tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
	}
}

// TLSCiphersBackwardCompatible returns a list of supported
// TLS transport cipher suite IDs.
//
// In contrast to TLSCiphers, the list contains additional
// ciphers for backward compatibility. In particular, AES-CBC
// and non-ECDHE ciphers.
func TLSCiphersBackwardCompatible() []uint16 {
	return []uint16{
		tls.TLS_CHACHA20_POLY1305_SHA256, // TLS 1.3

			MinVersion:               tls.VersionTLS12,
			NextProtos:               []string{"http/1.1", "h2"},
			ClientSessionCache:       tls.NewLRUClientSessionCache(64),
			CipherSuites:             crypto.TLSCiphersBackwardCompatible(),
			CurvePreferences:         crypto.TLSCurveIDs(),
		}
		// This is only to support client side certificate authentication
		// https://coreos.com/etcd/docs/latest/op-guide/security.html

	s := xhttp.ConnSettings{
		LookupHost:       globalDNSCache.LookupHost,
		DialTimeout:      defaultDialTimeout,
		RootCAs:          globalRootCAs,
		CipherSuites:     crypto.TLSCiphersBackwardCompatible(),
		CurvePreferences: crypto.TLSCurveIDs(),
		TCPOptions:       globalTCPOptions,
		EnableHTTP2:      false,
	}

	if clientCert != "" && clientKey != "" {

			ServerName:         host,
			MinVersion:         tls.VersionTLS12,
			NextProtos:         []string{"h2", "http/1.1"},
			ClientSessionCache: tls.NewLRUClientSessionCache(100),
			CipherSuites:       crypto.TLSCiphersBackwardCompatible(), // Contains RSA key exchange
			RootCAs:            rootCAs,
		},
	}

	// Parse explicitly set enable=on/off flag.
	isEnableFlagExplicitlySet := false
	if v := getCfgVal(config.Enable); v != "" {