bridge
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... link layer bridges (e.g., Ethernet bridges) that are
transparent to the IP layer although they will actually be inspecting
...
... the IP packets as they pass through (firewall/bridges).
Many of the messages used for establishment and maintenance of
...
...
For firewall/bridges, slightly different considerations apply. The
physical links on either side of the firewall ...
... physical links on either side of the firewall/bridge are treated as a
single logical link for the purposes of IP ...
... messages used for discovery functions on the link must be allowed to
transit the transparent bridge. Administrators should ensures that
routers ...
... hosts attached to the link containing the firewall/bridge
are built to the correct specifications so that out-of-specification
packets are actually dropped as described in the earlier part of this
...
... firewall can generally be thought of as a special case of
a firewall/bridge, but the only link-local messages that need to be
allowed through are those directed to the host ...
... local addresses should be filtered.
# Do not use this if the firewall is a bridge.
# Optional for firewalls that are routers ...