user manual

Wireless Cable Modem Gateway CGD24G User Manual
Content Filtering and Firewall Rules 3-7
v1.1, May 2009
• Protocol. Select the protocol for the ports:
– TCP. Select TCP only.
– UDP. Select UDP only.
– Both. Select both TCP and UDP.
• Local IP Address. Complete the local IP address for the computer that is using the
service.
4. Perform one of the following actions:
• Click Add to save your settings. The Active Forwarding Rules table now displays the list
of ports that are currently forwarded.
• To delete a service, select the radio button in the Active Forwarding Rules table for the
service that you want to delete, and then click Delete.
Considerations for Port Forwarding
• If the IP address of the local server PC is assigned by DHCP, it may change when the PC is
rebooted. To avoid this, you can assign a static IP address to your server outside the range that
is assigned by DHCP, but in the same subnet as the rest of your LAN. By default, the IP
addresses in the range of 192.168.0.2 through 192.168.0.9 are reserved for this purpose.
• Local PCs must access the local server using the PCs’ local LAN address (192.168.0.XXX, by
default). Attempts by local PCs to access the server using the external WAN IP address will
fail.
Remember that allowing inbound services opens holes in your firewall. Only enable those ports
that are necessary for your network.
Configuring Port Blocking
You can use port blocking to block outbound traffic on specific ports.
Note: To reset the selection in the Service field and to clear all the fields in the Add
Custom Rules table, click Reset.
Note: Any outbound traffic that is not blocked by rules that you have created is allowed
by the default rule.