ProxySG Content Policy Language Guide
restrict rdns
This definition restricts reverse DNS lookups and is useful in installations where access to reverse DNS resolution is limited or problematic. The definition has no name. It is global to policy evaluation and is not directly referenced by any rules.
If the requested URL specifies the host in IP form, no reverse DNS lookup is performed to match any category=, url=, url.domain=, or url.host= condition.
The special token all matches all subnets, and therefore can be used to restrict all
If a lookup is required to evaluate the trigger, the trigger evaluates to false.
A restrict rdns definition may appear multiple times in policy. The compiler attempts to coalesce these definitions, and may emit various errors or warnings while coalescing if the definition is contradictory or redundant.
Syntax
restrict rdns restricted_subnet_list
except exempted_subnet_list
end
where
•
•
Layer and Transaction Notes
Applies to all layers and transactions.
Example
The following definition restricts reverse DNS resolution for all but the 10.10.100.0/24 subnet:
restrict rdns all
except 10.10.100.0/24
end
See Also
•Conditions: category=, url=, server_url=
•Definitions: restrict dns
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