Improve TLS Config to prefer server ciphers, remove 3DES ciphers and require TLS 1.1 or higher

main.go

@@ -192,6 +192,30 @@ func main() {
 			}
 
 			server.TLSConfig = &tls.Config {
+				PreferServerCipherSuites: true,
+				MinVersion:               tls.VersionTLS11,
+
+				// Ciphersuites as defined in stock Go but without 3DES
+				// https://golang.org/src/crypto/tls/cipher_suites.go
+				CipherSuites: []uint16 {
+					tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
+					tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
+					tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+					tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+					tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
+					tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+					tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256,
+					tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
+					tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,
+					tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
+					tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
+					tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
+					tls.TLS_RSA_WITH_AES_128_GCM_SHA256, // does not provide PFS
+					tls.TLS_RSA_WITH_AES_256_GCM_SHA384, // does not provide PFS
+					tls.TLS_RSA_WITH_AES_128_CBC_SHA256,
+					tls.TLS_RSA_WITH_AES_128_CBC_SHA,
+					tls.TLS_RSA_WITH_AES_256_CBC_SHA,
+				},
 				Certificates: [] tls.Certificate{cert},
 			}
 			server.ForceTLS = *localForceTLS
@@ -215,6 +239,30 @@ func main() {
 			}
 
 			server.TLSConfig = &tls.Config {
+				PreferServerCipherSuites: true,
+				MinVersion:               tls.VersionTLS11,
+
+				// Ciphersuites as defined in stock Go but without 3DES
+				// https://golang.org/src/crypto/tls/cipher_suites.go
+				CipherSuites: []uint16 {
+					tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
+					tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
+					tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+					tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+					tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
+					tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+					tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256,
+					tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
+					tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,
+					tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
+					tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
+					tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
+					tls.TLS_RSA_WITH_AES_128_GCM_SHA256, // does not provide PFS
+					tls.TLS_RSA_WITH_AES_256_GCM_SHA384, // does not provide PFS
+					tls.TLS_RSA_WITH_AES_128_CBC_SHA256,
+					tls.TLS_RSA_WITH_AES_128_CBC_SHA,
+					tls.TLS_RSA_WITH_AES_256_CBC_SHA,
+				},
 				Certificates: [] tls.Certificate{cert},
 			}