Show HN: Whosthere: A LAN discovery tool with a modern TUI, written in Go

Local Area Network discovery tool with a modern Terminal User Interface (TUI) written in Go. Discover, explore, and understand your LAN in an intuitive way.

Whosthere performs unprivileged, concurrent scans using mDNS and SSDP scanners. Additionally, it sweeps the local subnet by attempting TCP/UDP connections to trigger ARP resolution, then reads the ARP cache to identify devices on your Local Area Network. This technique populates the ARP cache without requiring elevated privileges. All discovered devices are enhanced with OUI lookups to display manufacturers when available.

Whosthere provides a friendly, intuitive way to answer the question every network administrator asks: "Who's there on my network?"

• Modern TUI: Navigate and explore discovered devices intuitively.
• Fast & Concurrent: Leverages multiple discovery methods simultaneously.
• No Elevated Privileges Required: Runs entirely in user-space.
• Device Enrichment: Uses OUI lookup to show device manufacturers.
• Integrated Port Scanner: Optional service discovery on found hosts (only scan devices with permission!).
• Daemon Mode with HTTP API: Run in the background and integrate with other tools.
• Theming & Configuration: Personalize the look and behavior via YAML configuration.

brew tap ramonvermeulen/whosthere
brew install whosthere

Or with Go:

go install github.com/ramonvermeulen/whosthere@latest

Or build from source:

git clone https://github.com/ramonvermeulen/whosthere.git
cd whosthere
make build

Run the TUI for interactive discovery:

Run as a daemon with HTTP API:

whosthere daemon --port 8080

Additional command line options can be found by running:

Whosthere is supported on the following platforms:

• Linux
• macOS
• Windows (maybe in the future, contributions welcome!)

Whosthere can be configured via a YAML configuration file. By default, it looks for the configuration file in the following order:

• Path specified in the WHOSTHERE_CONFIG environment variable (if set)
• $XDG_CONFIG_HOME/whosthere/config.yaml (if XDG_CONFIG_HOME is set)
• ~/.config/whosthere/config.yaml (otherwise)

When not running in TUI mode, logs are also written to the console output.

Example of the default configuration file:

# How often to run discovery scans
scan_interval: 20s

# Maximum duration for each scan
# If you set this too low some scanners or the sweeper might not complete in time
scan_duration: 10s

# Splash screen configuration
splash:
  enabled: true
  delay: 1s

# Theme configuration
theme:
  # Configure the theme to use for the TUI, complete list of available themes at:
  # https://github.com/ramonvermeulen/whosthere/tree/main/internal/ui/theme/theme.go
  # Set name to "custom" to use the custom colors below
  # For any color that is not configured it will take the default theme value as fallback
  name: default

  # Custom theme colors (uncomment and set name: custom to use)
  # primitive_background_color: "#000a1a"
  # contrast_background_color: "#001a33"
  # more_contrast_background_color: "#003366"
  # border_color: "#0088ff"
  # title_color: "#00ffff"
  # graphics_color: "#00ffaa"
  # primary_text_color: "#cceeff"
  # secondary_text_color: "#6699ff"
  # tertiary_text_color: "#ffaa00"
  # inverse_text_color: "#000a1a"
  # contrast_secondary_text_color: "#88ddff"

# Scanner configuration
scanners:
  mdns:
    enabled: true
  ssdp:
    enabled: true
  arp:
    enabled: true

# Port scanner configuration
port_scanner:
  timeout: 5s
  # List of TCP ports to scan on discovered devices
  tcp: [21, 22, 23, 25, 80, 110, 135, 139, 143, 389, 443, 445, 993, 995, 1433, 1521, 3306, 3389, 5432, 5900, 8080, 8443, 9000, 9090, 9200, 9300, 10000, 27017]

# Uncomment the next line to configure a specific network interface - uses OS default if not set
# network_interface: lo0

When running Whosthere in daemon mode, it exposes an very simplistic HTTP API with the following endpoints:

Theme can be configured via the configuration file, or at runtime via the CTRL+t key binding. A complete list of available themes can be found here, feel free to open a PR to add your own theme!

Example of theme configuration:

When the name is set to custom, the other color options can be used to create your own custom theme.

Logs are written to the application's state directory:

• $XDG_STATE_HOME/whosthere/app.log (if XDG_STATE_HOME is set)
• ~/.local/state/whosthere/app.log (otherwise)

When not running in TUI mode, logs are also output to the console.

For clipboard functionality to work:

Runtime requirements:

• Linux (X11): X11 client library (e.g., libx11-6 on Ubuntu, libX11 on Fedora/Arch, often pre-installed).
• Linux (Wayland): Not natively supported. May require XWayland.
• macOS/Windows: No dependencies.

Build requirements (when compiling from source):

• Linux: X11 development package (libx11-dev, libX11-devel, or libx11)

Whosthere is intended for use on networks where you have permission to perform network discovery and scanning, such as your own home network. Unauthorized scanning of networks may be illegal and unethical. Always obtain proper authorization before using this tool on any network.

Contributions and suggestions such as feature requests, bug reports, or improvements are welcome! Feel free to open issues or submit pull requests on the GitHub repository. Please make sure to discuss any major changes on a Github issue before implementing them.