Appendix D. Glossary
This glossary defines terms and acronyms used in the book. Multiword terms are alphabetized on the major noun in the term, followed by a comma and the rest of the term.
- ACCEPT
A firewall-filtering rule decision to pass a packet through to its next destination.
- accept-everything-by-default policy
A policy that accepts all packets that don't match a firewall rule in the chain. Therefore, most firewall rules are DENY rules defining the exceptions to the default accept policy.
- ACK
The TCP flag that acknowledges receipt of a previously received TCP segment.
- application-level gateway
Often referred to as ALG, an application-level (or layer) gateway is an overloaded term. In firewall terms, ALG often refers to application-specific support ...
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