A high-performance, cross-platform network monitoring tool built with Rust. RustNet provides real-time visibility into network connections with enhanced state display, intelligent connection lifecycle management, deep packet inspection capabilities, and a responsive terminal user interface.

Features

Real-time Network Monitoring: Monitor active TCP, UDP, ICMP, and ARP connections with enhanced state visibility
Intelligent Connection States: Rich state display showing exactly what each connection is doing:
- TCP States: ESTABLISHED, SYN_SENT, TIME_WAIT, CLOSED, etc.
- QUIC States: QUIC_INITIAL, QUIC_HANDSHAKE, QUIC_CONNECTED, QUIC_DRAINING
- DNS States: DNS_QUERY, DNS_RESPONSE
- Activity States: UDP_ACTIVE, UDP_IDLE, UDP_STALE based on connection activity
Deep Packet Inspection (DPI): Automatically detect application protocols:
- HTTP with host information
- HTTPS/TLS with SNI (Server Name Indication)
- DNS queries and responses
- TODO: SSH connections
- QUIC protocol with CONNECTION_CLOSE frame detection and proper RFC 9000 compliance
Smart Connection Lifecycle Management:
- Dynamic timeouts based on protocol, state, and activity (TCP closed: 5s, QUIC draining: 10s, SSH: 30min)
- Protocol-aware cleanup (DNS: 30s, established TCP: 5min, QUIC with close frames: 1-10s)
- Activity-based timeout scaling for long-lived vs idle connections
Process Identification: Associate network connections with running processes
Service Name Resolution: Identify well-known services using port numbers
Cross-platform Support: Works on Linux, macOS and potentially on Windows and BSD systems
Terminal User Interface: Clean, responsive TUI built with ratatui with optimized column widths for state visibility
Performance Optimized: Multi-threaded packet processing with minimal overhead
Optional Logging: Detailed logging with configurable log levels (disabled by default)

Installation

Prerequisites

Rust 2024 edition or later (install from rustup.rs)
libpcap or similar packet capture library:
- Linux: sudo apt-get install libpcap-dev (Debian/Ubuntu) or sudo yum install libpcap-devel (RedHat/CentOS)
- macOS: Included by default
- Windows: Install WinPcap or Npcap

Building from source

# Clone the repository
git clone https://github.com/domcyrus/rustnet.git
cd rustnet

# Build in release mode
cargo build --release

# The executable will be in target/release/rustnet

Running RustNet

On Unix-like systems (Linux/macOS), packet capture typically requires elevated privileges:

# Run with sudo
sudo ./target/release/rustnet

# Or set capabilities on Linux (to avoid needing sudo)
sudo setcap cap_net_raw,cap_net_admin=eip ./target/release/rustnet
./target/release/rustnet

Usage

# Run with default settings (monitors default interface)
rustnet

# Specify network interface
rustnet -i eth0
rustnet --interface wlan0

# Filter out localhost connections
rustnet --no-localhost

# Set UI refresh interval (in milliseconds)
rustnet -r 500
rustnet --refresh-interval 2000

# Disable deep packet inspection
rustnet --no-dpi

# Enable logging with specific level (options: error, warn, info, debug, trace)
rustnet -l debug
rustnet --log-level info

# View help and all options
rustnet --help

Command-line Options

Usage: rustnet [OPTIONS]

Options: -i, --interface Network interface to monitor --no-localhost Filter out localhost connections -r, --refresh-interval UI refresh interval in milliseconds [default: 1000] --no-dpi Disable deep packet inspection -l, --log-level Set the log level (if not provided, no logging will be enabled) -h, --help Print help -V, --version Print version

Keyboard Controls

q: Quit the application (press twice to confirm)
Ctrl+C: Quit immediately
Tab: Switch between tabs (Overview, Details, Help)
↑/k: Navigate up in connection list
↓/j: Navigate down in connection list
PageUp: Move up by 10 items
PageDown: Move down by 10 items
Enter: View detailed information about selected connection
Esc: Go back to previous view
c: Copy remote address to clipboard
h: Toggle help screen

Logging

Logging is disabled by default for better performance. When enabled with the --log-level option, RustNet creates timestamped log files in the logs/ directory. Each session generates a new log file with the format rustnet_YYYY-MM-DD_HH-MM-SS.log.

Log files contain:

Application startup and shutdown events
Network interface information
Packet capture statistics
Connection state changes
Error diagnostics

To enable logging, use the --log-level option:

# Enable info-level logging
sudo rustnet --log-level info

# Enable debug-level logging for troubleshooting
sudo rustnet --log-level debug

The scripts/clear_old_logs.sh script is provided for log cleanup.

