📡 netmon

A modern, beautiful CLI tool for network monitoring and process management

A beautifully designed network monitoring tool built with Go that provides an intuitive interface for viewing active ports, network interfaces, routing tables, and managing processes on Linux, macOS, and Windows.

Features • Installation • Usage • Commands

✨ Features

🔌 Network Monitoring

📋 Port Listing - Display all active TCP/UDP ports with detailed process metrics
- Process owner (username)
- CPU usage percentage
- Memory usage percentage
🌐 Network Interfaces - View network interface information with IP addresses
- IPv4 addresses by default
- IPv6 support with -a flag
- Filter interfaces with active IPs
🛣️ Routing Table - Display system routing information with smart filtering
- Native OS APIs (Netlink on Linux, BSD routing socket on macOS, Win32 API on Windows)
- Smart filtering (excludes /32 hosts, link-local, multicast, broadcast)
- Cross-platform compatible
🗺️ Traceroute - Trace network path to destination with animated loading
- Cross-platform support (traceroute/tracert)
- Beautiful table format with color-coded RTT values
- Real-time animated spinner during execution
📊 Network Statistics - View network statistics summary at a glance
- Connection counts (TCP/UDP)
- Listening ports count
- Network interfaces count
- Default gateway information
- Top processes by connection count
🌐 DNS Lookup - Perform DNS lookups with clean output
- Forward lookup (A, AAAA, CNAME, MX, NS, and TXT records)
- Reverse lookup (PTR records)
- Response time measurement
- No external dependencies (uses Go's net package)

🔍 Process Management

Smart Process Search - Find processes by PID, port, or name with automatic detection
- Provide a number to search by both PID and port simultaneously
- Provide a string to search by process name or command line substring
- Shows full command line (like ps -ef) for easy identification
- Displays all active ports used by the process
Process Shutdown - Safely terminate processes with interactive confirmation
Real-time Metrics - Monitor CPU and memory usage per process

🎨 User Experience

Beautiful UI - Modern terminal interface with color-coded output
Center-aligned Headers - Clean, organized table layouts
Optimized Columns - Compact display for better terminal compatibility
Automatic Sorting - Port listings sorted by port number for easy scanning
Shell Completion - Tab completion support for Bash, Zsh, and Fish
Fast & Lightweight - Built with Go for optimal performance

📦 Installation

🍺 Homebrew (macOS Recommended)

brew install zzzzseong/netmon/netmon

🐧 Linux - Quick Install Script

The easiest way to install on Linux:

# Install latest version
curl -fsSL https://raw.githubusercontent.com/zzzzseong/netmon/main/scripts/install.sh | bash

# Install specific version
curl -fsSL https://raw.githubusercontent.com/zzzzseong/netmon/main/scripts/install.sh | bash -s v1.5.0

The script automatically:

Detects OS and architecture (Linux AMD64/ARM64)
Installs traceroute dependency (required for traceroute command)
Downloads the latest version
Installs to /usr/local/bin
Installs shell completions (Bash, Zsh, Fish)
Verifies installation

After installation, you can immediately use netmon:

netmon ls        # List active ports
netmon ip        # Show network interfaces
netmon --help    # Show all commands

Note: If netmon is not found after installation, try opening a new terminal or run hash -r to refresh the command cache.

📥 Download Pre-built Binaries

Pre-built binaries are available in the Releases section.

