can some one help me on this

i have an oracle database which is accessed by a java application from a remote machine. From the java application iam giving the ip address of the server machine where oracle is running.the server also receives the ip address of the machine from where the call is made.

now my question is, can i restrict from oracle that only, request from a specific ip address should be allowed to access the database and the rest should not. if so how.

thanks in advance