HADOOP-16000. Remove TLSv1 and SSLv2Hello from the default value of hadoop.ssl.enabled.protocols

Signed-off-by: Akira Ajisaka <aajisaka@apache.org>

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/ssl/SSLFactory.java

@@ -72,7 +72,7 @@ public class SSLFactory implements ConnectionConfigurator {
   public static final String SSL_ENABLED_PROTOCOLS_KEY =
       "hadoop.ssl.enabled.protocols";
   public static final String SSL_ENABLED_PROTOCOLS_DEFAULT =
-      "TLSv1,SSLv2Hello,TLSv1.1,TLSv1.2";
+      "TLSv1.1,TLSv1.2";
 
   public static final String SSL_SERVER_NEED_CLIENT_AUTH =
       "ssl.server.need.client.auth";

hadoop-common-project/hadoop-common/src/main/resources/core-default.xml

@@ -2417,9 +2417,10 @@
 
 <property>
   <name>hadoop.ssl.enabled.protocols</name>
-  <value>TLSv1,SSLv2Hello,TLSv1.1,TLSv1.2</value>
+  <value>TLSv1.1,TLSv1.2</value>
   <description>
-    The supported SSL protocols.
+    The supported SSL protocols. The parameter will only used from
+    DatanodeHttpServer.
   </description>
 </property>