Referrer is not

Matches when the Referer request header does not match any wildcard patterns.

This condition inspects the Referer request header to determine if it does not match a specified list of wildcard patterns. It returns true if the header value matches none of the defined patterns.

Configuration

  • Case sensitive: Whether to enable case sensitivity during the comparison. When disabled, the condition performs a case-insensitive match against the Referer header sent in the request.
  • Referrer pattern: The input field used to add new wildcard patterns for exclusion. Multiple entries can be added simultaneously by separating them with a comma, a pipe (|), or a new line.
  • Defined patterns: The list of all active patterns for this condition. The condition returns true only if the requester’s referrer matches none of the entries in this list.

Pattern matching

The system supports flexible wildcard entries to simplify configuration. To ensure comprehensive matching, the system automatically translates wildcard entries into optimized regular expressions during processing:

  • Automatic conversion: Hostname-only patterns (e.g. *example*) are automatically converted to *://*example* to match any protocol.
  • Explicit patterns: You may provide full URLs or specific paths using wildcards (e.g. https://example.com/path/*).

Measurement

The condition extracts the Referer header from the incoming request and evaluates it against the Defined patterns.

  • Match found: If the header value matches any pattern in the list, the condition returns false.
  • No match found: If the header value matches none of the patterns, the condition returns true.
  • Missing header: If the Referer header is absent from the request, the condition returns true.

Performance

  • Sequential validation: To return true, the system must evaluate the entire list of patterns to ensure no matches exist. Large lists add an incremental processing cost to every request that passes through the filter.
  • Short-circuit optimization: The system stops processing and returns false as soon as it identifies a match. To optimize performance for traffic that should be excluded, place the patterns most likely to match at the top of the list.

Last modified March 5, 2026