| Unspecified filter defaults:
Red ->| Port will filter all packets except for those protocols that you
explicitly allow. You explicitly allow a protocol by adding a
filter entry for the protocol, and set the port's arrow in the
entry to green. .
Green -> Port will forward (if appropriate) all packets except those
protocols which you explicitly disallow. To explicitly disallow
a protocol, add a filter entry for the protocol and set the port's
arrow in the filter entry to red.
In more words:
Example 1:
If you set the Unspecified Filter Defaults arrow for port 4 to be red (->|),
no packets will be forwarded. Now, go in and add a filter entry for the
protocol you like the most. Set the port 4 arrow in that filter entry to
green. Now, only your favorite protocol will be forwarded at port 4. Add
your least favorite protocol in a filter entry, and set its port 4 arrow to
green. Now, your favorite and least favorite protocols (and only those) can
be forwarded at port 4.
Example 2:
If you set the Unspecified Filter Defaults arrow for port 5 to be green (->),
all packets will be forwarded (as appropriate). Now add a filter entry for
your mother's favorite protocol, and set its port 5 arrow to red. Now, all
protocols EXCEPT your mother's favorite protocol will be forwarded (as
appropriate) at port 5.
[the "as appropriate" means that the basic bridging forwarding engine, based
on dest address, has final say on whether a packet is forwarded at a port.]
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