[FLINK-9643] Flink allowing TLS 1.1 in spite of configuring TLS 1.2

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.3.2
• Fix Version/s: 1.4.2
• Component/s: Runtime / Coordination
• Assignee: Viktor Vlasov
• Reporter: Vinay
• Created: 22/Jun/18 08:15
• Updated: 02/Oct/19 17:43
• Resolved: 25/Jul/18 20:09

Description

I have deployed Flink 1.3.2 and enabled SSL settings. From the ssl debug 
logs it shows that Flink is using TLSv1.2. However based on the security 
scans we have observed that it also allows TLSv1.0 and TLSv1.1. 
  
In order to strictly use TLSv1.2 we have updated the following property of 
java.security file: 
jdk.tls.disabledAlgorithms=MD5, SSLv3, DSA, RSA keySize < 2048, TLSv1, 
TLSv1.1 

But still it allows TLSv1.1 , verified this by hitting the following command 
from master node: 

openssl s_client -connect taskmanager1:<listening_address_port> -tls1 

(here listening_address_port is part of 
akka.ssl.tcp://flink@taskmanager1:port/user/taskmanager) 

Now, when I hit the above command for the data port, it does not allow 
TLSv1.1 and only allows TLSv1.2