VariableIP_FILTER_RDNS
Introduced Version1.37
Description IP filter for filtering which IP addresses may be queried with the rdns() function.
Default

IP filter for filtering which IP addresses may be queried with the rdns() function.

The syntax of the IP address list is a sequence, separated by newlines or ;, of allow or deny actions, along with a CIDR block or all. An IP address is allowed or denied by finding the first match and applying the corresponding action. The all value matches any IP-address (i.e., IPv4 or IPv6).

For example, here we deny RDNS queries on the CIDR block 192.168.0.0/16 and allow all others:

ini
IP_FILTER_RDNS=deny 192.168.0.0/16; allow all