Short url service
Under a URL shortening , English URL shortener , refers to a service that for arbitrary URLs of existing Web pages a second, alternative URL provides. This alias URL leads to the call of the original website via an HTTP redirect. The alias, also known as short URL , URL alias or short link , usually consists of a few (ASCII) letters or numbers. This is used to provide short and unproblematic aliases (easier to remember, faster to enter, ...) for bulky, large and problematic URLs (containing special characters). Such URLs are mainly found on websites that operate with database variables.
The use of short URLs is also widespread in microblogging services and status reports in social networks , both of which only allow a limited number of characters per message. "Redirect Checker" can be used to display the redirection of short links without visiting them.
The offer usually consists of three parts:
- On the provider's homepage, a short alias can be created in a web form by specifying the desired target URL. Some short URL services also offer a bookmarklet that allows a short URL to be generated for the page currently being visited without first having to copy the original link from the URL line of the web browser.
- Each call to the alias URL is then automatically forwarded to the previously specified destination URL.
- Most providers also provide access statistics for the individual short URLs.
Some short link services also provide additional functions. Examples of this are the creation of user-defined short links, short links with virus protection functions, the creation of QR codes for short links or the creation of password-protected short URLs (see also known and special services ).
Original-URL: http://de.wikipedia.org/wiki/Portal:Wissenschaft URL-Alias: http://w.wiki/VF
The short URL contains a character string that serves as a unique identifier for the operator of the short URL service. This can be used to determine the long URL in the operator's database. The web server then sends an HTTP status code in the header to the client and informs the browser of the new address. Such a header could look like this:
HTTP/1.0 301 Moved Permanently Connection: keep-alive Location: http://de.wikipedia.org/wiki/Portal:Wissenschaft Content-type: text/html Content-Length: 0 Date: Sat, 27 May 2006 17:01:45 GMT Server: ExampleURL/1.5
Some short URL services now offer that you can also give the new link your own identifier. For example, the long link above can also be shortened as follows:
Original-URL: http://de.wikipedia.org/wiki/Portal:Wissenschaft URL-Alias: http://example.org/wissenschaft
This enables the user to recognize the shortened link and an optimal recording of search engines. One possibility to take action against improper use is the preview function of some providers. Another parameter in the short URLs ( e.g. preview ) shows the link user the long version of the desired address. Many providers finance themselves through advertising on such preview pages.
- URL aliases hide the actual link target from the user. A "real" link contains various information, such as the name of the server, the directory or the file, with which its trustworthiness can be better assessed. In the case of URL aliases, the visitor may be redirected to a page that he may not or may not be allowed to visit without his consent. This fact can be misused to unintentionally lure people to pages that compromise the user's computer via security gaps in the web browser , or to initiate cross-site request forgery . For this reason, many short URL providers offer a preview link on request, which does not take you directly to the destination, but first to an intermediate page on which further information about the destination link is given, for example:
Original-URL: http://de.wikipedia.org/wiki/Portal:Wissenschaft URL-Alias mit Vorschau: http://preview.example.com/o5lao
- The providers of the short URL services are not protected from attacks either: The short URL service Cli.gs was attacked in July 2009, hackers penetrated the database of the website and all had around 2.2 million short URLs redirected to another page. Such attacks can lead to the fact that all links of a provider z. For example, refer to pages on which malware is applied, which then contaminates the user's PC.
- URL aliases are usually provided free of charge. However, if a provider decides to commercialize its service or if a provider ceases to operate, all of that provider's URL aliases will suddenly become inoperable. Since the sustainability of the information is therefore not guaranteed, it is recommended to refrain from using alias URLs , especially in web forums or in Usenet , as the articles written there are sometimes archived for decades. The 301Works.org initiative , behind which the founder of the internet archive archive.org is, wants to ensure that the short URLs remain functional in the long term - providers of short URLs can participate in this initiative.
- In principle, the forwarding operator can create central user profiles in which the pages accessed are linked.
- A security problem from the company's point of view is that in-house deep links to protected content are collected in the external database of the short URL service provider. The problem is that even if the content is protected as in an extranet or company wiki , some conclusions can be drawn about the content of the documents based on the link title (e.g. about a customer if his name is part of the Url is).
Well-known and special services
The Bit.ly service operated from the USA is the most widely used short URL service worldwide.
In addition to this operator, there are many other short link providers, some of whom also try to minimize the risks of short links, for example by installing malware and phishing protection functions. The short link service t1p.de , which is operated from Germany and which also includes other domains, also offers the option of activating an optional dereferrer protection, which is intended to protect the privacy of users. It is also possible to protect short links with a password, to restrict their validity period and to generate a QR code that matches the short URL .
The YoURLS service, developed in the PHP programming language , can be installed on a web server to run your own short URL service.
The Wikimedia URL Shortener for any pages from the projects hosted by the Wikimedia Foundation has been in operation since April 2019.
Despite the efforts of the providers mentioned, not all of the disadvantages of short links can be eliminated by technical measures, which is why their use remains controversial despite a higher level of security.
- ↑ Short URLs: The risky game with the Twitter links on chip.de
- ↑ 301Works.org
- ↑ Short URL services: useful and risky on seibert-media.net 2008
- ↑ When It Comes To URL Shorteners, bit.ly Is Now The Biggest . techcrunch.com, accessed June 24, 2012
- ↑ Wikimedia URL Shortener Description - Special page or as a short URL https://w.wiki/4e
- ↑ Update from November 25, 2019, accessed April 5, 2020