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Netfox 0.19.0 — what a certificate says about itself

Netfox now reads the certificate a TLS port presents and says plainly when it has expired, is about to, or was signed by itself.

Giovambattista Fazioli
Senior Full-stack Engineer, Lead Developer
·
2 min read
Netfox 0.19.0 — what a certificate says about itself

Every home network has a few of them: the NAS admin page, the printer's web UI, the router itself, a Home Assistant box. They all speak TLS, they all present a certificate, and almost nobody ever looks at it — until a browser refuses to open one and you are left guessing whether the device is broken, misconfigured, or just doing what home devices do.

Netfox 0.19.0 reads that certificate for you and says what it says.

What you will see

Open a device, pick a port that speaks TLS from the first byte — 443, 8443, 993, 995 and their kind — and press Read certificate. The card underneath shows who the certificate was issued to, who issued it, and when it expires. Then it states the two things worth knowing without making you work them out:

  • Expired. Named as such, with the date.

  • Signed by itself. Nothing vouches for it. That is normal on a home device that generated its own, and worth a second look anywhere else — and the card says exactly that, so the verdict arrives with its context.

Two more lines appear only when they matter: a certificate that runs out within three weeks, and one that is not valid yet — which on a home network almost always means the clock on the device is wrong, not the certificate.

The service lookup on an open port. The certificate card sits right beside it, behind the same privacy switch.

The service lookup on an open port. The certificate card sits right beside it, behind the same privacy switch.

What it does not do

It does not start anything on its own. The read happens when you press the button, and only if the same privacy setting that governs looking up service info is on. Ports that start in plain text and upgrade to TLS later are deliberately left alone: a greeting aimed at them is not a greeting.

And in Demo Mode the card is hidden entirely. A certificate's name on a home network is very often the device's hostname, which is exactly the kind of thing Demo Mode exists to keep off a screenshot.

A correction

The What's New panel of 0.18.1 said nothing in the app itself had changed. That was wrong, and the panel inside the app was the one place it could not be fixed on the day. Besides the signing fix, 0.18.1 also graded the radio's headroom by the same threshold the Wi-Fi tool uses, named the interface the route leaves through, and rewrote two sentences of the link panel. This release's panel says so.


Netfox is free, a universal binary (Apple Silicon + Intel), runs on macOS 15.6+, and is signed and notarized.

Netfox for macOS — Website: https://netfox.app · Download: https://netfox.app/download

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Giovambattista Fazioli
Giovambattista Fazioli

Senior Full-stack Engineer, Lead Developer

Italian Senior Full-stack Engineer and Lead Developer on the Cloud team at Namecheap. I build developer tools, React/Mantine UI components and native macOS apps — mostly open source. I work across TypeScript, Next.js, Go and SwiftUI, and I've been coding since the Commodore/Assembly days. Creator of WP Bones and 25+ Mantine extensions, and maintainer of the Undolog open-source studio.

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