Architecture

RustNet employs a multi-threaded architecture for high-performance packet processing:

┌─────────────────┐
│ Packet Capture  │ ──packets──> Crossbeam Channel
│   (libpcap)     │                      │
└─────────────────┘                      │
                                         ├──> ┌──────────────────┐
                                         ├──> │ Packet Processor │ ──> DashMap
                                         ├──> │    (Thread 0)    │      │
                                         └──> │    (Thread N)    │      │
                                              └──────────────────┘      │
                                                                        │
┌─────────────────┐                                                     │
│Process Enrichment│ ────────────────────────────────────────────> DashMap
│  (Platform API) │                                                     │
└─────────────────┘                                                     │
                                                                        │
┌─────────────────┐                                                     │
│Snapshot Provider│ <─────────────────────────────────────────── DashMap
└─────────────────┘                                                     │
         │                                                              │
         └──> RwLock<Vec<Connection>> (for UI)                          │
                                                                        │
┌─────────────────┐                                                     │
│ Cleanup Thread  │ <─────────────────────────────────────────── DashMap
└─────────────────┘

Key Components

Packet Capture Thread: Uses libpcap to capture raw packets from the network interface
Packet Processors: Multiple worker threads parse packets and perform DPI analysis
Process Enrichment: Platform-specific APIs to associate connections with processes
Snapshot Provider: Creates consistent snapshots for the UI at regular intervals
Smart Cleanup Thread: Removes connections using dynamic timeouts based on protocol, state, and activity
DashMap: Lock-free concurrent hashmap for storing connection state

Dependencies

RustNet is built with the following key dependencies:

ratatui: Terminal user interface framework with full widget support
crossterm: Cross-platform terminal manipulation
pcap: Packet capture library bindings
pnet_datalink: Network interface enumeration
dashmap: High-performance concurrent hashmap
crossbeam: Multi-threading utilities and channels
dns-lookup: DNS resolution capabilities
clap: Command-line argument parsing with derive features
simplelog: Flexible logging framework
anyhow: Error handling and context
arboard: Clipboard access for copying addresses
log: Logging facade
num_cpus: CPU core detection for threading
simple-logging: Additional logging utilities
chrono: Date and time handling
ring: Cryptographic operations
aes: AES encryption support
procfs (Linux): Process information from /proc filesystem

Platform-Specific Implementation

Process Lookup

RustNet uses platform-specific APIs to associate network connections with processes:

Linux: Parses /proc/net/tcp, /proc/net/udp, and /proc/<pid>/fd/ to find socket inodes
macOS: Uses PKTAP (Packet Tap) headers when available for direct process identification from packet metadata, with fallback to lsof system commands for process-socket associations. PKTAP provides more accurate and efficient process identification by extracting process information directly from the kernel packet headers.
Windows: Uses nothing so far :)

Network Interfaces

The tool automatically detects and lists available network interfaces using platform-specific methods, falling back to pcap's device enumeration when native methods are unavailable.

Performance Considerations

Multi-threaded Processing: Packet processing is distributed across multiple threads (up to 4 by default)
Lock-free Data Structures: Uses DashMap for concurrent access without traditional locking
Batch Processing: Packets are processed in batches to improve cache efficiency
Selective DPI: Deep packet inspection can be disabled with --no-dpi for lower overhead
Configurable Intervals: Adjust refresh rates based on your needs

Troubleshooting

Common Issues

Permission Denied: Packet capture requires elevated privileges. Run with sudo or set capabilities.
No Connections Shown:
- Check if the correct network interface is selected
- Verify packet capture permissions
- Try disabling localhost filtering with --no-localhost
High CPU Usage:
- Increase the refresh interval: --refresh-interval 2000
- Disable DPI if not needed: --no-dpi
- Check log files for excessive packet rates
Process Names Not Showing:
- On Linux, ensure /proc is accessible
- Some processes may require root privileges to identify

Debug Mode

Enable debug logging to troubleshoot issues:

sudo rustnet --log-level debug

Check the generated log file in the logs/ directory for detailed diagnostics. Note that logging is disabled by default, so you must explicitly enable it with the --log-level option.

Security Considerations

RustNet requires privileged access for packet capture
The tool only monitors traffic; it does not modify or block connections
Log files may contain sensitive connection information
No data is transmitted outside your system

Permissions

RustNet requires elevated privileges to capture network packets because accessing network interfaces for packet capture is a privileged operation on all modern operating systems. This section explains how to properly grant these permissions on different platforms.

Why Permissions Are Required

Network packet capture requires access to:

Raw sockets for low-level network access
Network interfaces in promiscuous mode
BPF (Berkeley Packet Filter) devices on macOS/BSD systems
Network namespaces on some Linux configurations

These capabilities are restricted to prevent malicious software from intercepting network traffic.

macOS Permission Setup

On macOS, packet capture requires access to BPF (Berkeley Packet Filter) devices located at /dev/bpf*.