For Linux:

netmon-linux-amd64.tar.gz (Intel/AMD 64-bit)
netmon-linux-arm64.tar.gz (ARM 64-bit)

For macOS:

netmon-darwin-amd64.tar.gz (Intel)
netmon-darwin-arm64.tar.gz (Apple Silicon)

For Windows:

netmon-windows-amd64.zip (Intel/AMD 64-bit)

Installation (Linux / macOS):

# Download and extract
tar -xzf netmon-<platform>-<arch>.tar.gz

# Install (optional)
sudo mv netmon /usr/local/bin/

# Verify executable permissions
chmod +x /usr/local/bin/netmon

Installation (Windows):

# Extract the zip file
Expand-Archive netmon-windows-amd64.zip -DestinationPath .

# Run directly
.\netmon.exe --help

# Or move to a directory in your PATH (optional, run as Administrator)
Move-Item netmon.exe C:\Windows\System32\netmon.exe

🔨 Build from Source

Prerequisites:

Go 1.25 or higher
traceroute command (for traceroute functionality)
- Linux: sudo apt-get install traceroute (Debian/Ubuntu) or sudo yum install traceroute (RHEL/CentOS)
- macOS: Usually pre-installed, or brew install traceroute
- Windows: Uses built-in tracert command

Linux / macOS:

# Clone the repository
git clone https://github.com/zzzzseong/netmon.git
cd netmon

# Build
go build .

# Install (optional)
sudo mv netmon /usr/local/bin/

Windows:

# Clone the repository
git clone https://github.com/zzzzseong/netmon.git
cd netmon

# Build (produces netmon.exe)
go build .

# Run directly
.\netmon.exe --help

# Or move to a directory in your PATH (optional, run as Administrator)
Move-Item netmon.exe C:\Windows\System32\netmon.exe

🚀 Usage

📋 List Active Ports

Display all active listening ports with detailed process information:

# Show TCP LISTEN connections only (default)
netmon ls

Output:

╭────────────┬─────────────────────┬────────────┬───────────┬───────────────────────────┬─────────────────┬───────────┬──────────╮
│  PROTOCOL  │    LOCAL ADDRESS    │   STATUS   │   PID     │       PROCESS NAME        │    USERNAME     │  CPU %    │  MEM %   │
├────────────┼─────────────────────┼────────────┼───────────┼───────────────────────────┼─────────────────┼───────────┼──────────┤
│ TCP        │ 127.0.0.1:8080      │ LISTEN     │ 12345     │ node                      │ jisung          │ 15.2%     │ 2.1%     │
│ TCP        │ *:3000              │ LISTEN     │ 23456     │ nginx                     │ jisung          │ 2.5%      │ 0.8%     │
╰────────────┴─────────────────────┴────────────┴───────────┴───────────────────────────┴─────────────────┴───────────┴──────────╯

# Include UDP connections with -a flag
netmon ls -a

Output:

╭────────────┬─────────────────────┬────────────┬───────────┬───────────────────────────┬─────────────────┬───────────┬──────────╮
│  PROTOCOL  │    LOCAL ADDRESS    │   STATUS   │   PID     │       PROCESS NAME        │    USERNAME     │  CPU %    │  MEM %   │
├────────────┼─────────────────────┼────────────┼───────────┼───────────────────────────┼─────────────────┼───────────┼──────────┤
│ TCP        │ 127.0.0.1:8080      │ LISTEN     │ 12345     │ node                      │ jisung          │ 15.2%     │ 2.1%     │
│ TCP        │ *:3000              │ LISTEN     │ 23456     │ nginx                     │ jisung          │ 2.5%      │ 0.8%     │
│ UDP        │ 127.0.0.1:53         │ NONE       │ 567       │ systemd-resolved          │ root            │ 0.1%      │ 0.3%     │
╰────────────┴─────────────────────┴────────────┴───────────┴───────────────────────────┴─────────────────┴───────────┴──────────╯

🔗 Show Active Connections

Display active ESTABLISHED TCP connections with owning process information:

netmon conn

Output:

╭────────────┬───────────────────────────┬───────────────────────────┬───────────┬─────────────────────────╮
│  PROTOCOL  │       LOCAL ADDRESS       │      REMOTE ADDRESS       │   PID     │         PROCESS         │
├────────────┼───────────────────────────┼───────────────────────────┼───────────┼─────────────────────────┤
│ TCP        │ 127.0.0.1:8080            │ 192.168.1.100:54321       │ 12345     │ node                    │
│ TCP        │ 10.0.0.15:5173            │ 142.250.206.206:443       │ 23456     │ chrome                  │
╰────────────┴───────────────────────────┴───────────────────────────┴───────────┴─────────────────────────╯

