#!/usr/bin/perl -w
use strict;
use CGI qw(referer redirect);

# index.cgi

my $site = 'http://mysite.com/';
my $newpage = 'newpage.html';
my $home = 'index.html';
my $q = new CGI;
if ($q->referer =~ /thatdomain/){
print redirect($site . $newpage);
}
else { print redirect($site . $home); }