if !globalIAMSys.STSTLSConfig.InsecureSkipVerify { // Verify whether the client certificate has been issued by a trusted CA.
		_, err := certificate.Verify(x509.VerifyOptions{
			KeyUsages: []x509.ExtKeyUsage{
				x509.ExtKeyUsageClientAuth,
			},
			Intermediates: intermediates,
			Roots:         globalRootCAs,
		})
		if err != nil {
			writeSTSErrorResponse(ctx, w, ErrSTSInvalidClientCertificate, err)

			Organization: []string{"Acme Co"},
		},
		NotBefore: notBefore,
		NotAfter:  notAfter,

		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		BasicConstraintsValid: true,
	}

	hosts := strings.SplitSeq(host, ",")
	for h := range hosts {
		if ip := net.ParseIP(h); ip != nil {