Operation Manual

Cerberus ADSL2 Wi-Fi Plus (P6331-6)

For example, if you set the port number 80 (Web/HTTP) to be mapped to the IP Address

192.168.1.2, then all incoming HTTP requests from outside users are forwarded to the local

server (PC) with the IP address of 192.168.1.2. If the port is not listed as a predefined

application, you need to add it manually.

In addition to specifying the port number used, you also need to specify the protocol used. The

protocol is determined by the particular application. Most applications use TCP or UDP,

however you can specify other protocols using the drop-down Protocol menu. Setting the

protocol to “all” causes all incoming connection attempts using all protocols on all port

numbers to be forwarded to the specified IP address.

DMZ – The DMZ Host is a local computer exposed to the Internet. When setting a particular

internal IP address as the DMZ Host, all incoming packets are checked by the Firewall and

NAT algorithms, then passed to the DMZ host when a packet received does not use a port

number in use by any other Virtual Server entries.

Note: Using port forwarding does have security implications, since outside users are

able to connect to PCs on your network. For this reason you are advised to use specific

Virtual Server entries just for the ports your application requires instead of simply

using DMZ or creating a Virtual Server entry for “All” protocols, as doing so results in

all connection attempts to your public IP address accessing the specified PC.

Attention: If you disable the NAT option in the WAN-ISP section, the Virtual Server

function becomes invalid.

Attention: If the DHCP server option is enabled, you have to be very careful in

assigning the IP addresses of the virtual servers in order to avoid conflicts. The easiest

way of configuring Virtual Servers is to manually assign a static IP address to each

virtual server PC, with an address that does not fall into the range of IP addresses that

are issued by the DHCP server. You can configure the virtual server IP address

manually, but it must still be in the same subnet as the router.