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141 lines
7.2 KiB
Markdown
141 lines
7.2 KiB
Markdown
# Simple Sniffer Example
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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## Overview
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This example demonstrates basic usage of WiFi sniffer mode by saving packets into SD card with pcap format. We can send pcap file to host via JTAG interface as well.
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For more information about pcap, please go to [wikipedia](https://en.wikipedia.org/wiki/Pcap).
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This example is based on console component. For more information about console, please refer to [console guide](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/console.html).
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## How to use example
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### Hardware Required
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To run this example, you should have one ESP32 dev board integrated with a SD card slot (e.g [ESP-WROVER-KIT](https://docs.espressif.com/projects/esp-idf/en/latest/hw-reference/modules-and-boards.html#esp-wrover-kit-v4-1)) or just connect [ESP32-DevKitC](https://docs.espressif.com/projects/esp-idf/en/latest/hw-reference/modules-and-boards.html#esp32-devkitc-v4) to a SD card breakout board.
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If you want to send packets to host, make sure to connect ESP32 to some kind of [JTAG adapter](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/jtag-debugging/index.html#jtag-debugging-selecting-jtag-adapter).
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### Configure the project
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Open the project configuration menu (`idf.py menuconfig`). Then go into `Example Configuration` menu.
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- Check `Store command history in flash` if you want to save command history into flash (recommend).
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- Select where to save the pcap file in `Select destination to store pcap file` menu item.
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- `SD Card` means saving packets (pcap format) into the SD card you plug in.
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- `JTAG (App Trace)` means sending packets (pcap format) to host via JTAG interface. This feature depends on [app trace component](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/app_trace.html).
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- Set the mount point in your filesystem in `SD card mount point in the filesystem` menu item. This configuration only takes effect when you choose to save packets into SD card.
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- Set max name length of pcap file in `Max name length of pcap file` menu item.
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- Set the length of sniffer work queue in `Length of sniffer work queue` menu item.
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- Set the stack size of the sniffer task in `Stack size of sniffer task` menu item.
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- Set the priority of the sniffer task `Length of sniffer work queue` menu item.
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### Build and Flash
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```
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idf.py -p PORT flash monitor
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```
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(Replace PORT with name of the serial port.)
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the [Getting Started Guide](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) for full steps to configure and use ESP-IDF to build projects.
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## Example Output
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### `sniffer` Command Usage
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> sniffer [-f <file>][-i ] [-F <mgmt|data|ctrl|misc|mpdu|ampdu>]... [-c <channel>][--stop]
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> Capture specific packet and store in pcap format
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> -f, --file=<file> name of the file storing the packets in pcap format
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> -i, --interface=<wlan> which interface to capture packet
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> -F, --filter=<mgmt|data|ctrl|misc|mpdu|ampdu> filter parameters
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> -c, --channel=<channel> communication channel to use
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> --stop stop running sniffer
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The `sniffer` command support some important options as follow:
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* `-f`: Specify the name of file who will store the packets, default value is `sniffer`, and the resulting file name will be like “snifferX.pcap”, here ‘X’ shows the file’s order.
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* `-i`: Specify the interface to sniffer packets, currently only support `wlan`
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* `-c` :Specify the channel to sniffer packet
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* `-F`: Specify the filter condition, currently only support following filter conditions, you can select any number of them
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* mgmt: Management packets
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* data: Data packets
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* ctrl: Control packets
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* misc: Other packets
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* mpdu: MPDU packets
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* ampdu: AMPDU packets
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* `--stop`: Stop sniffer job
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### Mount SD Card
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```bash
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=======================================================
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| Steps to sniffer WiFi packets |
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| 1. Enter 'help' to check all commands' usage |
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| 2. Enter 'mount <device>' to mount filesystem |
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| 3. Enter 'sniffer' to start capture packets |
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| 4. Enter 'unmount <device>' to unmount filesystem |
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=======================================================
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esp32> mount sd
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I (158912) example: Initializing SD card
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I (158912) example: Using SDMMC peripheral
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I (158912) gpio: GPIO[13]| InputEn: 0| OutputEn: 1| OpenDrain: 0| Pullup: 0| Pulldown: 0| Intr:0
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Name: SA16G
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Type: SDHC/SDXC
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Speed: 20 MHz
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Size: 14832MB
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```
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### Start Sniffer
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```bash
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esp32> sniffer -f sniffer-example -i wlan -c 2
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I (8946) cmd_sniffer: open file successfully
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W (8966) phy_init: failed to load RF calibration data (0x1102), falling back to full calibration
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I (9176) phy: phy_version: 4100, 6fa5e27, Jan 25 2019, 17:02:06, 0, 2
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I (9186) wifi: ic_enable_sniffer
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I (9196) cmd_sniffer: start WiFi promiscuous ok
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esp32> sniffer --stop
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I (31456) wifi: ic_disable_sniffer
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I (31456) wifi: flush txq
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I (31456) wifi: stop sw txq
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I (31456) wifi: lmac stop hw txq
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I (31456) cmd_sniffer: stop WiFi promiscuous ok
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```
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### Unmount SD Card
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```bash
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esp32> unmount sd
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I (248800) example: Card unmounted
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```
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### Steps for sending packets to host via JTAG interface
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1. Select `JTAG (App Trace)` as the destination of pcap files.
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2. Build & Flash with `idf.py -p PORT flash`
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3. Connect JTAG, run OpenOCD (for more information about how-to please refer to [JTAG Debugging](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/jtag-debugging/index.html)).
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4. Telnet to localhost with 4444 port: `telnet localhost 4444`.
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5. In the telnet session, run command like `esp32 apptrace start file://sniffer-esp32.pcap 1 -1 20` (more information about this command, please refer to [apptrace command](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/app_trace.html#openocd-application-level-tracing-commands)).
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6. Run the example, start sniffer with command `sniffer` (you don't need to specify the filename, because it has been set in step5).
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7. Stop sniffer by entering command `sniffer --stop` in the example console.
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8. Stop tracing by entering command `esp32 apptrace stop` in the telnet session.
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### Open PCap File in Wireshark
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## Troubleshooting
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- Make sure you have pluged in your SD card and mount it into filesystem before doing sniffer work or you will get error message like “Create file /sdcard/sniffer0.pcap failed”.
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- To protect the SD card, we recommand you to execute command `unmount sd` before you plug out your SD card.
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- Make sure to run `esp32 apptrace` command before or immediately after a new sniffer task started when you try this example with JTAG. Otherwise the console will issue warning message `waiting for apptrace established` every 1 second. If the apptrace communication doesn't be established within 10 seconds (can be altered by macro `SNIFFER_APPTRACE_RETRY`), this sniffer command will failed with an error message `waiting for apptrace established timeout`.
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(For any technical queries, please open an [issue](https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you as soon as possible.)
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