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Blue dot Installation Guide

Copyright (C) 1999-2005, Matti Tukiainen. All rights reserved.

This file is part of Blue dot.

Blue dot is distributed with NO WARRANTY OF ANY KIND. No author or distributor accepts any responsibility for the consequences of using it, or for whether it serves any particular purpose or works at all, unless he or she says so in writing. Refer to the GNU General Public License (the "License") for full details.

Table of Contents


  1. A web site with the ability to run Perl CGI scripts.
  2. Zipped Blue dot distribution file bluedot-x.x.zip. New versions are occasionally available at: http://ktmatu.com/software/bluedot/.


  1. Unzip bluedot-x.x.zip to some directory.
  2. Change the first line of bluedot.pl (#!/...) to correspond the path where the perl interpreter is located.
  3. Configuration: Change the variable $LOG_DIR in bluedot.pl to point where you will place the log files on your server.
    $DEFAULT_TIME_ZONE, and $DEFAULT_DST_TIME_ZONE can also be edited if the time zone information is important.
    $ENABLE_REVERSE_DNS = 1 means that host names instead of IP addresses are logged (e.g. ml30pc3.uta.fi instead of Setting this variable to 0 is slightly faster because there is no need to do reverse DNS. Log files having host names instead of IP addresses also take more space.
    $ENABLE_COOKIE_LOG = 1 instructs Blue dot to store the values of PID (Persistent ID) and SID (Session ID) cookies to the end of each log entry. Blue dot sets a new session ID to every new session if this option is enabled. Session IDs can be used to detect unique visitors. Persistent ID should remain the same for a longer period and it can be used to count repeat visitors. Various things that you can do with the cookie log enabled Blue dot log files are given on a Dotlog Analysis Tools Example page. Setting this variable to 0 makes Blue dot generated logs smaller and more compatible. N.B. The accuracy of Cookie based tracking reduces substantially if the site you are running Blue dot (e.g. example.com) is not the same as the site you are tracking (e.g. example.net). This is caused by the fact that many modern browsers block third party cookies. Browser settings and separate cookie blocking software also negatively affects the accuracy of cookie logging even if Blue dot and the tracked site are on the same domain. Cookie logging doesn't work if you are running Blue dot as a SSI script.
  4. Log in to the site, create a directory (mkdir ...) you specified above and chmod its permissions (attributes) to something like 700 (chmod 700).
  5. Copy an empty accesslog file to the log directory. Chmod its permissions to 600.
  6. Copy the bluedot.pl file into the cgi-bin directory. Depending on how the server is configured chmod its permission to 705, 755 or something like that. Sometimes bluedot.pl must be renamed to bluedot.cgi .
  7. Test it! Modify this URL to reflect your site: http://www.example.com/cgi-bin/bluedot.pl?id=accesslog and give it to the browser. If everything goes well, there should be a tiny blue dot visible on the screen and the accesslog file contains information about the download.
  8. Add Blue dot code to web pages you want to log.

Add Blue dot code to web pages

There are several different ways to call Blue dot from your web pages. Each method needs a different kind of code snippet which must be added to your web pages. Blue dot Code Generator can be used to create these snippets. The table below summarizes the characteristics of different call methods:

Feature JavaScript + CGI JavaScript + CGI + SSI       SSI       Click Log
Each page requires a unique Blue dot code snippet yes no no yes (each link)
Supports cookie logging yes yes no yes
Tracks all activity (including robot like googlebot) no no yes no
Registers which links and buttons were clicked no no no yes

It is possible to have different kind of "blue dots" on one page, JavaScript + CGI links to track the usage of page and Click Log to measure what links and buttons are clicked on that page, for example.

Web pages containing SSI must usually have a+x permissions to work correctly. Check these issues from your server's documentation.


It is possible to have an unlimited number of log files. Just remember to first create an empty log file and copy it into log directory. Information is written into bluedotlog file if the specified log file doesn't exist.

Different kind of server errors can be logged if the Blue dot code snippet is placed into server's error pages. For this purpose it is advisable to create a separate log file file, like errorlog. On an Apache web server, for example, it is possible to track what kind of missing pages are requested if the blue dot is placed in to the page defined by the ErrorDocument entry in the .htaccess file. In the case of ErrorDocument 404 /error-404.html Blue dot should be placed into error-404.html file in the root directory.

It is possible to use a user specified image instead of the default blue dot. Just specify the URL of the image in Blue dot Code Generator.

Blue dot can also be used as a file download counter. First create a code snippet with the Code Generator, use a file to be downloaded as Image URL. Copy only the contents of src="..." within noscript tags, and use it as a download URL.

With the help of CSS it is possible to completely hide the blue dot. Enclose the generated JavaScript snippet inside the construct shown below:

<div style="display: none;">

Installation and Configuration Service

To make most out of Blue dot and minimize the hassle, it is possible to use the Installation and Configuration Service. This service guarantees that Blue dot is correctly installed and configured.

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