Capturing network traffic and saving it as a PCAP file is a common practice for log analysis, debugging, and security auditing. Below is a comprehensive guide for both rooted and non-rooted Android devices, including the use of Termux and VPN-based solutions.
For Rooted Devices
Rooted devices provide more flexibility as you can directly access low-level network interfaces. The following methods are recommended:
Method 1: Using tcpdump
2. Install tcpdump:
- Download the tcpdump binary:
wget https://www.tcpdump.org/release/tcpdump-4.99.4.tar.gz
- Extract and install:
tar -xvf tcpdump-4.99.4.tar.gz cd tcpdump-4.99.4 ./configure make make install
- Alternatively, you can copy a precompiled
tcpdump
binary to your phone using ADB:adb push tcpdump /data/local/tmp/ adb shell chmod +x /data/local/tmp/tcpdump
2. Run tcpdump:
- Open a terminal app (like Termux or a terminal emulator).
- Run tcpdump to capture packets:
/data/local/tmp/tcpdump -i any -w /sdcard/capture.pcap
- Stop the capture with
Ctrl+C
.
3. Transfer the PCAP File:
- Use ADB or file transfer to copy the file to your computer for analysis:
adb pull /sdcard/capture.pcap
Method 2: Using Shark for Root
Shark for Root is a graphical frontend for tcpdump
.
Steps:
- Install Shark for Root from a trusted APK source.
- Open the app and start capturing packets.
- Save the capture when done.
- Transfer the PCAP file to your computer for analysis.
For Non-Rooted Devices
Non-rooted devices can still capture traffic using apps that leverage a local VPN interface. However, these methods may have limitations (e.g., inability to capture traffic outside the app scope).
Method 1: Using Packet Capture
Packet Capture is an Android app available on the Play Store.
Steps:
- Install Packet Capture from the Play Store.
- Launch the app and start capturing traffic.
- If capturing HTTPS traffic, follow the instructions to install the app’s SSL certificate.
- Stop the capture and save the file as a PCAP.
- Transfer the PCAP file to your computer for further analysis.
Method 2: Using tPacketCapture
tPacketCapture is another non-root option available on the Play Store.
Steps:
- Install tPacketCapture.
- Launch the app and start capturing.
- Save the log in PCAP format.
- Transfer the file for analysis.
Using Termux for PCAP Capture
Termux allows for terminal-based operations on non-rooted or rooted devices.
For Rooted Devices in Termux
-
Install tcpdump in Termux:
pkg install tcpdump
-
Run tcpdump:
tcpdump -i any -w /sdcard/capture.pcap
- Replace
/sdcard/capture.pcap
with your desired file path.
- Replace
-
Stop the Capture:
- Use
Ctrl+C
to end the process.
- Use
-
Transfer the File:
adb pull /sdcard/capture.pcap
For Non-Rooted Devices in Termux
Non-rooted Termux users can use VPN-based apps to capture traffic while managing the PCAP files in Termux.
Analyzing HTTPS Traffic
Decrypt HTTPS Traffic
- Install the capturing app’s SSL certificate.
- Configure your network or browser to trust the certificate.
- Use tools like Wireshark to decode HTTPS streams.
Transfer and Analysis
Transfer PCAP File:
- Use ADB:
adb pull /sdcard/capture.pcap
- Or upload to cloud storage (Google Drive, Dropbox).
Analyze with Wireshark:
- Open Wireshark on your computer.
- Load the PCAP file:
File -> Open -> Select capture.pcap
- Analyze the captured traffic using filters and protocols.
This guide provides detailed instructions for both rooted and non-rooted devices, covering a range of tools and methods.