# prometheus-dnssec-exporter

A Prometheus exporter that exposes metrics on DNSSEC-signed DNS zones.
One of its core features is that it compares a zone's `CDS` record set
to the `DS` record set in the parent zone.

## Installation

### From Source

```bash
git clone https://gitlab.com/s3lph/prometheus-dnssec-exporter
cd prometheus-dnssec-exporter
make prometheus-dnssec-exporter
```

### Debian Package

There is an automatically built Debian package in my repository [https://repo.s3lph.me/]:

```bash
wget -O /etc/apt/trusted.gpg.d/repo.s3lph.me.gpg https://repo.s3lph.me/debian/repo.s3lph.me.gpg
echo "deb https://repo.s3lph.me/debian stable main" > /etc/apt/sources.list.d/repo.s3lph.me.list
apt update
apt install prometheus-dnssec-exporter
```

If you do not want to add my repository to your system, you can also download the deb package from the repository: https://repo.s3lph.me/debian/pool/main/p/prometheus-dnssec-exporter/

Or you can build the package yourself: https://gitlab.com/s3lph/custom-packages/-/blob/main/prometheus-dnssec-exporter/build.sh

## Usage

### Configuration

The DNSSEC exporter requires a configuration file.  When using the Debian package, this file is located at `/etc/prometheus/dnssec-exporter/config.yaml`

```yaml
---

## dnssec exporter configuration
#
#dns:
#  # The resolver to use.  Must be DNSSEC validating, and
#  # must not strip DNSSEC responses.
#  resolver: 1.1.1.1:53
#  # List of zones to resolve.
#  zones:
#    - example.org.
#    - example.com.

## TLS and Basic Auth can be configured here as well, see for details:
## https://github.com/prometheus/exporter-toolkit/blob/master/web/tls_config.go#L36
#
#basic_auth_users:
#  user1: pass1
#  user2: pass2
#tls_server_config:
#  cert_file: server.crt
#  key_file: server.key
```

You should at least provide the resolver to use (the DNSSEC exporter only works with a DNSSEC-validating resolver!) and the zones you want to collect metrics on:

```yaml
---
dns:
  resolver: 9.9.9.9:53
  zones:
    - example.org.
	- example.com.
```

### Running

You can start the exporter using the following command:

```bash
prometheus-dnssec-exporter --config=path/to/dnssec-exporter/config.yaml --web.listen-address=:9142
```

The Debian package provides a systemd service unit that does the job for you:

```bash
systemctl enable --now prometheus-dnssec-exporter
```

## Metrics

The following metrics are exposed at the `/metrics` HTTP endpoint:

```prom
# HELP dnssec_cds_count Number of CDS records present in the zone
# TYPE dnssec_cds_count gauge
dnssec_cds_count{parent="ch.",tld="ch.",zone="example.org."} 1
dnssec_cds_count{parent="me.",tld="me.",zone="example.com."} 1
dnssec_cds_count{parent="example.com.",tld="me.",zone="subdomain.example.com."} 1
# HELP dnssec_cds_ds_match 1 if the CDS and DS records match, 0 otherwise
# TYPE dnssec_cds_ds_match gauge
dnssec_cds_ds_match{parent="ch.",tld="ch.",zone="example.org."} 0
dnssec_cds_ds_match{parent="me.",tld="me.",zone="example.com."} 1
dnssec_cds_ds_match{parent="example.com.",tld="me.",zone="subdomain.example.com."} 1
# HELP dnssec_cds_rcode RCode of the CDS record answer
# TYPE dnssec_cds_rcode gauge
dnssec_cds_rcode{parent="ch.",tld="ch.",zone="example.org."} 0
dnssec_cds_rcode{parent="me.",tld="me.",zone="example.com."} 0
dnssec_cds_rcode{parent="example.com.",tld="me.",zone="subdomain.example.com."} 0
# HELP dnssec_ds_count Number of DS record is present in the parent zone
# TYPE dnssec_ds_count gauge
dnssec_ds_count{parent="ch.",tld="ch.",zone="example.org."} 1
dnssec_ds_count{parent="me.",tld="me.",zone="example.com."} 1
dnssec_ds_count{parent="example.com.",tld="me.",zone="subdomain.example.com."} 1
# HELP dnssec_ds_rcode RCode of the DS record answer
# TYPE dnssec_ds_rcode gauge
dnssec_ds_rcode{parent="ch.",tld="ch.",zone="example.org."} 0
dnssec_ds_rcode{parent="me.",tld="me.",zone="example.com."} 0
dnssec_ds_rcode{parent="example.com.",tld="me.",zone="subdomain.example.com."} 0
# HELP dnssec_signature_ok 1 if the DNSSEC signature is present and valid, 0 otherwise
# TYPE dnssec_signature_ok gauge
dnssec_signature_ok{parent="ch.",tld="ch.",zone="example.org."} 1
dnssec_signature_ok{parent="me.",tld="me.",zone="example.com."} 1
dnssec_signature_ok{parent="example.com.",tld="me.",zone="subdomain.example.com."} 1
# HELP dnssec_signature_rcode RCode of the DNS query
# TYPE dnssec_signature_rcode gauge
dnssec_signature_rcode{parent="ch.",tld="ch.",zone="example.org."} 0
dnssec_signature_rcode{parent="me.",tld="me.",zone="example.com."} 0
dnssec_signature_rcode{parent="example.com.",tld="me.",zone="subdomain.example.com."} 0
```

The two metrics that are probably the most important are:

- `dnssec_signature_ok`: If this is 0, the chain of trust to your zone is broken.
- `dnssec_cds_ds_match`: If this is 0, it's most likely a KSK rollover is in progress.  If your registry does not support CDS submission, this is the sign that you need to replace the `DS` records in the parent zone.