Inline linking and HTTP
The technology behind the World Wide Web, the<img>
tags which supply the <img src="picture.jpg" />
). It also permits absolute URLs that refer to images hosted on other servers (<img src="http://www.example.com/picture.jpg " />
).
When a browser downloads an HTML page containing such an image, the browser will contact the remote server to request the image content.
Common uses of linked content
The ability to display content from one site within another is part of the original design of the Web'sslashdot.org
; individual stories on servers such as games.slashdot.org
or it.slashdot.org
; and serves images for each host from images.slashdot.org
.
* An article on one site may choose to refer to copyrighted images or content on another site via inline linking, which may avoid rights and ownership issues that copying the original files could raise. However, this practice is generally discouraged due to resulting bandwidth loading of the source, and the source provider is often offended because the viewer is not seeing the whole original page, which provides the intended context of the image.
* Many web pages include <img>
tag may specify a URL to a CGI script on the ad server, including a string uniquely identifying the site producing the traffic, and possibly other information about the person viewing the ad, previously collected and associated with a cookie. The CGI script determines which image to send in response to the request.
* Some websites hotlink from a faster server to increase client loading speed.
* Controversial uses of inline linking
The blurring of boundaries between sites can lead to other problems when the site violates users' expectations. Other times, inline linking can be done for malicious purposes. * Content sites where the object is stored and from which it is retrieved may not like the new placement. * Inline linking to an image stored on another site increases the bandwidth use of that site even though the site is not being viewed as intended. The complaint may be the loss of ad revenue or changing the perceived meaning through an unapproved context. * Cross-site scripting and phishing attacks may include inline links to a legitimate site to gain the confidence of a victim. * Pay-per-content services may attempt to restrict access to their content through complex scripting and inline linking techniques. * Inline objects can be used to perform drive-by attacks on the client, exploiting faults in the code that interprets the objects. When an object is stored on an external server, the referring site has no control over if and when an originally beneficial object's content is replaced by malicious content. * The requests for inline objects usually contain the referrer information. This leaks information about the browsed pages to the servers hosting the objects (see web visitor tracking).Prevention
Client side
Most web browsers will blindly follow the URL for inline links, even though it is a frequent security complaint. Embedded images may be used as a web bug to track users or to relay information to a third party. Many ad filtering browser tools will restrict this behavior to varying degrees.Server side
Some servers are programmed to use the HTTP referer header to detect hotlinking and return a condemnatory message, commonly in the same format, in place of the expected image or media clip. Most servers can be configured to partially protect hosted media from inline linking, usually by not serving the media or by serving a different file. URL rewriting is often used (e.g., mod_rewrite withCopyright issues raised by inline linking
The most significant legal fact about inline linking, relative to copyright law considerations, is that the inline linker does not place a copy of the image file on its own Internet server. Rather, the inline linker places a pointer on its Internet server that points to the server on which the proprietor of the image has placed the image file. This pointer causes a user's browser to jump to the proprietor's server and fetch the image file to the user's computer. US courts have considered this a decisive fact in copyright analysis. Thus, in ''Google does not...display a copy of full-size infringing photographic images for purposes of the Copyright Act when Google frames in-line linked images that appear on a user’s computer screen. Because Google’s computers do not store the photographic images, Google does not have a copy of the images for purposes of the Copyright Act. In other words, Google does not have any “material objects...in which a work is fixed...and from which the work can be perceived, reproduced, or otherwise communicated” and thus cannot communicate a copy. Instead of communicating a copy of the image, Google provides HTML instructions that direct a user’s browser to a website publisher’s computer that stores the full-size photographic image. Providing these HTML instructions is not equivalent to showing a copy. First, the HTML instructions are lines of text, not a photographic image. Second, HTML instructions do not themselves cause infringing images to appear on the user’s computer screen. The HTML merely gives the address of the image to the user’s browser. The browser then interacts with the computer that stores the infringing image. It is this interaction that causes an infringing image to appear on the user’s computer screen. Google may facilitate the user’s access to infringing images. However, such assistance raised only contributory liability issues and does not constitute direct infringement of the copyright owner’s display rights. ...While in-line linking and framing may cause some computer users to believe they are viewing a single Google webpage, the Copyright Act...does not protect a copyright holder against uchacts....
See also
* Copyright aspects of hyperlinking and framing * Deep linkingReferences
{{Authority control Internet terminology File sharing Hypertext Internet ethics