Summary
Bluetooth is a short-range wireless technology that allows broadcasting the data over specific Bluetooth channels.
There are 40 unique bands (channels) and each band has a 2 MHz separation. 37, 38, and 39 channels are used for advertising, and 0-36 are used for data transmission.
During the advertising process, the BLE advertising packet is broadcasted. This packet contains the Preamble, Access Address, PDU and CRS fields.
The Preamble and Access Address fields help the receiver detect frames. CRS field is used to check errors. PDU consists of PDU Header and PDU Payload. PDU defines the packet itself.
PDU Header contains information about the PDU type. Based on the type, the payload fields may differ.
For example, when PDU type is ADV_NONCONN_IND → PDU Payload consists of "AdvA" (a field that contains information about the advertiser's address) and "AdvData" (a field that contains data information) fields:
1 octet = 1 byte = 8 bits
| Preamble | 1 octet |
| Access-Address | 4 octets |
| PDU |
|
| CRS | 3 octets |
There are different PDU types, like:
- ADV_IND (where payload consists of AdvA [6octets] + AdvData [0-31 octets] and which is used for connectable, scannable undirected advertising);
- ADV_NOCONN_IND (where payload consists of AdvA [6octets] + AdvData [0-31 octets] and which is used for non-connectable, non-scannable undirected advertising);
- ADV_SCAN_IND (where payload consists of AdvA [6octets] + AdvData [0-31 octets] and which is used for scannable, undirected advertising);
- SCAN_REQ (where payload consists of ScanA [6octets] + AdvA [6octets], where ScanA field contains scanner's address and AdvA contains advertiser's address, and which is used for requesting SCAN_RSP response);
- SCAN_RSP (where payload consists of AdvA [6octets] + ScanRspData [0-31 octets], where ScanRspData can contain any data from the advertiser's host and which is used to reply/respond to a scannable advertisement);
- ADV_DIRECT_IND (where payload consists of AdvA [6octets] + TargetA [6octets], where TargetA is the device address field to which the PDU is addressed, and which is used for connectable, directed advertising);
- etc
You can find more information about the packet structure over here (Bluetooth specifications).
The main application for the Bluetooth interface in RouterOS is to monitor Bluetooth advertising packets (scanner feature) that are broadcasted by other devices (like for example, Bluetooth tags) or broadcast advertising packets (advertiser feature).
Configuration
Sub-menu: /iot bluetooth
note: iot package is required.
note: Check your device's specifications page to make sure that the Bluetooth is supported by the unit.
IoT package is available with RouterOS version 6.48.3. You can get it from our download page - under "Extra packages".
Devices
In this menu you can check and set general Bluetooth chip parameters:
[admin@device] > iot bluetooth print Columns: NAME, PUBLIC-ADDRESS, RANDOM-STATIC-ADDRESS, ANTENNA # NAM PUBLIC-ADDRESS RANDOM-STATIC-ADD ANTENNA 0 bt1 00:00:00:00:00:00 F4:4E:E8:04:77:3A internal [admin@device] /iot bluetooth set
note: Public address is the IEEE registered, permanent address. This address can not be changed.
Configurable settings are shown below:
| Property | Description |
|---|---|
| antenna (string; Default: internal) | Choose whether to use an internal or an external Bluetooth antenna |
| name (string; Default: ) | Descriptive name of Bluetooth chip/interface |
random-static-address (MAC address; Default: ) | A unique static user-configurable address for the Bluetooth chip |
You can monitor chip stats with the command:
[admin@device] /iot bluetooth print stats Columns: NAME, RX-BYTES, TX-BYTES, RX-ERRORS, TX-ERRORS, RX-EVT, TX-CMD, RX-ACL, TX-ACL # NAM RX-BYTE TX- R T RX-EV TX R T 0 bt1 1857835 235 0 0 46677 45 0 0
Advertisers
In this menu, it is possible to set up the Bluetooth chip to broadcast advertising packets. You can check and set advertiser settings with the commands:
[admin@device] > iot bluetooth advertisers print
Flags: X - DISABLED
Columns: DEVICE, MIN-INTERVAL, MAX-INTERVAL, OWN-ADDRESS-TYPE, CHANNEL-MAP, AD-SIZE
# DEVICE MIN-INTERVAL MAX-INTERVAL OWN-ADDRESS-TYPE CHANNEL-MAP AD-SIZE
0 X bt1 1280ms 2560ms random-static 37 0
38
39
[admin@device] /iot bluetooth advertisers set
Configurable settings are shown below:
| Property | Description |
|---|---|
| ad-structures (string; Default: ) | Choose a pre-configured structure for the advertisement packets. For more information see the "AD structures" section. |
| channel-map (37 | 38 | 39; Default: 37, 38, 39) | Channels used for advertising. |
disabled (yes | no; Default: yes) | An option to disable or enable the Bluetooth chip to broadcast advertising packets. |
max-interval (integer:20..10240; Default: 1280 ms) | The maximal interval for broadcasting advertising packets. |
min-interval (integer:20..10240; Default: 2560 ms) | The minimal interval for broadcasting advertising packets. |
own-address-type (public | random-static | rpa-fallback-to-public | rpa-fallback-to-random; Default: random-static) | The MAC address that is going to be used in the advertising packet's payload:
|
note: Advertising packets will be broadcasted each min-interval > X < max interval milliseconds.
AD structures
This section allows you to define the payload for the advertising packets that are going to be broadcasted by the Bluetooth chip.
