AhaBulbStuff Everyone Should Know
AhaBulb: Stuff Everyone Should Know · ahabulb.com/secplus-firewall-deny-by-default

What is it called when a firewall blocks all traffic that has not been expressly permitted?

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  1. Allow by default
  2. Promiscuous forwarding
  3. Deny by default

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References

  1. NIST SP 800-41 Rev. 1, Guidelines on Firewalls and Firewall Policy nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-41r1.pdf Checked 2026-10-10.
  2. NIST SP 800-41 Rev. 1, Guidelines on Firewalls and Firewall Policy nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-41r1.pdf Checked 2026-10-10.

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