Is Network traffic monitoring with WireShark:
Active Monitoring
Passive Monitoring
Combinational Monitoring
Wireshark performs passive monitoring. It would likely help you to know what the differences are.
Passive monitoring indicates that a network device has been put into promiscuous mode and begins collecting network frames as they pass by, making them available for analysis.
Active monitoring indicates that some sort of stimulation is generated by the tool performing the monitoring. An example would be broadcasting out a large number of SSIDs to attempt to stimulate a response from a wireless network device.
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Description - How I can get the number of BLE connection in iOS.
I want to restrict a user to add more BLE sensor after a particular number of BLE connection. I want to get the number of a BLE connection a device can handle.
A connection represents state, not traffic. The count of connections will be bound by either memory or the data structures used by the Bluetooth stack to manage them, both unknown. My answer is, "As many as it can and no more."
Packets represent traffic and each is handled one at a time. From this perspective, my answer is, "One."
However, if a packet cannot be processed out of the critical paths in the chip and protocol stack fast enough to begin processing the next packet, packets can be dropped. Experience has shown these critical paths in iOS are dependent on the traffic's packet size and rate. Additionally, other devices in the area not connected to your BLE stack may be flooding the radio spectrum and causing packet collisions outside the stack. I have seen BLE traffic go to hell with an excess of 20 connections and as few as one. From this perspective my answer is, "It depends."
I have been messing around with monitoring probe requests to track wi-fi enabled devices. I have a scanner in a set location that I know rarely has people near it 24-7. When I look at the resulting probe requests, it appears that some wifi enabled devices are around almost 24-7, which makes me think this is not really a person with a smartphone.
If there are APs in the area, is it possible I am picking up something from them? I am only collecting probe requests: type 0 (management) subtype 4 (probe request). As far as I can tell, only clients should send probe requests.
Usually the client (also called station node) keep sending probe requests to scan available APs in it's range. AP will respond with probe response and also it keep sending beacons. But an AP can also send probe requests, if it happens to scan for other APs. You can check the probe requests captured and see the RSSI field(signal strength). RSSI being low indicates the sender is a bit far from your monitor.
If probe response packets announces the capabilities of a network,
then what is the purpose of Beacon frames in wireless 802.11 ?
Among other things, beacons allow a device to passively scan all channels for available Access Points so that a list may be presented to a user showing signal strength. They also allow a device to detect if there is another Access Point on the same network and presumably on a different channel with a better signal.
My understanding is that current WiFi driver uses rate control algorithm to choose a data rate within a small set of predetermined values to send packets over the WiFi medium. Different algorithms exist for this purpose. But how does this process work when WiFi driver decides that the connection is lost and shutdown the connection all together? Which part of the code should I read in open source WiFi driver such as MadWiFi and the likes?
The WiFi driver for your hardware which runs in Linux communicates with the WiFi chip which also runs a pretty complex firmware. The interface between the driver and the firmware is hardware specific. In some hardware the detection of connection loss events is done completely by the firmware and the driver only gets a "disconnected" event while in others the driver is also involved.
Regardless of who does what disconnection usually occurs due to either
Receiving a DEAUTH frame from the AP
Detecting too many missing beacons. Beacons are WiFi frames sent periodically by the AO (for most APs every ~100ms) . If you get too far from the AP or the AP was just powered off you stop seeing the beacons in the air and usually you'll signal disconnection or try to roam to a different AP.
Too many failures on Tx of packets (i.e. not receiving ACK frames for too much traffic)
This usually indicates that you've gone too far from the AP. It could be that you can "hear" the AP but it can't hear you already. In this case it also makes sense to signal a disconnection.
For example you can look in TI wifi driver in the Linux kernel drivers/net/wireless/ti/wlcore/events.c and the function wlcore_event_beacon_loss()
In Cfg80211 architecture, assume we are station mode.
driver call kernel API cfg80211_send_disassoc() if we received a deassoc/deauth frame.this function will notify corresponding application (ex wpa_supplicant) a disconnect event.
on another hand, when we decide to disconnect with AP, applicantion (ex wpa_supplicant) can call linux kernel API cfg80211_disconnected(), it will trigger corresponding driver ioctl function to finish disconnection task.
For a GPS tracking app, recording location signals with WIFI turned on results in really imprecise data or data with gaps.
I've used the Reachability queries to detect if wifi is available prior to starting tracking. The problem is that if when that query is made the wifi is enabled but not connected to a network, it shows that the internet is not reachable via wifi, but that's not an indication of if the setting is disabled in the settings app. This means that if the user starts running and a connection is made mid-run, they'll get a location signal from the wifi instead of the GPS or cell network. Consequently the accuracy on those data points can be > 10 meters so I want to skip that point. The issue is that on wifi they'll have a large blank period where their signal wasn't recorded.
So how can I check if wifi is enabled but disconnected?
I've read all the other reachability discussions I could find but this seems to be the one gap with lots of responses incorrectly suggesting that reachability solves this out of the box.
...and I'm not going to require wifi - just alert them to the fact that it is enabled so at some point in their workout their location data might be lost (due to inaccuracy).
It's been quite a while since you asked, but I just came across this one.
It doesn't look like there is any way to do it if you want to obey Apple's rules. sysctl and ioctl won't work because there are no flags which will show you wether WiFi is enabled. For example the flags for "UP" and "RUNNING" will be the same if WiFi is disabled or WiFi is enabled but not connected.
Apple's own WiFi framework uses mach to directly communicate with the kernel and I doubt Apple would allows such code in the AppStore.
This IS possible, but the solution is obscure and ugly. The short answer is that if you see TWO interfaces with the name "awdl0" then WiFi is enabled, just one and it's disabled.
See Better way to detect WiFi enabled/disabled on iOS? for a more complete description and sample code.