Extension Overview

Extend InterceptSuite functionality with custom Python 3 extensions.

Overview

InterceptSuite allows you to write custom extensions in Python 3 that integrate directly with the proxy engine. Extensions can read, process, transform, and display packet data in ways the built-in viewer doesn't support.

Use cases include:

Decoding custom or proprietary binary protocols
Parsing application-layer data (JSON, XML, Base64, protobuf, etc.)
Adding custom data viewer tabs for specific packet types
Automating packet analysis and logging
Building custom alerting on specific packet patterns

Python Requirements

Supported Versions

Requirement	Details
Python Version	3.8 to 3.12
Implementation	CPython only
Package Support	Any pip-installable package
System Install	Python must be installed on the host system

Extensions will not load if Python is not installed or not configured in InterceptSuite settings.

Locating Your Python Installation

Platform	Common Path
Windows	`C:\Python312\` or `C:\Users\<name>\AppData\Local\Programs\Python\Python312\`
macOS	`/Library/Frameworks/Python.framework/Versions/3.12/bin`
Linux	`/usr/bin` or `/usr/local/bin`

Python Configuration

Before adding extensions, you must tell InterceptSuite where Python is installed:

Go to Extension tab → Settings tab
Click Browse and select your Python installation directory
After selecting, you should see a green dot with "Python configuration found"

This is a one-time setting -InterceptSuite saves the path and uses it for all future sessions.

Extension Management

Adding an Extension

Go to Extension tab → Extensions tab
Click Add
Browse to and select your Python extension .py file
The extension path is saved and the extension is automatically loaded on future app launches

Removing an Extension

Select the extension in the table
Click Remove
The extension is permanently removed from configuration and will not load on the next launch

Enabling and Disabling Extensions

Use the checkbox next to each extension to temporarily unload it without removing it:

Checked -Extension is loaded and active
Unchecked -Extension is unloaded but remains in configuration
On the next app launch, InterceptSuite respects the last enabled/disabled state

Benefits of temporarily unloading:

Isolate issues by disabling extensions one at a time
Improve performance by unloading unused extensions
Test extension interactions selectively

Extension Purposes

Packet Data Processing

Extensions can hook into the packet data pipeline to:

Read and analyze packet payloads in real-time
Apply custom transformations to data
Log, filter, or annotate packet content

Protocol Dissection

Add support for application-layer protocols that InterceptSuite doesn't natively understand:

Parse binary protocol formats
Decode proprietary wire formats
Extract fields from structured data

Custom Data Viewer Tabs

Extensions can add custom tabs to the packet viewer alongside the built-in Raw and Hex tabs. For example, you could add a Base64, JSON, Protobuf, or Custom Protocol tab that automatically decodes packet data for easy reading.

See the Extension API Reference for full implementation details.

Development Resources

Extension API Reference -Full API documentation: Extension API
Example Extensions -Working sample extensions: github.com/InterceptSuite/Extension

Best Practices

Development

Implement robust exception handling -unhandled exceptions in extensions can affect proxy stability
Optimize extension performance to avoid adding latency to the proxy pipeline
Test extensions against known-good traffic before using in real analysis sessions

Management

Keep extension .py files in a dedicated, version-controlled directory
Document what each extension does and its dependencies
Use virtual environments to manage extension package dependencies

Security

Review all third-party code before using it as an extension
Be cautious with extensions that make outbound network requests
Consider what file system access your extensions require