NetLens

Portable LAN scanner for small business networks. Native Windows · C++20 · Single .exe · No installer · No telemetry · No cloud.

Maintained by 3389 Software Outsourcing. Open source under the MIT License — see LICENSE.txt for terms and NOTICE.txt for third-party attributions (IEEE OUI registry).

Latest binary: Releases page → NetLens.exe Product page: 3389.ro/tools/netlens

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What it does

NetLens maps your subnet, identifies who's on it, identifies what's exposed, and produces a consultant-quality HTML report. It is built for IT admins, consultants and small businesses who want a fast LAN sweep and a clean deliverable to attach to an email — without dragging in a full security-audit toolchain or a vendor's installer.

NetLens is not a vulnerability scanner. It enumerates hosts and surfaces exposure hints; it never asserts a confirmed CVE on any host.

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Highlights (1.5)

• One 2.5 MB self-contained .exe. Native Win32 + GDI. Static CRT — no vcruntime / msvcp DLL dependency. PerMonitorV2 DPI awareness. Loads on Windows 7 / 8 / 8.1 / 10 / 11 / Server 2012+.
• Security findings. Curated CVE / EOL heuristics derived from observable banners, fingerprints and version hints — surfaced in the details pane and the HTML report. Heuristic hints, never a confirmed CVE.
• Device Type + exact Model. A dedicated Model column (grid, HTML and CSV) reads the precise model only from manufacturer-driven, read-only endpoints — HPE iLO, TP-Link, MikroTik RouterOS, VMware ESXi, Ubiquiti, Netgear, Yealink, Synology / Thecus — and never shows a raw page title.
• SMB dialect + shares. Direct SMB negotiation reports SMB 1.0 / 2.x / 3.x, with anonymous share enumeration where the host permits it.
• Live host grid. Sortable on every column; selection follows the IP across mid-scan re-sorts and end-of-scan reshuffles.
• Eight UDP discovery probes per online host (Full Common preset and above): NBNS / NTP / SSDP / mDNS / SQL Browser / DNS / LLMNR / IPMI. One shared select() loop with a 600 ms global budget; source- IP-verified responses (drops LAN spoofs).
• Printer SNMP. SNMPv2c Printer-MIB walker reports vendor + model
  • serial + per-cartridge supply levels with colour-coded progress bars. Surfaces both in the GUI and in the HTML report.
• Real-time pill state. Ready · Scanning X% · Cancelling… · Cancelled · X% · Done · Error.
• Per-host details pane. Identity / inferred OS + device hint / web-UI brand / open TCP ports + service + version annotation / UDP discovery responses / risk hints / recommended actions. Each field has a copy affordance, plus a single "Copy report" button that emits a plain-text block ready to paste into a ticket.
• HTML export. Single self-contained file (embedded CSS, no CDN). Offline hosts hidden by default with an inline note; per-printer supply cards; per-host UDP discovery cards.
• CSV export with the same data, UTF-8 BOM, RFC-4180-escaped.
• No telemetry, no cloud, no auto-update, no registry writes, no installer, no admin rights, no %APPDATA% footprint.

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Scan modes

Mode	ICMP-online hosts	ICMP-silent hosts
Deep (default)	Full TCP scan + DNS + MAC + service fingerprint	Full TCP scan against the configured port list. Catches Windows boxes that block ICMP echo (SMB default) and devices that drop ICMP on purpose.
Fast	Full TCP scan + DNS + MAC	Probe only 26 discovery ports. If any answers, mark online via TCP fallback; otherwise mark offline.
Discovery-only	DNS + MAC only — no TCP	Marked offline.

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Port presets

Preset	Ports
Quick	61 ports — fastest, web + remote-access + common shares
Standard (default)	132 ports — daily LAN inventory
Full Common	231 ports — adds DB / mgmt / VoIP / IoT / dev tooling
All Ports — Fast	1 – 65535 (Fast mode)
All Ports — Deep	1 – 65535 (Deep mode)
Custom	Whatever you type into the toolbar's Ports box

UDP discovery runs on Full Common / All Ports / Custom presets. Printer SNMP runs on all presets except Quick (it stops at the sysDescr GET so vendor + model still come through; the prtMarkerSupplies walk is skipped).

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Repo layout

NetLens/
├── CHANGELOG.md
├── CMakeLists.txt
├── LICENSE.txt
├── NOTICE.txt
├── README.md
├── SECURITY.md
├── VERSION                          ← single source of truth (1.5.14)
├── app.manifest
├── app.rc
├── build.ps1                        ← one-shot Configure + Build
├── docs/
│   └── ARCHITECTURE.md
├── engine/                          ← C++ scan engine (static lib)
│   ├── CMakeLists.txt
│   ├── include/
│   │   └── netlens_engine.h         ← C ABI surface
│   └── src/
│       ├── ffi.cpp
│       ├── core/                    ← NetworkScanner, PortScanner,
│       │                              EnrichmentEngine, WebUiProbe, …
│       └── …
├── resources/
│   ├── app.ico
│   └── 3389-logo.bmp
├── src/                             ← Native Win32 UI
│   ├── App.cpp / App.h              ← engine bridge + filter / sort state
│   ├── MainWindow.cpp / .h
│   ├── Theme.cpp / .h
│   ├── Dpi.cpp / .h                 ← runtime-resolved DPI helpers
│   ├── Capture.cpp / .h             ← Ctrl+T full-UI screenshot
│   ├── Controls/                    ← StatCard, HostTable, DetailsPanel
│   └── Dialogs/                     ← About, Settings, Adapters, PortLists
└── tools/                           ← dev helpers (PowerShell)

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Build

Prerequisites:

• Visual Studio 2022 (Desktop development with C++) or the matching Build Tools (cl.exe on PATH).
• CMake 3.20+.

One-shot Release build:

.\build.ps1

Output:

build\bin\Release\NetLens.exe        ~2.5 MB

If Z:\Release exists the script also copies a versioned mirror as Z:\Release\NetLens_<version>.exe.

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License

MIT — see LICENSE.txt. Third-party attributions in NOTICE.txt (IEEE OUI registry, Windows system APIs).