def ec2_entities(job_name):
    """
    Returns the name of basic ec2_entities.
    * Keypair name
    * Security group for slaves
    * Security group for master

    @param job_name: User given name of the Job.
    @type job_name: string
    """

    keypair_name = "multistack-" + job_name
    sec_slave = "multistack-" + job_name + "-slave"
    sec_master = "multistack-" + job_name + "-master"
    return keypair_name, sec_master, sec_slave