Information about the visitor avaialble to a web site provider

Further Web Page and Network Handling example from a Well House Consultants training course
More on Further Web Page and Network Handling [link]

This example is described in the following article(s):
• PHP data sources - other web servers, large data flows, and the client (browser) - [link]

If you're searching for a page where you can try this code, select here

This example references the following resources:
http://www.wellho.net/mouth/1798_What-does-an-browser-understand-What-does-an-HTML-document-contain-.html
http://www.wellho.net/forum/Writing-PHP/Which-browser-is-being-used.html
http://www.wellho.net/mouth/2135_What-features-does-this-visitors-browser-support-PHP-.html
http://www.wellho.net/mouth/767_Finding-the-language-preference-of-a-web-site-visitor.html
http://www.wellho.net/mouth/2884_Hotlinked-images-onto-adult-material-sites.html
http://www.wellho.net/mouth/1976_Where-is-this-IP-address-IPv4-and-IPv6.html

Source code: about_you.php Module: H112


<?php

$report = array (
        "HTTP_USER_AGENT" => "Your Browser (1)",
        "HTTP_ACCEPT_LANGUAGE" => "Languages you prefer (2)",
        "HTTP_REFERER" => "The page you came from (3)",
        "REMOTE_ADDR" => "Your IP address (4)",
        "REQUEST_URI" => "The page you asked for (5)",
        "REQUEST_TIME" => "When you called up this page (6)");

function cell($contains) {
        if ($contains) {
                $rv = "<td>".htmlspecialchars($contains)."</td>";
        } else {
                $rv = "<td>-</td>";
        }
        return $rv;
}

$html = '<table cellpadding="3" border="1">';
foreach (array_keys($report) as $item) {
        $html .= "<tr>".
                cell($report[$item]).
                cell($_SERVER[$item]).
                "</tr>";
        }
$html .= "</table>";

# ---------------------------------------------------
?>
<html>
<head>
<title>About Your visit to us!</title>
</head>
<body>
<h1>A bit about <i>you</i></h1>
The $_SERVER superglobal in PHP contains a number of useful pieces of information that give
<i>an indication</i> about the visitor; as much / most of this information is supplied by the
visitor, it may be missing, it can be misleading, and it's possible for it to be falsified.<br />
<br /><?= $html ?><br />
<hr />
<b><u>Now --- what does that mean?</u></b><br /><br />
<b>(1) - HTTP_USER_AGENT => Your Browser. </b><br />
This is a string of text passed from your browser to the server to tell it
what type of browser is in use.  As well as helping you identify the common
browser types, you can identify the robots that roam the web indexing pages
for search engines, and you can very often spot incursion attacks and other
automata of various types too. The value is useful within the "real person"
group to help you spot who is likely to have flash capabilities, who can
correcly format phone: URLs, etc, so that you can adapt the page for them.
See <a href=http://www.wellho.net/mouth/1798_What-does-an-browser-understand-What-does-an-HTML-document-contain-.html>[here]</a>
and <a href=http://www.wellho.net/forum/Writing-PHP/Which-browser-is-being-used.html>[here]</a> and i
<a href=http://www.wellho.net/mouth/2135_What-features-does-this-visitors-browser-support-PHP-.html>[here]</a>.
<br /><br />
<b>(2) - HTTP_ACCEPT_LANGUAGE => Languages you prefer.</b><br />
This will tell you the nationallity and preferred language of your visitor if (s)he
has set it ... so that you can send out your response in English ... or French, Spanish,
Polish or Chinese if your web site has the capability.
See <a href=http://www.wellho.net/mouth/767_Finding-the-language-preference-of-a-web-site-visitor.html>[here]</a>
<br /><br />
<b>(3) - HTTP_REFERER => The page you came from.</b><br />
This is the URL of the previous page that the user was on, or in the case of images
and other files included <i>within</i> a page the URL of that page that called the
resource up. If empty, the request is by someone typing in a URL themselves, following
a link from an emal, or an automata that's indexing your site.   The value is especially
useful in telling you where new arrivals have come from - with a search engine, you can
tell what search term the user entered that brought him to you, and with an image you
can tell if it's been hotlinked from someone else's site, stealing your bandwidth and perhaps
your copyright. See <a href=http://www.wellho.net/mouth/2884_Hotlinked-images-onto-adult-material-sites.html>[here]</a>
for an example of this in use.
<br /><br />
<b>(4) - REMOTE_ADDR => Your IP address.</b><br />
The IP address of the browser - but (be careful) this may sometimes be an intermediate
proxy if the visitor is taking trouble to hide who (s)he is.  More about this (and how to look it up)
<a href=http://www.wellho.net/mouth/1976_Where-is-this-IP-address-IPv4-and-IPv6.html>[here]</a>
<br /><br />
<b>(5) - REQUEST_URI => The page you asked for.</b><br />
The page you asked for.  AT first glance, this might look pretty obvious as you'll be able
to find the name of the script you're running ... but in practise it's not that starightforward.
Using page redirection through mod_rewrite, you'll find you often run a piece of code held
in a file who's name is different to the page name requested, and that lots of requests
all map to the same script.   This value lets you backtrack.
<br /><br />
<b>(6) - REQUEST_TIME => When you called up this page.</b><br />
The time, in seconds, from 1.1.1970 that the page was called up.
<br /><br />
</body>
</html>

Learn about this subject

This module and example are covered on the following public courses:
* Learning to program in PHP
* PHP Programming
* PHP Programming
* Learning to program in PHP
Also available on on site courses for larger groups

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