User manual

• NAT Mode

This mode enables Dynamic Network Address Translation (NAT) use between the LAN and

WAN interfaces. This means that the individual IP addresses of hosts on the LAN interface will

be hidden from the public internet. All traffic coming from the public Internet to LAN hosts will

be directed to the public IP address of the WAN interface and NetDefendOS will perform the

necessary IP address translation.

Enabling NAT is a recommended way to shield the users and hosts on the LAN network from

outside attack. It also means that a DFL-160 requires just a single public IP address to be

allocated by the ISP.

• Router Mode

This is the mode used if NAT is not used. It means that each the individual hosts and users on

the LAN network need their own public IP addresses if they are to communicate with the public

Internet.

Although not recommended when WAN is connected to the public internet, there may be

situations where NAT cannot be applied and the individual LAN network addresses need to be

exposed through the WAN interface.

In some scenarios, the WAN interface may be connected to another internal network and in this

case NAT usage may also not be appropriate because there is no need to shield LAN addresses

and there are lots of internal IP addresses that can be used.

• Transparent Mode

This mode is used if the DFL-160 is to be placed between the LAN and WAN interface in a

transparent way. This means that no IP addresses need to be changed in either network, but the

traffic flowing between the interfaces is still subject to the rules and controls imposed by

NetDefendOS.

In transparent mode, NetDefendOS works out from the traffic itself which networks can be

found on the interfaces and creates the necessary entries in its routing table.

Note

In transparent mode, the LAN interface takes on the same IP address as the WAN

interface.

If both the LAN and DMZ interfaces have transparent mode enabled, traffic will flow

transparently between all 3 of the DFL-160 interfaces.

C. DHCP Server Settings

With this option enabled, a range of IP addresses can be allocated which can then be allocated out to

hosts on the network that need them. The presentation of the DHCP server options in the web

interface is shown below.

In most scenarios, the LAN network will be an "internal" network that does not require public IP

addresses. However, if a range of public IP addresses are allocated by the ISP these could also be

allocated using this feature.

NetDefendOS also allows a DHCP Reservations list to be created. These bind a certain IP address

3.3. LAN Settings Chapter 3. The System Menu