Techniques Of Deep Linking
Deep linking can be implemented in various ways. Using the most banal and formally correct is reporting within its pages, which indicate clearly that this is a link to a page of an external site.
More troublesome and insidious is the so-called framing, in which insertion of the linked page within the site using a calling frame (one of the sub-pages that make up the final page). This is a practice that tends to deceive the user, or that otherwise could lead to confusion in the browser-user, unless the site is not calling explicitly indicated that the link is directed to the page of another site. It can in fact be induced to think that the content belongs to the site of departure. A variant of framing uses the HTML element IFRAME (Inline Frame), a technique which can also pose a serious security threat, since it could allow attacks Cross-site scripting techniques. Similar results can be obtained with scripts executed by the browser.
In any case, these techniques allow users with different levels of difficulty, be aware that the page or part of the displayed page is from a different site than the departure. There are however techniques that are completely transparent to the end user: a web server program, written in PHP for example, can extract the fly page content published on an external server is embedded into a local page. You may not, except to inconsistencies of content, to distinguish the source of the page. This can lead to very dangerous situations: Think about a user opens a link to “micosoft.com” (note the name) and download the software from there …
If this hypothesis appears to be a nightmare for those who do not wish that its pages are the subject of deep linking, on the other hand is one of the reasons why there is a continuing convergence between HTTP / HTML and XML, as in XHTML. In fact, while with a page of plain text or HTML automatic extraction of parts of the content is always difficult, XML makes it possible to identify quickly and accurately the elements of the XHTML page, allowing, for example, to extract only the title . These possibilities are the basis of initiatives on the Semantic Web.
Deep Link Images
A particular case of deep linking is the linking of images or other resources that are not a page, like music or software. The syntax of HTML makes it possible to insert images with the use of the tag <img> specifying any URL as a source, which can be local or from another site. This case is the most controversial because it uses a passive disk space and connecting the remote site without the latter will derive any benefit, if only for visibility.
Some sites try to protect themselves from this type of deep linking by verifying that certain specific types of files to be retrieved only from other pages. This is usually possible using the field ‘referrer’ header of the HTTP request. This protection technique, however, besides not being effective against a determined attack and competent, does not take into account the existence of implementations of the browsers that do not send the server the field ‘referrer’. This situation, while conforming to the standard may therefore make it impossible to properly qualify the user of the site.
Study: From Wikipedia, the free encyclopedia. The text is available under the Creative Commons.