Pass Through Filters control access to and from addresses that have been specified as IP Pass Through. These filters are different from Remote Access and Outbound Filters in that they control both inbound and outbound access. Since Pass Through addresses are not translated, the GTA Firewall functions as a router or gateway for these addresses.
Pass Through Filters utilize IP Pass Through addresses in the definitions, not firewall network interface addresses.
Pass Through Filters are used in three cases:
When Pass Through hosts/networks are defined.
When setting up VPNs.
When the firewall is using bridging mode.
Typically, two filters are required for each hosts/networks IP address, one for outbound and the other for inbound access. If Pass Through hosts/networks are defined, auto-configuring filters will create a set based on the addresses defined on the Hosts/Networks screen. The auto-configured (default) filters will vary according to options selected.
The implicit rule, ìthat which is not explicitly allowed is denied,î applies to Pass Through filters. The rule is explicitly listed in the Pass Through Filters in version 3.5 and higher.
Pass Through filters are defined in the same manner as Remote Access or Outbound filters, and the rules concerning filter order also apply. See Managing Filters in Chapter 8 ñ Filters for filter set information, tips and fields for filters.
A Pass Through address must have two filters, inbound and outbound. Create the outbound connection filter by adding an empty filter definition, or editing an existing filter. Complete the filter definition in the same manner as an Outbound filter, specifying the same source IP address as that of the IP Pass Through address. Click OK.
Create the inbound connection filter by adding an empty filter definition, or editing an existing filter. Define the filter as you would a Remote Access Filter except that the destination IP address will be the Pass Through address, not the IP address on the GTA Firewall network interface. Click OK.
Once you have completed all the desired Pass Through Filters, click the SAVE button on the filter set to save the filters and apply them to the system.