🌐 View Network Interfaces

Display network interfaces with IP addresses:

# Show IPv4 addresses only (default)
netmon ip

Output:

╭──────────────┬──────────────────────────────────────────┬──────────────────────┬─────────────┬─────────────╮
│  INTERFACE   │                IP ADDRESS                │     MAC ADDRESS      │  STATUS     │  MTU        │
├──────────────┼──────────────────────────────────────────┼──────────────────────┼─────────────┼─────────────┤
│ en0          │ 192.168.1.100/24                         │ a4:83:e7:5c:5d:3e    │ UP          │ 1500        │
│ lo0          │ 127.0.0.1/8                              │ N/A                  │ UP          │ 16384       │
╰──────────────┴──────────────────────────────────────────┴──────────────────────┴─────────────┴─────────────╯

# Show all addresses including IPv6
netmon ip -a

🛣️ View Routing Table

Display system routing information with smart filtering:

netmon route

Output:

╭───────────────────────────┬───────────────────────────┬───────────────────────────┬───────────────────────────┬──────────────────────────╮
│  DESTINATION              │  GATEWAY                  │  INTERFACE                │  METRIC                   │  SOURCE                  │
├───────────────────────────┼───────────────────────────┼───────────────────────────┼───────────────────────────┼──────────────────────────┤
│ default                   │ 172.16.3.254              │ en0                       │ -                         │ 172.16.0.99              │
│ 172.16.0.0/22             │ -                         │ en0                       │ -                         │ 172.16.0.99              │
│ 10.10.0.0/24              │ -                         │ docker0                   │ -                         │ 10.10.0.1                │
╰───────────────────────────┴───────────────────────────┴───────────────────────────┴───────────────────────────┴──────────────────────────╯

🗺️ Trace Route to Host

Trace the network path to a destination with animated loading indicator:

netmon traceroute <host>

Example:

netmon traceroute google.com

Output:

◐ Tracing route to google.com...
╭──────────┬──────────────────────────────────────────┬──────────────┬──────────────┬──────────────╮
│  HOP     │                   HOST                   │    RTT 1     │    RTT 2     │    RTT 3     │
├──────────┼──────────────────────────────────────────┼──────────────┼──────────────┼──────────────┤
│ 1        │ 192.168.1.1                              │ 2.5 ms       │ 2.3 ms       │ 2.1 ms       │
│ 2        │ 10.0.0.1                                 │ 15.2 ms      │ 14.8 ms      │ 15.0 ms      │
│ 3        │ 172.217.160.46                           │ 25.3 ms      │ 24.9 ms      │ 25.1 ms      │
╰──────────┴──────────────────────────────────────────┴──────────────┴──────────────┴──────────────╯

📊 View Network Statistics

Display network statistics summary:

netmon stats

Output:

╭────────────────────────────────────────────────────────────╮
│                                                            │
│  Network Summary                                           │
│                                                            │
│  Active TCP Connections:       150                         │
│  Active UDP Connections:       0                           │
│  Listening Ports:              42                          │
│  Network Interfaces:           19                          │
│  Default Gateway:              192.168.1.1                 │
│                                                            │
│  Top Processes by Connections:                             │
│    • chrome (25 connections)                               │
│    • node (12 connections)                                 │
│    • docker (8 connections)                                │
│                                                            │
╰────────────────────────────────────────────────────────────╯

🌐 Perform DNS Lookup

Lookup DNS records for a domain or IP address:

Domain lookup returns A, AAAA, CNAME, MX, NS, and TXT records when available
IP lookup returns PTR records for reverse DNS

# Forward lookup (domain to IP)
netmon dns google.com

Output:

