Client TLS authentication

• Client TLS authentication filter architecture overview

• v3 API reference

• This filter should be configured with the name envoy.filters.network.client_ssl_auth.

Statistics

Every configured client TLS authentication filter has statistics rooted at auth.clientssl.<stat_prefix>. with the following statistics:

Name	Type	Description
update_success	Counter	Total principal update successes
update_failure	Counter	Total principal update failures
auth_no_ssl	Counter	Total connections ignored due to no TLS
auth_ip_allowlist	Counter	Total connections allowed due to the IP allowlist
auth_digest_match	Counter	Total connections allowed due to certificate match
auth_digest_no_match	Counter	Total connections denied due to no certificate match
total_principals	Gauge	Total loaded principals

REST API

GET /v1/certs/list/approved

The authentication filter will call this API every refresh interval to fetch the current list of approved certificates/principals. The expected JSON response looks like:

{
  "certificates": []
}

certificates

(required, array) list of approved certificates/principals.

Each certificate object is defined as:

{
  "fingerprint_sha256": "...",
}

fingerprint_sha256

(required, string) The SHA256 hash of the approved client certificate. Envoy will match this hash to the presented client certificate to determine whether there is a digest match.