D-Link NetDefendOS User Manual page 182

In addition to the interface IP address, a Network address is also specified for an Ethernet
interface. The Network address provides information to NetDefendOS about what IP
addresses are directly reachable through the interface. In other words, those residing on the
same LAN segment as the interface itself. In the routing table associated with the interface,
NetDefendOS will automatically create a direct route to the specified network over the actual
interface.
• Default Gateway
A Default Gateway address can optionally be specified for an Ethernet interface. This is
normally the address of a router and very often the router which acts as the gateway to the
Internet.
When a default gateway is specified then, by default, a route to the network all-nets is
automatically created in the NetDefendOS routing table for the interface. This means that any
traffic which does not have a more specific matching route will be sent via that interface to
the default gateway. This behavior can be changed by disabling an interface's advanced
option for creating the default route automatically.
Normally, only one default all-nets route to the default gateway needs to exist in the routing
table.
Note: The all-nets IP address object
The all-nets IP object (IP address: 0.0.0.0/0) includes the multicast IP address range
(224.0.0.0 => 239.255.255.255). For more information about this topic, see
Section 4.7, "Multicast Routing".
• Receive Multicast Traffic
This option controls the reception of multicast IP packets on that interface. There are three
options:
i. Off - Promiscuous mode is switched off so that multicast packets are silently dropped.
Promiscuous mode will still be automatically switched on with OSPF or high availability.
ii. On - Multicast traffic can always be received by the interface. Promiscuous mode is
always the receive mode of the interface.
iii. Auto - If an IP rule exists in the rule set which applies to a multicast packet's destination
IP address, then the Ethernet interface automatically gets its receive mode set to
promiscuous in order to receive multicast packets. This is the default.
This setting does not affect the automatic usage of promiscuous mode with OSPF or high
availability. For a further discussion of promiscuous mode, see the description below.
• Enable DHCP Client
NetDefendOS includes a DHCP client feature for dynamic assignment of address information
by a connected DHCP server. This feature is often used for receiving external IPv4 address
information from an ISP's DHCP server for public Internet connection.
The information that can be set using DHCP includes the IPv4 address as well as the
broadcast address of the interface, the local network that the interface is attached to, and the
default gateway.
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Chapter 3: Fundamentals