🔍 DNS Lookup: google.com

╭───────────────┬──────────────────────────────────────────────────────────────╮
│     TYPE      │                            VALUE                             │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ A             │ 142.250.206.206                                              │
│ AAAA          │ 2404:6800:400a:813::200e                                     │
│ CNAME         │ google.com.                                                  │
│ MX            │ smtp.google.com. (priority: 10)                              │
│ NS            │ ns1.google.com.                                              │
│ TXT           │ v=spf1 include:_spf.google.com ~all                          │
╰───────────────┴──────────────────────────────────────────────────────────────╯

Response Time: 6ms

# Reverse lookup (IP to domain)
netmon dns 8.8.8.8

Output:

🔍 DNS Lookup: 8.8.8.8

╭───────────────┬──────────────────────────────────────────────────────────────╮
│     TYPE      │                            VALUE                             │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ PTR           │ dns.google.                                                  │
╰───────────────┴──────────────────────────────────────────────────────────────╯

Response Time: 3ms

🔍 Find Process by PID, Port, or Name

Find processes using a smart search that automatically detects PID, port, or process name:

netmon find <pid|port|name>

How it works:

Provide a number, and find automatically searches by both PID and port
Provide a string, and find searches by process name or command line substring
If both match, both results are shown (duplicates removed)
If only one matches, only that result is displayed
Shows full command line (like ps -ef) for easy process identification
Displays active ports (LISTEN) and active connections (ESTABLISHED) for the found process

Examples:

# Search by port 8080
netmon find 8080

# Search by PID 8922
netmon find 8922

# Search by process name
netmon find nginx

# If PID 8080 exists AND port 8080 is in use, both results shown
netmon find 8080

Output:

🔍 Found by Port: 8080

╭──────────────────────────────────────────────────╮
│ PID:        12345                               │
│ Name:       node                                │
│ Status:     [sleep]                             │
│                                                 │
│ Command:                                        │
│   /usr/bin/node /path/to/server.js              │
│                                                 │
│ Active Ports:                                   │
│   • 127.0.0.1:8080 (TCP)                        │
│                                                 │
│ Active Connections:                             │
│   • 127.0.0.1:8080 → 192.168.1.100:54321       │
╰──────────────────────────────────────────────────╯

Smart search that works with both PIDs and ports - shows active ports and connections!

🛑 Shutdown Process

Safely shutdown a process with interactive confirmation:

netmon shutdown <pid>

Example:

netmon shutdown 12345

The command will:

📊 Display detailed process information (PID, name, status, active ports)
❓ Show an interactive prompt for confirmation
✅ Safely shutdown the process if confirmed

Interactive Prompt:

⚠️  Shutdown Confirmation for PID 12345

╭─────────────────────────────────────╮
│ PID:        12345                   │
│ Name:       nginx                   │
│ Status:     [S]                     │
│                                     │
│ Active Ports:                       │
│   • 0.0.0.0:8080 (TCP)             │
╰─────────────────────────────────────╯

Are you sure you want to shutdown this process?
▸ ✓ Yes, shutdown
  ✗ No, cancel

🔄 Update netmon

Upgrade netmon to the latest version without re-running the install script:

netmon update

Output:

# Already on the latest version
Checking for updates...
Already up to date (v1.6.0)

# Update available
Checking for updates...
Updating v1.5.0 → v1.6.0
Downloading netmon-linux-amd64.tar.gz...
Verifying checksum...
Installing to /usr/local/bin/netmon...
Updated to v1.6.0

Note: If the install directory (e.g. /usr/local/bin) requires root access, netmon automatically retries with sudo.

