` gets replaced with the actual SSID
+ once devices connect. On the bottom you will see devices asking for specific
+ SSID.
+
+- This could be sped up by exploiting WiFi vulnerabilities, but that would no
+ longer be in the white hat territory and thus I don't concern myself with it.
+
+### Returning to normalcy
+
+1. Exit `airodump-ng` by `CTRL - C` as usual.
+1. Exit monitoring mode through `airmon-ng stop wlan0phy`
+1. Restart your network management (the `airmon-ng start wlan0` and
+ `airmon-ng check-kill` probably gave you a hint), for me it's
+ `systemctl restart iwd NetworkManager`, while `wpa_supplicant` would be more
+ common.
+
+### TODO
+
+_I should investigate and write about these:_
+
+- `man airodump-ng` may have nice flags as currently nothing is stored.
+ - Security people should have some data to compare to on what is normal in the
+ network environment and when changes happen. Then again with less data
+ stored, there is less chance of doing something illegal by accident, while I
+ think the passive listening this page focuses on is the same as VHF scan all
+ button.
+- I think `kismet` does the same as `airodump-ng`, while it may be more focused
+ on [wardriving](https://en.m.wikipedia.org/wiki/Wardriving).
+
+## QR codes for hidden SSIDs
+
+[zxing](https://github.com/zxing/zxing/wiki/Barcode-Contents#wi-fi-network-config-android-ios-11)
+and [Wikipedia](https://en.wikipedia.org/wiki/Wi-Fi#Securing_methods) agree on
+`WIFI:T:WPA;S:mynetwork;P:mypass;;` so my wondering would be:
+`WIFI:T:nopass;S:openwireless.org;;H:true;` where only `P:mypass` got omitted.
+
+
+# The capital H is the highest error correction, others are LMQ
+% qrencode -l H -t utf8 "WIFI:T:nopass;S:openwireless.org;;H:true;"
+█████████████████████████████████████
+█████████████████████████████████████
+████ ▄▄▄▄▄ █▀ █▀▀▀▀ ▀▄▄▀█ ▄▄▄▄▄ ████
+████ █ █ █▀ ▄ █▀▄▀▄█▄▄ █ █ █ ████
+████ █▄▄▄█ █▀█ █▄▀▀█▀▀█▀██ █▄▄▄█ ████
+████▄▄▄▄▄▄▄█▄█▄█ █ █▄▀ ▀ █▄▄▄▄▄▄▄████
+████ ▄ █▄ ▄ ▄█▄█ ██▀▀ ▄▀▄▀ █▄▀████
+█████ █▄▀▄▄ ▀ ▄▄▄▀▀▄▀▀ ▄▀ ▀▀▄█ ████
+████ ▀▄█▄█▄▄█▄▀▄▀█ ▄▄██▀▀▄ ▄▀▀ ████
+████▄▄█▀ ▀▄ ▀ ▄█▀ ▀█▄▄█ ▀██ ▀▀███████
+████▀ ▀▀▄▄ █ █▄▄▀▄▄▄▄█ ▄▀▄ ██▀▀████
+████ █▄█ ▄▄█▄▀█ ▄███▄▄█▀▀▄▀▀▀█▄▄▀████
+████▄█▄██▄▄█ ▄▄▄▀▀█▄ ▄▄█ ▄▄▄ ▀▄▄▄████
+████ ▄▄▄▄▄ █▄▀▄█▀ ▄▄▀ █ █▄█ ▀ █ ████
+████ █ █ █ ███▄█▄▄█▄▀▀ ▄ ▀▄ █████
+████ █▄▄▄█ █ ▄ ▄█▀▄ ▀ ▀▄▄▀▄▀ ▀████
+████▄▄▄▄▄▄▄█▄▄▄▄███▄▄▄█▄▄▄▄▄▄▄▄▄█████
+█████████████████████████████████████
+█████████████████████████████████████
+
+
+_While the above looks messy in my `jekyll serve -l`,
+[Binary Eye](https://github.com/markusfisch/BinaryEye) detected it regardless._
diff --git a/n/nomap.md b/n/nomap.md
index 46c9b20..53c8a14 100644
--- a/n/nomap.md
+++ b/n/nomap.md
@@ -32,6 +32,9 @@ Microsoft has a separate
[location services opt-out](https://account.microsoft.com/privacy/location-services-opt-out)
which uses MAC addresses instead.
+**_Hidden SSID won't work for opt-out in some of those services. Refer to
+[n/hiddenssid](hiddenssid.html)._**
+