Option 1: Run with sudo (Simplest)

# Build and run with sudo
cargo build --release
sudo ./target/release/rustnet

Option 2: BPF Group Access (Recommended)

Add your user to the access_bpf group for passwordless packet capture:

Using Wireshark's ChmodBPF (Easiest):

# Install Wireshark's BPF permission helper
brew install --cask wireshark-chmodbpf

# Log out and back in for group changes to take effect
# Then run rustnet without sudo:
rustnet

Manual BPF Group Setup:

# Create the access_bpf group (if it doesn't exist)
sudo dseditgroup -o create access_bpf

# Add your user to the group
sudo dseditgroup -o edit -a $USER -t user access_bpf

# Set permissions on BPF devices (this needs to be done after each reboot)
sudo chmod g+rw /dev/bpf*
sudo chgrp access_bpf /dev/bpf*

# Log out and back in for group membership to take effect

Option 3: Homebrew Installation

If installed via Homebrew, the formula will provide detailed setup instructions:

brew tap domcyrus/rustnet
brew install rustnet
# Follow the caveats displayed after installation

Linux Permission Setup

On Linux, packet capture requires CAP_NET_RAW and CAP_NET_ADMIN capabilities.

Option 1: Run with sudo (Simplest)

# Build and run with sudo
cargo build --release
sudo ./target/release/rustnet

Option 2: Grant Capabilities (Recommended)

Grant specific network capabilities to the binary without full root privileges:

# Build the binary first
cargo build --release

# Grant network capabilities to the binary
sudo setcap cap_net_raw,cap_net_admin=eip ./target/release/rustnet

# Now run without sudo
./target/release/rustnet

For system-wide installation:

# If installed via package manager or copied to /usr/local/bin
sudo setcap cap_net_raw,cap_net_admin=eip /usr/local/bin/rustnet
rustnet

Option 3: Homebrew on Linux

# Install via Homebrew
brew install domcyrus/rustnet/rustnet

# Grant capabilities to the Homebrew-installed binary
sudo setcap cap_net_raw,cap_net_admin=eip $(brew --prefix)/bin/rustnet

# Run without sudo
rustnet

Windows Permission Setup

Windows support is currently limited, but when available:

RustNet will require Administrator privileges
Must install WinPcap or Npcap for packet capture
Run Command Prompt or PowerShell "As Administrator"

Verifying Permissions

To verify that permissions are set up correctly:

macOS

# Check BPF device permissions
ls -la /dev/bpf*

# Check group membership
groups | grep access_bpf

# Test without sudo
rustnet --help

Linux

# Check capabilities on the binary
getcap ./target/release/rustnet
# Should show: cap_net_raw,cap_net_admin=eip

# Test without sudo
rustnet --help

Troubleshooting Permission Issues

"Permission denied" errors

On macOS:

Ensure you're in the access_bpf group: groups | grep access_bpf
Check BPF device permissions: ls -la /dev/bpf0
Try running with sudo to confirm it's a permission issue
Log out and back in after group changes

On Linux:

Check if capabilities are set: getcap $(which rustnet)
Verify libpcap is installed: ldconfig -p | grep pcap
Try running with sudo to confirm it's a permission issue
Some systems require CAP_NET_BIND_SERVICE as well

"No suitable capture interfaces found"

Check available interfaces: ip link show (Linux) or ifconfig (macOS)
Try specifying an interface explicitly: rustnet -i eth0
Ensure the interface is up and has an IP address
Some virtual interfaces may not support packet capture

"Operation not permitted" with capabilities set

Capabilities may have been removed by system updates
Re-apply capabilities: sudo setcap cap_net_raw,cap_net_admin=eip $(which rustnet)
Some filesystems don't support extended attributes (capabilities)
Try copying the binary to a different filesystem (e.g., from NFS to local disk)

Security Best Practices

Use capabilities instead of sudo when possible (Linux)
Use group-based access instead of running as root (macOS)
Regularly audit which users have packet capture privileges
Consider network segmentation if running on production systems
Monitor log files for unauthorized usage

Remove capabilities when RustNet is no longer needed:

# Linux: Remove capabilities
sudo setcap -r /path/to/rustnet

# macOS: Remove from group
sudo dseditgroup -o edit -d $USER -t user access_bpf

Integration with System Monitoring

For production environments, consider:

Audit logging of packet capture access
Network monitoring policies and compliance requirements
User access reviews for privileged network access
Automated capability management in configuration management systems

This permissions setup ensures RustNet can capture packets while maintaining security best practices and principle of least privilege.

Contributing

Contributions are welcome! Please:

Fork the repository
Create a feature branch (git checkout -b feature/amazing-feature)
Commit your changes (git commit -m 'Add amazing feature')
Push to the branch (git push origin feature/amazing-feature)
Open a Pull Request

For Maintainers

For detailed information about the release process, see RELEASE.md.

Roadmap

For planned features and future improvements, see ROADMAP.md.

License

This project is licensed under the Apache License, Version 2.0 - see the LICENSE file for details.

Acknowledgments

Built with ratatui for the terminal UI
Packet capture powered by libpcap
Inspired by tools like tshark/wireshark/tcpdump, sniffnet, netstat, ss, and iftop
Some code is vibe coded (OMG) / may the LLM gods be with you