📚 Commands

Command	Description	Usage	Flags
`ls`	List all active ports with process metrics	`netmon ls`	`-a` (include UDP)
`ip`	Show network interfaces	`netmon ip`	`-a` (show IPv6)
`route`	Display routing table with smart filtering	`netmon route`	-
`stats`	Display network statistics summary	`netmon stats`	-
`dns`	Perform DNS lookup	`netmon dns <domain	ip>`
`conn`	Show active ESTABLISHED connections	`netmon conn`	-
`find`	Find process by PID, port, or name (auto-detects)	`netmon find <pid	port
`shutdown`	Shutdown a process	`netmon shutdown <pid>`	-
`traceroute`	Trace route to network host	`netmon traceroute <host>`	-
`version`	Show version information	`netmon version`	-
`update`	Update netmon to the latest version	`netmon update`	-
`help`	Show help information	`netmon help`	-

🎯 Use Cases

🔧 Port Conflict Resolution - Quickly find which process is using a port (smart PID/port search with active connections)
📊 Network Monitoring - Monitor network statistics and connections with real-time metrics
🛡️ Process Management - Safely terminate processes with confirmation
💻 Development - Check if your development server port is available
🌐 Network Debugging - View network interfaces and routing information
📈 Performance Monitoring - Track CPU and memory usage per process

🆕 What's New in v1.6.6

Released: 2026-05-26

📄 Watch Mode Pagination - When table height exceeds terminal height, output is automatically split into pages. Navigate with [ / ] or left/right arrow keys. Column headers and borders are preserved on every page

Previous Releases

v1.6.5:

🔧 Watch Mode Flicker Fix - Alternate screen cleared once on entry, in-place overwriting on each refresh

v1.6.4:

🖥️ Watch Mode Alternate Screen - Switched to terminal alternate screen buffer, preventing scroll corruption when table height exceeds terminal height
⚡ Default Interval 1s - Watch mode refresh interval default changed from 2s to 1s

v1.6.3:

🐛 CPU% Always 0 Fix - CPU usage now shows accurate values in watch mode
🖥️ Watch Mode Screen Fix - Screen cleared once on entry so prior shell history no longer bleeds through

v1.6.2:

🔧 Watch Mode Flicker Fix - Eliminated screen flicker in watch mode by overwriting in place instead of clearing the full screen
💡 Watch Mode Help - Watch mode usage guide now shown in netmon help output

v1.6.1:

👁️ Watch Mode - --watch / -w flag added to ls, conn, stats, ip, route commands. Refresh interval configurable with -n (default: 2s)

v1.6.0:

🔄 Self-Upgrade Command - netmon update upgrades netmon in place with checksum verification, no need to re-run the install script
🐛 Install Script Fix - Checksum verification no longer fails on Linux (tarball filename now matches SHA256SUMS entry)

v1.5.0:

🪟 Windows Installation Guide - Full Windows download and installation documentation added
🔍 Find Command Fix - Full command line now correctly displayed (ps -ef style) when finding processes
🌐 DNS Enhancement - Underscore-containing domains (SRV, DMARC records like _dmarc.google.com) now supported
🛡️ Route Filtering - IPv6 routes properly excluded from routing table output on all platforms
🔧 Cross-Platform Reliability - Resolved Windows CI failures (go vet unsafe.Pointer, binary extension)
⚡ Signal Handling - Traceroute cancellation signal handling split by platform (Unix: SIGTERM+Interrupt, Windows: Interrupt only)

v1.4.0:

📊 Network Statistics Command - Quick overview of network activity with connection counts, listening ports, and top processes
🌐 DNS Lookup Command - Fast DNS lookups (forward and reverse) with response time measurement
🔍 Enhanced Find Command - Now displays active connections for found processes
🎨 Enhanced Formatting - Beautiful table layouts for all new commands
⚡ Performance Improvements - Optimized connection filtering and DNS lookup performance

v1.2.2:

🔍 Enhanced Find Command - Smart search that automatically detects PID or port, shows full command line
📋 Automatic Port Sorting - Port listings are now automatically sorted by port number
🛑 Improved Shutdown UI - Better confirmation prompts and styled success/cancel messages
🏗️ Code Quality Improvements - Following Go best practices with comprehensive documentation
🧪 Enhanced Testing - Added test coverage for multiple packages including benchmarks

v1.2.1:

🎨 Custom Help Output Restored
🧹 Completion Command Cleanup
📁 Code Organization improvements

Shell Completion

Shell completion is automatically installed when you use the install script or Homebrew.

