Frequently Asked Questions (FAQ)
about
WWW-page Access Counter

Version 1.2
Release date: September 1, 1995
Author: Heini Withagen, heiniw@dhp.nl

Installation
  1. Where can I find the most recent version of the FAQ and the software ?
  2. Compilation under which operating systems is possible ?
  3. Which WWW-server software is required ?
  4. Successful compilation but no image in my pages. What's wrong ?
  5. What should I specify as CGIBIN_DIR in the Makefile ?
  6. Why does the resulting binary start with the 'nph-' ?
  7. Can I edit the 'count_file' with a normal text editor ?
  8. Do I need to do anything special when upgrading to the current version ?

Usage
  1. Which arguments are accepted by the program ?
  2. What to add in a HTML-page ?
  3. How to keep track of a page without anybody knowing ?
  4. How to reset a certain counter to zero ?
  5. Can people from the rest of the Internet (ab)use the counter ?
  6. What's the size of the resulting output image ?

Installation

  1. Where can I find the most recent version of the FAQ and the software ?
    Both the FAQ and counter software package can be found at http://www.eeb.ele.tue.nl/counter/index.html

  2. Compilation under which operating systems is possible ?
    Successful compilation under the following operating systems has been achieved:
    • Linux 1.1.58 with cc and gcc 2.5.8
    • SunOS 4.1.3 with gcc 2.6.3 (cc will not work)
    • Solaris 2.4 with gcc 2.5.6
    • IRIX 5.3 with cc and gcc 2.6.3
    • HP-UX A.09.01 with cc and gcc 2.6.0

  3. Which WWW-server software is required ?
    The counter software should work with any WWW-server package which supports CGI-scripts like NCSA httpd, CERN httpd, Netsite, and many more.

  4. Successful compilation but no image in my pages. What's wrong ?
    The two most common errors in this case:
    • The read/write permissions on the count_file are wrong.
      The location of the count_file is specified in conf.h. The file which is specified there should be writable by the userid under which the WWW-server is running. Most common is that the server is running under the userid of nobody.
    • The nph-count binary is installed in a directory where it's not possible to execute CGI-scripts. Check with the question on CGI-directories for more information.

    An on-line debugging tool is now incorporated with the counter software. If the counter binary is installed in a directory from which it is possible to execute CGI-scripts try the following by directly opening the URL:
    http://localhost/cgi-bin/nph-count?link=dummy&debug=ON
    The returned HTML-page should provide additional information about possible sources of errors.

    Error messages from the program are also logged to a location of your liking. Specify in the 'conf.h' where the messages should go.

  5. What should I specify as CGIBIN_DIR in the Makefile ?
    In most cases it is best to specify the global cgi-bin directory as the place to install the binary. This system administrator usually only has access to this place.
    However, if you are a user on a system and you would like to install the package in your local directory on the server, you have to make sure that it is possible to execute CGI-scripts in user-directories on your server (in most cases this is disabled; check with your system administrator). If it is possible to do that, most probably the binary has to have the extension .cgi. Just copy the resulting binary to nph-count.cgi.

  6. Why does the resulting binary start with the 'nph-' ?
    Some WWW-server packages have problems when a CGI-script produces a GIF-picture as an output. The server parses the output of the CGI-script to determine what the header of the return message should be. To prevent the server from doing this you have to start the name of the CGI-script with 'nph' which stands for no parse header.

  7. Can I edit the 'count_file' with a normal text editor ?
    You shouldn't edit the 'count_file' yourself. In most cases, it will become corrupt and all other counters in the file might be reset.

  8. Do I need to do anything special when upgrading to the current version ?
    If you already have a previous version of the counter software running be carefull during installation of the current version. You will have to make sure that during the installation the nph-count binary is not called. This can best be achieved by disabling the WWW-server for some time (try to minimize this as your server will not be accessible during that time).


Usage

  1. Which arguments are accepted by the program ?
    The following arguments are currently recognized:
    • width=number
      Specifies the number of digits in the resulting image.
    • link=URL of the page on which the counter is located
      The link-argument is used to keep track of a certain counter. It should be unique for each counter. A good choice is the URL of the page on which the counter image is located.
    • increase=number; default 1
      Specifies the number by which the counter should be increased. This can be used to check how many times a certain page was visited without increasing the counter. In that case specify increase=0.
      Resetting a certain counter is also possible this way by specifying a negative number here.
    • show=NO
      In case you would like to keep track of the number of accesses to a certain page without showing the counter image, specify the above argument.
    • debug=ON
      The above is a special argument which can used to check the correct working of the software. You should NOT specify this argument inside a HTML-page. Instead it should be used directly by calling the nph-count program from the 'open URL' window, present in most WWW-browsers, using something like the following:
      http://localhost/cgi-bin/nph-count?link=dummy&debug=ON
      This will return an on-line generated HTML-page giving information about possible problems with the installed counter software.

  2. What to add in a HTML-page ?
    To activate a counter in a certain HTML-page add something like the following:
    < IMG SRC="/cgi-bin/nph-count?arg1=value1&arg2=value2&arg3=value3">
    where arg1,2,3 are any of the supported arguments.
    NOTE: do not specify the debug argument inside a HTML-page.

  3. How to keep track of a page without anybody knowing ?
    In the page you would like to monitor insert something like the following:
    < IMG SRC="/cgi-bin/nph-count?link=link_arg&show=NO">
    and on a different HTML-page where you would like the check the counter regularly:
    < IMG SRC="/cgi-bin/nph-count?link=link_arg&increase=0">

  4. How to reset a certain counter to zero ?
    If you would like to reset a counter to zero, check the counter value and the link argument you used in a HTML-page and open the following URL directly (i.e. by typing it in, in the 'open URL' box):
    http://localhost/cgi-bin/nph-count?link=link_arg&increase=-value
    This will reset the counter to zero (note: the counter value can not go negative).

  5. Can people from the rest of the Internet (ab)use the counter ?
    The current version of the counter program doesn't have access control incorporated yet. This means that anyone could maintain a counter on your machine. However, this imposes no security problem for your machine. The next version of the package will have a possibility to restrict who is allowed to start a counter on your server.

  6. What's the size of the resulting output image ?
    The program will return a GIF-image of 20 pixels high and 15 * width pixels wide. This can used to your advantage by specifying the HEIGHT and WIDTH inside the HTML-page. By doing this, during retrieval of the page, the WWW-browser can allocate space for the image while displaying the remainder of the page.
    Example:
    < IMG SRC="/cgi-bin/nph-count?width=5&link=dummy" WIDTH=75 HEIGHT=20>


© Copyright, 1995. All rights reserved
Heini Withagen
heiniw@dhp.nl