Very good, but there is a small bug

Works like a charm.

But there is one bug.
If the hostname can’t be resolved into an IP address, you get an error on line 141.
To fix this, i edited the function blkcheck to look like this:

sub blcheck
{
my ($ip, $bl) = @_;
my $lookupip = $ip;
if (!defined($lookupip)) {
print (“ERROR: hostname could not be resolved.n”);
exit $ERRORS{“UNKNOWN”};
}
$lookupip =~
s/([0-9]{1,3}).([0-9]{1,3}).([0-9]{1,3}).([0-9]{1,3})/$4.$3.$2.$1.$bl/;
if (lookup($lookupip)) { return 1 }
else { return 0 }
}