Creating Filters Using the OfficeConnect Remote 840 Manager 12-5
The first is the direction/location of the packet. There are four static direction/locations on which filters can be activated: incoming LAN traffic, outgoing LAN traffic, incoming WAN traffic and outgoing WAN traffic. Additionally, there are two for each Remote Site, traffic coming from and going to each one.
The second criteria is whether the packet contains data that matches the condition(s) in the filter. Conditions are defined based on protocol specific information such as IP source address or IPX source socket number.
All filters are set up to discard packets (data filters). However, there are two ways of specifying these actions: a “negative” and a “positive” way. The negative action specifies that the packet or information is discarded if the filter criteria met. The positive action specifies that the packet or information is kept if the criteria is met. The positive way implies that all packets or information not meeting the criteria are discarded. Either method can be used for most filters. However, one or the other is almost always more logical.
For example, imagine a small office with 20 workstations on the LAN. The LAN is connected to a remote corporate office using an OfficeConnect Remote 840. Two of the LAN workstations are used by contractors who are not given access to the corporate office. To prevent traffic from the two workstations from passing through the OfficeConnect Remote 840, a filter is set up on the incoming/LAN direction/location. The most logical filter is a “negative” filter that says “discard packet if IP source address is equal to xxx.xxx.xxx.xxx or IP source address is equal to xxx.xxx.xxx.yyy”. Of course you could write a “positive” filter which would say “forward packet if IP source address is equal to <list of the 18 IP addresses that are allowed to send traffic>”. However, you can see that the negative filter is shorter (more efficient to apply) and easier to write and therefore the better one to use.
Each direction/location can have up to fifteen filters. Each filter can have up to six conditions. As you create the filter, you can select whether to logically “and” or “or” conditions together. If you need a filter with more than six conditions, you can create multiple filters that will be looked at by the OfficeConnect Remote 840 as if they were one filter. The only requirement is that the basic filter information (i.e., the protocol and the action) must be the same in each of the filters. The filters will be “or”ed together when they are merged internally.
