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What the sensor does

The NextPKI sensor is a single static binary that runs inside your network, finds TLS certificates and reports their metadata. It exists because the certificates that hurt you are the ones nobody wrote down: the expired one on an appliance, the self-signed one on a printer, the forgotten host still serving traffic.

Mode Protocols
Direct TLS HTTPS, SMTPS (465), IMAPS (993), POP3S (995)
STARTTLS upgrade SMTP (25, 587), IMAP (143), POP3 (110)

Targets can be single hosts, host:port pairs, or IPv4 CIDR ranges, with include and exclude lists. For each service that completes a handshake, the sensor extracts the certificate chain, fingerprint, issuer, subject, SANs and validity window.

This list is the point of publishing the source - you can verify all of it.

  • It never sees private keys. The sensor reads what any TLS client sees during a handshake. Private keys of the scanned services stay on their hosts.
  • It reads no application data. The handshake completes, the chain is read, the connection closes. No HTTP bodies, no mail contents, no payloads.
  • It does not scan what you did not ask for. There is no opportunistic sweeping beyond the configured target list.

Concurrency is governed by a profile, and the default is deliberately timid - a discovery agent that takes down a customer network is a defect, not a performance feature.

Profile Concurrent connections
conservative (default) 16
standard 64
aggressive 256

Start with conservative. Raise it only after a full sweep has run cleanly and you know how your network reacts.

Each sensor holds its own mTLS client certificate, obtained once during install. Reports are attributed to that identity, which is how NextPKI knows which tenant - and which sensor - a finding came from. There is no shared API key across sensors.

Source available, not open source. The sensor is licensed under the PolyForm Internal Use License 1.0.0 plus additional grants from Datargo GmbH. Please do not describe it as open source.

You may You may not
Read, review and audit the source Redistribute the software
Publish review findings, including code excerpts Sublicense or transfer your license
Build it yourself and run your own builds Embed it in a product you supply
Run it for your own internal business operations
Run it on a client’s behalf, if you are an MSP, integrator or NextPKI partner and that client is entitled to use NextPKI

The full terms, including the exact wording of the additional grants, are in LICENSE in the repository. For anything beyond the left column - redistribution in particular - contact legal@datargo.com.

The point of publishing the source is that you do not have to trust what this page claims the sensor sends. You can check.