# firewall rule

CEFR B2 · Compound

Source: https://englishreference.com/word/firewall-rule
Updated: 2026-07-22

## Definition

a specific instruction that tells a computer network which traffic to allow and which to block. It acts like a security guard for your internet connection.

For teachers: a specific configuration setting within a network security system that determines whether to permit or deny traffic based on criteria like IP address or port number.

## Examples

- The administrator added a firewall rule to block the suspicious website.
- After the security breach, the IT team updated every firewall rule to ensure only authorized employees could access the server.
- Effective network security relies on a strictly ordered set of firewall rules, where more specific permissions are evaluated before a general 'deny all' instruction at the end of the list.

## Usage notes

- Often used in the plural when discussing security policies; typically takes verbs like 'configure', 'implement', or 'bypass'.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.