According to one example embodiment, a modem or other network device include an energy module configured to enter a low-power, low-bandwidth state when not in active use by a user. The low-power state may be maintained under certain conditions where network activity is not present, and or when only non-bandwidth-critical traffic is present. The network device may include a user interface for configuring firewall rules, and the user may be able to concurrently designate particular types of traffic as important or unimportant. The energy module may also be integrated with a firewall, and power saving rules may be inferred from firewall rules.