Run this script to have a look at your environment:

#!/usr/bin/perl -wT
use strict;
print "Content-type: text/html\n\n";
print "<p><b>$_</b><br>$ENV{$_}\n" for sort keys %ENV;
[download]

What I expect you will find is the REMOTE_ADDR contains a value but REMOTE_HOST does not. This occurs because reverse DNS lookups need to be enabled on the server to allow your server to convert REMOTE_ADDR into a hostname.

You should be able to convert REMOTE_ADDR into a hostname yourself using gethostbyaddr():

use Socket;
$iaddr  = gethostbyname('www.perlmonks.com');
$name   = gethostbyaddr($iaddr, AF_INET);
print $name;
[download]

cheers

tachyon

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