de>, that configures the sidecar handling
of external services, that is, those services that are not defined in Istio&rsquo;s internal service registry.
If this option is set to <code>ALLOW_ANY</code>, the Istio proxy lets calls to unknown services pass through.
If the option is set to <code>REGISTRY_ONLY</code>, then the Istio proxy blocks any host without an HTTP service or
service entry defined within the mesh.
<code>ALLOW_ANY</code> is the default value, allowing you to start evaluating Istio quickly,
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