What is Bluetooth HCI Snoop Log? (Host Controller Interface)
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If you are an Android owner, you might not realize it but your phone is full of hidden settings and commands. A lot of these settings were put in place to help debug and develop new apps but within this long list of settings and commands, you’ll find something particularly useful—Bluetooth HCI Snoop Log.
The Bluetooth HCI Snoop Log gives developers and security analysts access to Bluetooth host controller interface packets. When enabled, the Bluetooth HCI Snoop Log captures and stores these packets in an accessible file in your device’s storage log. It can later be retrieved and analyzed with specific software.
Let’s take a deeper look at what the Bluetooth HCI Snoop Log does and how you can access it on your Android device. If you’re ready to get into the inner workings of your phone, let’s get started.
What do Bluetooth HCI Snoop Logs Do?
A Bluetooth HCI snoop log is a type of log file that stores all of the transmissions sent through Bluetooth on your Android device. If you can access a Bluetooth HCI snoop log, it means you’ve downloaded an app that logs data on your phone through Bluetooth communication and transmission. This data is automatically logged and backed up into the snoop log.
If this sounds like a possible invasion of privacy, don’t worry. Bluetooth HCI snoop logs do not export your data. All of the logs are simply stored on your phone and be accessed and analyzed at a later date. You just have to know how to access the logs.
Most Android devices are developed with existing HCI logging software but if you’re currently using a device that predates Android 4.4+, you may need to download a third-party app to log and access your Bluetooth HCI snoop logs.
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What are HCI Logs?
A host controller interface (HCI) log is a record of all HCI processes performed on your device. The host controller interface acts as an intermediary between the controller and host elements of your device’s Bluetooth protocol stack. It’s implemented in a host_test project through specific protocols, including UART and SPI.
Newer Android devices are developed using modern Bluetooth Low Energy (BLE) protocol stacks, which speed up hops at wider frequencies. This helps limit the amount of external interference and allows your device to quickly identify nearby Bluetooth frequencies while simultaneously filtering out non-necessary signals.
This helps increase device security, preventing data from being lost in the Bluetooth transmission process. The HCI log keeps a record of this data transfer so you can later examine it for potential security risks and performance problems.
How to Create and Access a Bluetooth HCI Snoop Log
Before you can export and access a Bluetooth HCI snoop log, you must first enable your device’s developer settings. These settings are usually hidden out of sight to keep unwittingly phone owners from irreversibly tampering with their phone’s inner workings. However, you can gain access to the developer settings by tapping the builder number seven times in your Android settings.
- After accessing your device’s developer settings,
- go into the main menu and
- locate the “Enable Bluetooth HCI Snoop Log” checkbox.
- Click the checkbox to start the log, then stop it again before exporting the final file.
- The final log will be stored as a btsnoop_hci.log file in your device’s USD root or SD storage.
To access the file, you will need specific network protocol analysis software such as Wireshark.
Before opening the files, rename them to *.cap and then process them through the software. You’ll be able to view the host controller interface protocols and analyze them for corruption or security breaches.
You have two options for retrieving and viewing HCI logs:
1. You can export and view Bluetooth HCI snoop logs by connecting your android device to a desktop computer and locating the files stored in your mountable drives. Locate the file at C:/Users/Public/Public Documents/Frontline Test Equipment/My Capture File/ then export it into your third-party protocol analysis software.
2. You can export and view Bluetooth HCI snoop logs by using the Android debugging bridge that comes preloaded on your device. It should be listed under the same developer settings discussed up above. Follow these steps if you want to use this option:
- Tap the builder number in your settings seven times to access the settings and find the debugging bridge in the main menu.
- Connect your device to a desktop computer
- Open a commands terminal and run ‘adb devices’. Your Android device should appear in the list.
- Copy and paste this command into the terminal – ‘adb pull /sdcard/btsnoop_hci.log’
This command should pull up your device’s Bluetooth HCI snoop log.
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What is Wireshark Software?
Wireshark is a downloadable software used to analyze, or “sniff”, network protocols. It captures data packets, such as Bluetooth HCI snoop logs, and stores them in discrete data files that can later be accessed and analyzed.
Wireshark is the most commonly used software for sniffing data packets and, like any protocol analyzer, it:
- Captures data packets – Wireshark analyzes and collects information from your network connection in real-time, creating a screenshot of your data traffic made up of thousands of packets at once.
- Filters data – While it collects a stream of data, Wireshark is able to process the information using specific filters. By using these filters, you can single out individual bits of information to narrow down your analysis.
- Visualizes information – Wireshark simplifies complex streams of information into easily understandable visuals. You can quickly process entire conversations into clean and useable bits of information.
Think of this process as digital spelunking. Wireshark acts as the flashlight, allowing you to dive into your Android’s inner world and pull out hidden gems of data. It is safe and commonly used by university systems, corporations, and several government agencies around the world
Bluetooth HCI snoop logs are a backed-up record of transmissions sent through your Bluetooth host controller interface. The logs are stored in your device but can be exported and viewed using data analysis software such as Wireshark.
Check this article about 10 Smart Bluetooth Devices to Take Your Home To The Next Level.
Espen is the Director of ProPairing and has written extensively about Bluetooth devices for years. He is a consumer product expert and has personally tested Bluetooth devices for the last decade.