title: how to set Diffie Hellman key size to 2048 in OpenJDK
body: <p>A security audit I just ran turned up that we are using a sub-par key strength (recommended 2048 or higher, ours is 1024 bits) for the Diffie-Hellman groups (TLS). Upon researching I found that starting JDK 8 we can set the DH key size to be 2048. 
  All the options suggested in <a href="https://stackoverflow.com/questions/24502672/how-to-expand-dh-key-size-to-2048-in-java-8">How to expand DH key size to 2048 in java 8</a>
  apply to Oracle JDK and they do work for that.</p>
  
  <p>However, when I try to set <code>-Djdk.tls.ephemeralDHKeySize=2048</code> as JVM argument on my Ubuntu with OpenJDK 8 it is still remaining to be 1024 bits. Any help is appreciated.</p>