Simple direct advertising

RE: Simple direct advertising

Petter Myhre — Wed, 16 Nov 2016 11:46:37 GMT

I wasn't sure if hcitool lescan would show the directed advertisments, but I tested it, and it seems it does.

Where are you calling sd_ble_gap_adv_start()? And are you sure that it doesn't return any error code?

RE: Simple direct advertising

clementfumey — Mon, 14 Nov 2016 07:16:09 GMT

@Petter, Yes I am using a RPi3 with onboard bluetooth and hcitool lescan.

RE: Simple direct advertising

Petter Myhre — Fri, 11 Nov 2016 10:00:37 GMT

Ok. And you are using a RPi with a Bluetooth dongle to test? With hcitool lescan?

RE: Simple direct advertising

Roger Clark — Thu, 10 Nov 2016 22:30:50 GMT

Are you sure that a BLE device is ideal for your application?

Are you eventually connecting via a smartphone or via some custom hardware.

If its all custom hardware there may be other devices that better suit your need e.g. nRF24 series

www.nordicsemi.com/.../2.4GHz-RF

RE: Simple direct advertising

clementfumey — Thu, 10 Nov 2016 16:18:31 GMT

I don't want to connect to a central. The central just scan for advertisement and take decision weither or not a peripheral is advertising or not. There is no other ble exchance the only information I want is : Is this beacon advertising or not?. I want to use low duty cycle directed advertisement(but put high duty cycle here in the example for the sake of simplicity) to avoid people with a smartphone to see this advertisements.

RE: Simple direct advertising

Petter Myhre — Thu, 10 Nov 2016 11:02:28 GMT

@clementfumey Why do you want to hide the advertisment? If you only want to connect to a certain central, and you know its device address/IRK you can use whitelist to filter out connection requests from all other centrals.

RE: Simple direct advertising

Petter Myhre — Thu, 10 Nov 2016 11:00:12 GMT

@"Roger Clark", I assume that iOS and Android are not able to, other BLE devices are able as long as the firmware has access to radio/link layer.

RE: Simple direct advertising

Roger Clark — Thu, 10 Nov 2016 10:42:54 GMT

Petter

Can android or iOS behave as "curious" centrals. Perhaps iOS would not, but I'm not sure about android, or perhaps BLE devices like the CC2541 or CSR devices etc ,may have modes to be "curious" ??

RE: Simple direct advertising

Petter Myhre — Thu, 10 Nov 2016 10:12:04 GMT

I see you have set the interval to 0, which means you are enabling directed advertising with high duty cycle, this shall per spec only last for 1.28 s, then maybe you start the "normal" advertising when you get the advertising timeout event? See this for more information.

Yes, centrals should ignore directed advertisments that is not destined for them, but "curious" centrals wouldn't care about this.

RE: Simple direct advertising

Roger Clark — Wed, 09 Nov 2016 19:25:54 GMT

Very interesting,

This sort of question has been asked before.

devzone.nordicsemi.com/.../

The answer does not say if its possible to hide the advertising

Also see this link , it mentions directed advertising, but it doesnt say its hidden

blog.bluetooth.com/.../

I would interested to hear an official response to this security question, because DDOS of BLE devices could become a serious problem with the advert of the Web BLE API as browsers will be able to mount DOS attacks, as its simple to trick users into allowing the browser to access the BLE hardware

RE: Simple direct advertising

clementfumey — Wed, 09 Nov 2016 15:46:58 GMT

As far as I understood, direct advertisement should be ignored by a central scanner which address doesn't match the peer_address. So for a not too curious central the advertisement is "hidden". In my application the main goal is to know if a node is advertising or not. For this purpose, I want to "hide" my advertisements from others central than mine to avoid someone replicate my advertisement and make my central believe a beacon is alive.I know this is a very basic security scheme, but this is only a first step!

RE: Simple direct advertising

Roger Clark — Wed, 09 Nov 2016 09:45:32 GMT

I would be interested to know how you can hide a advertisement and yet for it still to be useful.

Something must be capable of receiving your advertisement otherwise the system would be useless.

If you just want to send some sort of non-standard advertising data, I think you're going to need to build the advertising packet yourself and call the lower level functions in the API and not call functions like ble_advdata_set()