Currently, only 3 types are supported: 0x08 "Shortened Local Name"; 0x09 "Complete Local Name"; 0xFF "Manufacturer Specific Data".
You can check and set "AD structures" settings with the commands:
[admin@device] > iot bluetooth advertisers ad-structures print Columns: NAME, TYPE, DATA # NAME TYPE DATA 0 test short-local-name test [admin@device] > iot bluetooth advertisers ad-structures set
Configurable properties are shown below:
| Property | Description |
|---|---|
| data (string; Default: ) | Define advertising packet's AdvData part of the payload |
| name (string; Default: ) | Descriptive name of AD structure |
type (complete-local-name | manufacturer-data | short-local-name; Default: ) | An option to set AD structure's type:
|
If, for example, the "Shortened Local Name" type is chosen and the "data" field is configured with "test" → AdvData part of the payload is going to look like this:
05 08 54 45 53 54 (hexadecimal format)
, where the first octet (05) shows the length (5 bits) and the second octet (08) shows the type (Shortened Local Name). 3d, 4th, 5th and 6th (and etc) octets are the "data" [54 (hex)=T (ASCII), 45 (hex)=E (ASCII), 53 (hex)=S (ASCII), 54 (hex)=T (ASCII)].
The same applies to the "Complete Local Name" type. Only the second octet in the AdvData payload is going to differ and will be set to 09.
For the "Manufacturer Specific Data" type, you will need to configure the "data" field in the hexadecimal format. The second octet for this type is going to be set to FF.
Scanners
In this menu, you can set up the scanner settings for the Bluetooth chip. When disabled, the device is no longer able to receive advertising reports. When enabled, you can monitor advertising reports in the "Advertising reports" tab (which will be explained later in the guide). You can check and set scanner settings with the commands:
[admin@device] > iot bluetooth scanners print Flags: X - DISABLED Columns: DEVICE, TYPE, INTERVAL, WINDOW, OWN-ADDRESS-TYPE, FILTER-POLICY, FILTER-DUPL ICATES # DEVICE TYPE INTERVAL WINDOW OWN-ADDRESS-TYPE FILTER-POLICY FIL 0 X bt1 passive 10ms 10ms random-static default off [admin@device] /iot bluetooth scanners set
Configurable properties are shown below:
| Property | Description |
|---|---|
| disabled (yes | no; Default: no) | An option to disable or enable the Bluetooth chip to receive advertising reports. |
| filter-duplicates (keep-newest | keep-oldest | off; Default: off) | An option to discard duplicate advertisements from the same advertiser:
|
filter-policy (default | whitelist | no; Default: default) | An option to set up a filtering policy (controller-level advertisement filtering):
|
interval (integer:3..10240; Default: 10 ms) | Time after which scanner will start scanning the next advertisement channel. |
own-address-type (public | random-static | rpa-fallback-to-public | rpa-fallback-to-random; Default: random-static) | Address type used in scan requests (if active scanning type is used):
|
type (active | passive; Default: passive) | Defines the scanner's type:
|
| window (integer:3..10240; Default: 10 ms) | Time scanner will spend scanning a single advertisement channel. |
For example, if the scanner interval is set to 20ms, it means that only after 20ms, the device will begin scanning the next channel in line. If the scanner window is set to 10ms, it means that the device will scan each channel only during that 10ms window. Meaning, it will scan channel 37 for 10ms (window time) and begin scanning the next channel after 10 more ms (20ms[interval]-10ms[window]). It will take 10ms to scan channel 38, and after 10 more ms, the device will begin scanning channel 39.
Advertising reports
In this section, it is possible to monitor Bluetooth advertising reports (from the nearby broadcasters). You can monitor advertising reports with the command:
[admin@device] > iot bluetooth scanners advertisements print Columns: DEVICE, PDU-TYPE, TIME, ADDRESS-TYPE, ADDRESS, RSSI # DEV PDU-TYPE TIME ADDRES ADDRESS RSSI 0 bt1 adv-noconn-ind jul/28/2021 09:30:56 public 2C:C8:1B:93:16:49 -24dBm 1 bt1 adv-noconn-ind jul/28/2021 09:30:56 random 0B:16:17:9E:7B:EF -60dBm
It is possible to set up a filter for the reports with the command:
[admin@device] > iot bluetooth scanners advertisements print where
For example, to print only reports that are broadcasted only by a specific MAC address, use the command:
[admin@device] > iot bluetooth scanners advertisements print where address=XX:XX:XX:XX:XX:XX # DEVICE PDU-TYPE TIME ADD... ADDRESS RSSI LENGTH DATA 79 bt1 adv-noconn-ind jul/28/2021 09:46:38 public XX:XX:XX:XX:XX:XX -70dBm 30 02010... 80 bt1 adv-noconn-ind jul/28/2021 09:46:43 public XX:XX:XX:XX:XX:XX -67dBm 30 02010... 81 bt1 adv-noconn-ind jul/28/2021 09:46:44 public XX:XX:XX:XX:XX:XX -70dBm 28 1bff0... 82 bt1 adv-noconn-ind jul/28/2021 09:46:48 public XX:XX:XX:XX:XX:XX -75dBm 30 02010...
Possible filters are shown below:
| Filter | Description |
|---|---|
| id | Item number |
| address | Advertiser Bluetooth address |
data | Advertisement data in hex format |
| epoch | Milliseconds since Unix Epoch |
| filter-comment | Comment of the matching whitelist filter |
| length | Advertisement data length |
| rssi | Signal strength |