| Variable | IP_FILTER_RDNS_SERVER | |
| Introduced Version | 1.37 | |
| Description | IP filter for filtering which DNS servers may be specified in the rdns() function. | |
| Default | | |
IP filter for filtering which DNS servers may be specified in the
rdns() function.
The syntax of these 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).
Note
This only restricts what value may be specified - if no server is specified then the system default or the one specified by RDNS_DEFAULT_SERVER will be used irrespective of whether it is blocked by this filter.
For example, here we restrict the server to
8.8.8.8 and
1.1.1.1 and deny all others.
IP_FILTER_RDNS_SERVER=allow 8.8.8.8; allow 1.1.1.1; deny all