check_rdns is a plugin for the system monitoring software
Nagios, which allows to check reverse DNS entries
using the tool dig.
The current version is available on
The plugin can be invoked with -h to get a list of options.
In my case, I actually use Icinga instead of Nagios.
Anyway, I added the following lines to ‘/etc/nagios-plugins/config/dns.cfg’ to
make check_rdns available for service definitions:
In the above code, the backslash indicates that the line should be continued
without a line break.