How it works

Built so you can check, not just trust

SubnetSlinger is a desktop app. The tools run on your computer, the results are saved on your computer, and nothing about your network is sent to us. This page shows how it's put together. The Check it yourself guide shows you how to prove it.

The picture

Your computer

The app

60+ tools, the Deputy and Posse AI, local servers, the Console.

Your data

Results, inventory, incidents, exports, and the Vault (encrypted), all on this machine.

Local AI (optional)

Ollama running on this machine. Your questions and answers never leave it.

tools you run, against devices you choose

Your network

Switches, routers, servers, firewalls. SubnetSlinger talks to them only when you run a tool against them, or turn on the Auto-poll monitor. The one thing it checks by itself is a ping to your own default gateway when Home opens (Windows and Linux), to show whether your network is up.

only when you sign in, open a screen that needs it, press a button, or at the launch-time license checks listed on the Privacy page

License service

Sign-in code and license check. Holds your email, license and purchase records, and sign-in records. Never your network data.

Your AI provider

Only when you use the Deputy or Posse with a cloud provider and your own key. Secret-shaped text is masked first (a pattern match, not a guarantee).

Lookups

Public IP, WHOIS, speed test, MAC vendor, DNS-over-HTTPS and the Network Experience monitor when you run them (or the Deputy, or an AI app you connect over MCP, runs one for you), and our public model and price list when the Deputy opens with a cloud provider.

What never happens: no telemetry, no analytics, no usage tracking, no background scans (monitors run only if you turn them on), no copy of your results on our servers. Nothing of ours sits in the path of your work: the only things the Windows and Linux app fetches from us are the license check and a public price list. The Mac app also reads our update feed when you choose Check for Updates.

Every connection is listed, in one place

Every outside host the Windows and Linux app can contact, what it's for, when it happens and what's sent is in one table: the firewall allowlist on the Trust page. The Privacy page has the line-by-line detail, and the macOS section lists the Mac app's own lookups. The free tier needs no account and works with no internet at all.

No internet required

The tools, the local servers, the Console, your inventory and incidents all work with no internet connection. You need the internet only for an outside AI vendor, for signing in and the license check-in (a Pro license keeps working up to 30 days offline after its last check), and for tools whose job is to reach the internet (speed test, WHOIS, public IP).

AI is optional, and it only looks

Every tool works without AI. No question goes to an AI provider until you ask one. With a key set, opening the Deputy also fetches that provider's model list.
On this machine: an Ollama model running on your desktop. Your questions and answers never leave it (lookup tools the Deputy runs for you still reach the internet, as listed on the Trust page).
Your company's model: point the Deputy at your own OpenAI-compatible endpoint or Ollama server.
An outside vendor: Anthropic, an OpenAI-compatible service or Google Gemini, with your own key. Secret-shaped text is masked before it's sent (a pattern match for well-known secret shapes, not a guarantee; use local Ollama for anything truly sensitive).
It can look; only you can touch. The Deputy's built-in network tools read; they don't change your devices. The one exception is a third-party MCP server you connect and deliberately switch to "writes" (off by default).
A spend cap, on by default: $10 a day and $2 per Posse run. A run stops at the cap (it may finish the step it's on), and Stop works mid-run.
Your company's AI assistant: it can call SubnetSlinger's 17 read-only diagnostics through MCP. The MCP server runs only when that AI app starts it and logs every request on your machine. In 1.3 it has no on/off switch inside SubnetSlinger, so connect only AI apps you trust.

Safety built into the Console

Read-only mode is on by default. It holds config changes and destructive lines (reload, reboot, write erase, format, factory reset), including one hidden inside a paste, and nothing is sent. With Read-only off, changes run normally, and a line that can reload or wipe a device sets off a loud on-screen warning as it's sent; the device's own confirm prompt is the final gate. You make every change; the app never changes a device on its own.

Your license is checked, your network is not

Pro is a signed license (an ES256 signature checked on your machine against a key built into the app), so editing the license file grants nothing. Pro needs a check-in every 30 days and a trial every 14; on Windows and Linux, opening the Account screen does it. So Pro keeps working up to 30 days without internet after its last check. The license service holds your email, your license and purchase records, and sign-in records (the IP address and app each sign-in came from). Never your network data. Exactly when it checks.

Check that your download is the one we published

Windows comes from the Microsoft Store, which signs it. macOS is notarized by Apple. The Linux and macOS downloads are also signed with our offline GPG key and ship checksums and a component list (SBOM). Steps to verify are on the Setup page.

Built and lab-checked the real way

SubnetSlinger is built by a small team led by Alex Smith, a network, network security and software engineer with 30+ years in the field. It's lab-checked against real Cisco switches and real devices, not just simulators, with a person in the loop. More about who builds it.

Open about problems

We test the app with our own code and security reviews, using free tools, and we publish security advisories when something needs your attention (the first, SS-2026-01, covers the capture permission in the Linux tarball, found in our own review). Reports go to sheriff@subnetslinger.com.