github.com/samuelb/ssl_pubkey_fingerprint_exporter

SSL public key fingerprint exporter

This Prometheus exporter allows you to monitor the public key fingerprints of your SSL certificates.

Building

make

The created binaries will and up in the folder dist/.

Docker

docker pull basa/ssl-pubkey-fingerprint-exporter
docker run -p 3000:3000 basa/ssl-pubkey-fingerprint-exporter

Metrics

# HELP ssl_pubkey_fingerprint SSL certificate publickey SHA-256 fingerprint
# TYPE ssl_pubkey_fingerprint gauge
ssl_pubkey_fingerprint{fingerprint="base64encodedsha256sumofbinarypublickey=",target="example.com:443"} 1

Prometheus

Scrape configuration

scrape_configs:
  - job_name: "ssl-pubkey-fingerprint-exporter"
    metrics_path: /probe
    static_configs:
      - targets:
          - example.com:443
          - https://example.org
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_target]
        target_label: instance
      - target_label: __address__
        replacement: ssl-pubkey-fingerprint-exporter:3000

Example PromQL query

absent(ssl_pubkey_fingerprint{fingerprint="base64encodedsha256sumofbinarypublickey",target="example.com:443"})

Getting the SHA-256 fingerprint

Extract public key sha265 fingerprint from PEM-encoded certificate file

openssl x509 -pubkey -noout -in certificate.pem | openssl pkey -pubin -outform der | openssl dgst -sha256 -binary | openssl enc -base64

Extract public key sha265 fingerprint from keyfile

openssl rsa -in certificate.key -pubout | openssl pkey -pubin -outform der | openssl dgst -sha256 -binary | openssl enc -base64

Extract public key sha265 fingerprint from HTTP server

servername=example.com; echo Q | openssl s_client -connect $servername:443 -servername $servername | openssl x509 -pubkey -noout | openssl pkey -pubin -outform der | openssl dgst -sha256 -binary | openssl enc -base64