Actually - there is no need to use a cross-over cable and no danger of damage if you cross-connect the ethernet receive & transmit pairs - which is why I didn't bother to mention it.
10/100 mbit ethernet uses two pairs of wire, one for transmit and the other for receive and in most, but not all, cases, it is necessery to use a cross-over cable when connecting "like" devices - a host to another host or a switch to another switch - it is becoming increasingly common on switches to support "auto-MDIX" where the equipment senses the connection and configures it self appropriately.
1000 mbit (gigabit) ethernet uses all four pairs and supports auto-MDIX and so the DNS-323, with it's gigabit port, does not require a cross-over cable, but does require, if you are using gigabit, all four pairs to be wired.