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Global Accelerated Learning • Est. 1999
Glossary Term Implicit Deny

Training Camp • Cybersecurity Glossary

What is Implicit Deny?

Implicit deny is the default-deny rule that blocks any traffic or action not explicitly permitted, enforcing least privilege in firewalls and ACLs.

Glossary > Network Security > Implicit Deny

Understanding Implicit Deny

Implicit deny is the default security principle that any action or traffic not explicitly permitted by a rule is automatically blocked. In firewalls and access control lists, an implicit deny sits at the end of the rule set so packets matching no preceding allow rule are dropped. This default-deny posture embodies least privilege and fail-safe design, ensuring that gaps in policy result in blocked rather than permitted access.

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