Linux Installation (via install script):

# Install netmon (completions are automatically installed to system directories)
curl -fsSL https://raw.githubusercontent.com/zzzzseong/netmon/main/scripts/install.sh | bash

# Completions are installed to system directories:
# - Bash: /etc/bash_completion.d or /usr/local/etc/bash_completion.d
# - Zsh: /usr/share/zsh/site-functions or /usr/local/share/zsh/site-functions
# 
# Most Linux distributions work without additional configuration.
# Just restart your shell. If completion doesn't work:
# - Bash: Ensure bash-completion package is installed
# - Zsh: Ensure compinit is enabled in your ~/.zshrc

macOS Installation (via Homebrew):

# Homebrew automatically installs completions
brew install zzzzseong/netmon/netmon

# Add to ~/.zshrc (shown in installation caveats):
if type brew &>/dev/null; then
  FPATH=$(brew --prefix)/share/zsh/site-functions:$FPATH
  autoload -Uz compinit
  compinit
fi

# Then restart your shell or run:
source ~/.zshrc

📜 For detailed changelog and previous versions, see GitHub Releases

🛠️ Tech Stack

Language: Go 1.25+
Core Dependencies:
- github.com/shirou/gopsutil/v3 - System and process utilities
- github.com/charmbracelet/lipgloss - Terminal styling
- github.com/manifoldco/promptui - Interactive prompts
Routing System:
- github.com/vishvananda/netlink - Linux netlink interface
- golang.org/x/net/route - BSD routing socket interface
- golang.org/x/sys/windows - Windows system calls

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

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

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🔗 Links

GitHub: https://github.com/zzzzseong/netmon
Issues: https://github.com/zzzzseong/netmon/issues
Releases: https://github.com/zzzzseong/netmon/releases

Made with by zzzzseong

⭐ Star this repository if you find it helpful!

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.gitignore		.gitignore
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LICENSE		LICENSE
README.md		README.md
go.mod		go.mod
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📡 netmon

✨ Features

🔌 Network Monitoring

🔍 Process Management

🎨 User Experience

📦 Installation

🍺 Homebrew (macOS Recommended)

🐧 Linux - Quick Install Script

📥 Download Pre-built Binaries

🔨 Build from Source

🚀 Usage

📋 List Active Ports

🔗 Show Active Connections

🌐 View Network Interfaces

🛣️ View Routing Table

🗺️ Trace Route to Host

📊 View Network Statistics

🌐 Perform DNS Lookup

🔍 Find Process by PID, Port, or Name

🛑 Shutdown Process

🔄 Update netmon

📚 Commands

🎯 Use Cases

🆕 What's New in v1.6.6

Previous Releases

Shell Completion

🛠️ Tech Stack

🤝 Contributing

📄 License

🔗 Links

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📡 netmon

✨ Features

🔌 Network Monitoring

🔍 Process Management

🎨 User Experience

📦 Installation

🍺 Homebrew (macOS Recommended)

🐧 Linux - Quick Install Script

📥 Download Pre-built Binaries

🔨 Build from Source

🚀 Usage

📋 List Active Ports

🔗 Show Active Connections

🌐 View Network Interfaces

🛣️ View Routing Table

🗺️ Trace Route to Host

📊 View Network Statistics

🌐 Perform DNS Lookup

🔍 Find Process by PID, Port, or Name

🛑 Shutdown Process

🔄 Update netmon

📚 Commands

🎯 Use Cases

🆕 What's New in v1.6.6

Previous Releases

Shell Completion

🛠️ Tech Stack

🤝 Contributing

📄 License

🔗 Links

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