:01
Yes I can. In infrastructure mode, the SSID is the ESSID.
Comment by Didier Stevens — Wednesday 20 June 2012 @ 17:45
thanks sir, i really got a lot of basics to learn ^^
Comment by مصطفى (@5yn74x) — Wednesday 20 June 2012 @ 19:32
Excellent Didier, thank you. Should have recognized the _nomap, here I was thinking it had something to do with mmap(). My bad.
-Josh
Comment by Joshua Wright — Wednesday 20 June 2012 @ 23:49