RAD Data comm Modular Access Device with Integrated Router Blocking, Forwarding, Multiple Filters

FCD-IPMInstallation and Operation Manual Chapter 5 Setup Menu

Link

LAN to Link Filter

Traffic is Regulated

FCD-IPM

Traffic is Regulated

Link to LAN Filter

Figure 5-87. Action of an Advanced Filter

There are two modes through which filtering can be implemented: blocking and forwarding.

Blocking

The block command causes FCD-IPM to test every packet of data that is sent to or from the LAN. If the packet passes the test, passage is denied.

Example:

You want to ensure that IP/UDP packets do not go on to the link in the direction of the Internet/Intranet. Thus, you design a filter, which tests each packet to see if it is an IP/UDP packet. If the packet tests positive, it is automatically blocked.

Forwarding

The forward command works in the same way as the block command. However, with forwarding, if the packet passes the test, the packet is allowed to pass to or from the LAN.

Example:

To allow a certain user on the Small Office LAN to access the Internet for FTP purposes, create a filter to test each packet for the IP host address of the specified user and the FTP socket of the packet. If the packet passes the test, the packet is forwarded to the Internet/Intranet.

Multiple Filters

Up to 18 filters can be defined. If there are 2 filters that have contradictory operations, forwarding takes precedence over blocking.

Example:

You want to allow only one particular user on the Small Office LAN to access the Internet for FTP purposes. To insure that no one else is able to access the Internet, create a blocking filter for all traffic going to the link. To do this, from the Blocking and Forwarding menu enter Block all traffic for Link1. In addition, create a filter to test each packet for the IP host address of the specified user and the FTP socket of the packet. Since forwarding takes precedence over blocking, that user's frames are forwarded.

WAN Economy Menu 5-83