In all cases, we spoof the original source IP.

### Inbound Passthrough

Traffic entering a pod that is not transmitted over HBONE  (i.e. with a destination port != 15008) is handled by the "inbound passthrough" code path, on ztunnel's port 15006.

This is fairly straightforward.

First, we need to check that this traffic is allowed.

    env:
    - name: ISTIO_META_GENERATOR
      value: grpc
    - name: OUTPUT_CERTS
      value: /var/lib/istio/data
    {{- if eq (env .InboundTrafficPolicyMode "localhost") "passthrough" }}
    - name: REWRITE_PROBE_LEGACY_LOCALHOST_DESTINATION
      value: "true"
    {{- end }}
    - name: PILOT_CERT_PROVIDER
      value: {{ .Values.global.pilotCertProvider }}
    - name: CA_ADDR

          - POST
          - drain
  {{- end }}
    env:
    {{- if eq (env .InboundTrafficPolicyMode "localhost") "passthrough" }}
    - name: REWRITE_PROBE_LEGACY_LOCALHOST_DESTINATION
      value: "true"
    {{- end }}
    - name: PILOT_CERT_PROVIDER
      value: {{ .Values.global.pilotCertProvider }}
    - name: CA_ADDR

          - POST
          - drain
  {{- end }}
    env:
    {{- if eq (env .InboundTrafficPolicyMode "localhost") "passthrough" }}
    - name: REWRITE_PROBE_LEGACY_LOCALHOST_DESTINATION
      value: "true"
    {{- end }}
    - name: PILOT_CERT_PROVIDER
      value: {{ .Values.global.pilotCertProvider }}
    - name: CA_ADDR

  EXPECT_FALSE(cache.ValidateAndUpdateFileSignature(filename, 321));
  TF_EXPECT_OK(ReadCache(&cache, filename, 0, 16, &out));
  EXPECT_EQ(calls, 2);
}

TEST(RamFileBlockCacheTest, PassThrough) {
  const string want_filename = "foo/bar";
  const size_t want_offset = 42;
  const size_t want_n = 1024;
  int calls = 0;
  auto fetcher = [&calls, want_filename, want_offset, want_n](

	runTestGroup(t, testGroup{
		{
			desc:       "ztunnel",
			diffSelect: "DaemonSet:*:ztunnel",
		},
	})
}

// TestManifestGenerateHelmValues tests whether enabling components through the values passthrough interface works as
// expected i.e. without requiring enablement also in IstioOperator API.
func TestManifestGenerateHelmValues(t *testing.T) {
	runTestGroup(t, testGroup{
		{
			desc:       "helm_values_enablement",