Netopia 430 S/T, Reference Manual

Page: 143 / 276

7-10 Netopia ISDN Router Reference Guide
Each inspector has a specific task. One inspector’s task may be to
examine the destination address of all outgoing packages. That
inspector looks for a cer tain destination—which could be as specific
as a street address or as broad as an entire countr y—and checks
each package’s destination address to see if it matches that
destination.
A filter inspects data packets like a customs inspector scrutinizing packages.
Filter priority
Continuing the customs inspectors analogy, imagine the inspectors
lined up to examine a package. If the package matches the first
inspector’s criteria, the package is either rejected or passed on to
its destination, depending on the first inspector’s par ticular orders.
In this case, the package is never seen by the remaining inspectors.
If the package does not match the first inspector’s criteria, it goes
to the second inspector, and so on. You can see that the order of
the inspectors in the line is ver y impor tant.
INSPECTOR
FROM:
TO:
FROM:
TO:
FROM:
TO:
APPROVED