Developing a Firewall Policy
The establishment of a firewall policy simplifies the practice of
deciding what traffic to permit and what to filter.
Moreover, a consistent, and consistently applied,
policy is a strong argument by system administrators to deny individual
requests for new small holes in the firewall by individuals.
Surprisingly the 'firewall community' is divided on default behaviours.
Either:
- 'that which is not expressly forbidden is permitted', or
- 'that which is not expressly permitted is forbidden'.
There exists a clear balance between security and user freedoms,
and for many organizations (e.g. freedom-loving universities)
there is often no simple answer.
However,
it is unwise (ignorant)
to consider that an attack on external hosts and
networks could not be launched from within your internal network.
For this reason, conventional wisdom says we should have mirrored denial
policies filtering traffic leaving our networks.
CITS3002 Computer Networks, Lecture 11, Security of TCP/IP, p19, 15th May 2024.
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CITS3002