This SQL exception is thrown
1. when the connection query string is wrong.
2. there is no physical connection ie the server is
not being able to connect to your DB m/c

Solutions:

1. Check your connection string
2. make sure that you at the minimal able to ping your
DB server

Run the ping command as follows:

ping <db m/c>

if you are using a name like "dbserver" instead of a
pure IP make sure that your
/etc/hosts files has a corresponding entry (Ask your
Network Admin he will help you out on this)

But the main trouble I feel is your connection string

By connection string I mean this line in your
class/configuration files

"jdbc:oracle:thin:@everest:1521:everora"

Also verify that you able to do a dbping through
SQLNet

or you are able to connect from your sqlplus from
linux.