'Add a rule to the SecurityGroup object.  Note that this method
only changes the local version of the object.  No information
is sent to EC2.'

def add_rule(self, ip_protocol, from_port, to_port, src_group_name, src_group_owner_id, cidr_ip, src_group_group_id, dry_run=False):

    rule = IPPermissions(self)
    rule.ip_protocol = ip_protocol
    rule.from_port = from_port
    rule.to_port = to_port
    self.rules.append(rule)
    rule.add_grant(src_group_name, src_group_owner_id, cidr_ip, src_group_group_id, dry_run=dry_run)
