# rdns.regexp

WARNING: The services offered by this plugin, and much more, are now provided
more efficiently with the connect.rdns_access plugin. Please transition over
to using the new connect.rdns_access plugin, as this plugin is now deprecated
and may be removed in a future version of Haraka.

This plugin checks the reverse-DNS against a list of regular expressions. Any
matches will result in a rejection, unless there is an allow rule to
balance off broad regexes.

To give an example. Assume we add a rule to deny all hosts with dynamic
in the rDNS hostname (._dynamic._). Now we find a mail server,
generaldynamics.com that is clearly a false positive. We could try
to correct the original regex (clearly it is a poorly written regex), or
we could add an allow rule for generaldynamics.com (.\*generaldynamics\.com$).
This means that even though the dynamic block rule matches, it will be
superseded by the allow rule for generaldynamics.com.

## Configuration

- rdns.deny_regexps

  The list of regular expressions to deny. Over broad regexes in this list
  can be corrected by using the allow list.

- rdns.allow_regexps

  The list of regular expressions to allow. This list is always processed
  in favor of rules in the deny file.