I've installed Oracle 12c smoothly today and was able to start
lsnrctl and database.
SQL*Plus connection is okay inside VM.
I've set the IP address to be static @ 192.168.0.20 (CentOS VM).
I am able to ping the VM address from Windows but I cannot connect to the database through SQL Developer inside Windows. This is the error I got:
The network adapter is unable to establish the connection
I suspect it may be a firewall problem? But I have opened port 1521 using