So I came across a problem with a Java App not being able to open a connection to an Oracle Database. It wasn’t a problem with Credentials or the SID but a failure to connect. After a bit of digging I found that there wasn’t enough entropy in the system to get the required amount of bytes from /dev/random – the solution is to edit java.security to use /dev/urandom instead:
securerandom.source=file:/dev/urandom
Albal's Blog 