Since some uas have more than one nameversion phrase i use an ordered array to define the precedence. However, if you want to gather the information or manipulate the data, it would be better to use a serverside scripting language, such as perl. The useragent header contains a freeform ascii string that should uniquely identify the user agent making the request. Because of this you have been provided a limited functionality version of prenticenet. Browsers continue to send horrid user agent strings like this because there are still websites that use user agent sniffing even modern ones that do it and some of these may never be updated. The browsers, desiring to support all content on the internet, must then have this horrid user agent in order to do so. What is the standard format for a browsers useragent string. This document is the official mozilla useragent string specification.
This sounds simple, but user agents have become a mess over time. The following is an abridged version of the history of user agent strings as it appears in my book, professional javascript for web developers, 2nd edition. At least thats not just because of a user agent string. This shortcut is the starting point for the chaos in useragent string. This is a major revision of the original, obsolete, useragent string proposal. It is common practice for this string to name the user agent s hardware and browser, and versions. A browsers user agent string ua helps identify which browser is being used, what version, and on which operating system. Tech support scams are an industrywide issue where scammers trick you into paying for unnecessary technical support services. A user agent is a particular string of characters in each browser that allows acts as an identification agent. It may refer to an email client see messaging system, a web browser, search engine spider or any other program in the user s machine that is accessing a service on the internet see user agent string. Based on your user agent string, we have decided that you have an older browser, are a mobile device, or are a robot. Useragent string shared techniques wiki for the w3c. Useragent examples,user agent types,user agent request.
When you visit a web page, your browser sends the user agent string to the server hosting the site that you are visiting. Device detection analyzes the user agent ua string sent by the browser. I use pure javascript rendering on the client side, and feature detection is not enough. Internet explorer 11s many useragent strings ieinternals. Udger ua list database includes detailed information about every single user agent and operating system. Using this data, a website can assess the capabilities of your computer, optimizing a pages performance and display. In computing, a user agent is software a software agent that is acting on behalf of a user, such. This string often identifies the browser, its version number, and its host operating. Dec 29, 2017 there are a few ways to access user agent information. The useragent tells the server what the visiting device is among many other things and this information can be used to determine what content to return. For example, the useragent string might be used by a web server to choose variants. And to do that, you need to take a look at how the useragent string has.
In fact, that was the most common user agent string among browsers visiting the eff website during the test period. A searchable database of useragents as used by browsers, searchengines spiders and crawlers, webdirectories, download managers, link checkers, proxy servers, web filtering tools, harvesters, spambots, badbots. What do you think is the best way to parse user agent strings. The useragent header is part of the rfc7231, which is an improved version of the rfc1945, where it states the useragent requestheader field contains information about the user agent originating the request. There are two problems with the user agent that urge us to find a replacement. For historical reasons, almost every browser today sends it. Kmeleon is a fast and customizable lightweight web browser for windows, based on the rendering engine of mozilla. Besides a browser, a user agent could be a bot scraping webpages, a download manager, or another app accessing the web.
Theres no standard way of writing a user agent string, so different web browsers use different formats some are wildly different, and many web browsers cram loads of information into their user agents. Feature detection cannot detect many browser quirks. This is a major revision of the original, obsolete, user agent string proposal. For example, the nokia 6600 series sends a header like. Konqueror and webkit want to be identified as firefox. However, user agent strings are easy to spoof, so not every request using these user agent names inside of their user agent string may be coming from a real bing crawler. And so microsoft made their own web browser, which they called internet explorer, hoping for it to be a netscape killer. The history of the useragent string is marked by browsers trying to convince useragent sniffers that they are what they are not. Sep, 2017 a user agent is a string that is, a line of text identifying the browser and operating system to the web server. A user agent is a short string that web browsers and other applications send to identify themselves to web servers.
For example, the button at the beginning of this page uses javascript to display your user agent string. When you visit a webpage, the browser sends the useragent string to the. Create a mobile website create a mobile website with this easy tool. Then netscape was reborn as mozilla with a whole bunch of. The web server can use this information to provide content that is tailored for your. But fact is, for most browsers it can be set to arbitrary values by the user, it can be modified by proxies between server and client, and it can be changed or supplemented by. This is for statistical purposes, the tracing of protocol violations, and automated recognition of user agents for the sake of tailoring responses to avoid particular. User agent string provide information on application type, operating system, software vendor version and layout rendering engine.
Kmeleon is free open source software released under the gnu general public license. To provide a amazon fire tvspecific experience, test for the string amazonwebappplatform in combination with a device model that starts with aft. The user agent tells the server what the visiting device is among many other things and this information can be used to determine what content to return. Ie provides feature tokens that contains information about. This is for statistical purposes, the tracing of protocol violations, and automated recognition of user agents for the sake of tailoring responses to avoid particular user agent limitations. Nov 22, 2014 user agent sniffing is a necessary evil, even with careful use of feature detection. The contents of the user agent field vary from browser to. Sep 21, 20 if the xuacompatible has been set to ie9, ie11 should send the ie9 user agent string not the ie11 user agent string ericlaw its not clear how you imagine that would work.
When you visit a web page, your browser sends the useragent string to the server hosting the site that you are visiting. The user agent request header is a characteristic string that lets servers and network peers identify the application, operating system, vendor, andor version of the requesting user agent. History of the browser useragent string 2008 hacker news. Thats where steps in we decode your user agent string to figure out everything its saying. Sometimes abbreviated as ua, the user agent is a browser text string that is given to each website you visit. In the user agent request header field, amazon silk sends one of three user agent strings, depending on the. User agent strings typically carry information about an operating system, web browser and a basic hardware device information. Useragent string article about useragent string by the.
User agent string decoder is a decoder tool that allows translating a browser user agent string into data blocks. Digging into the data is a trove of information, broken delights, privacy insanity, etc. This is useful when you want to authenticate users using a known set of client applications, usually browsers, and allow other applications, often a set of applications that dont support authentication, to proceed without authentication. Uas can be blank, or contain custom information like a url to a site that might promote a particular browser or. Then, the web server uses the exchanged information to determine what content is presented to particular operating systems and web browsers on a. For example, if a user s product were called wikibrowser, their user agent string might be wikibrowser1. Of course this requires using a device detection solution which. It is common practice for this string to name the user agents hardware and browser, and versions. When a software agent operates in a network protocol, it often identifies itself, its application type, operating system, software vendor, or software revision, by submitting a characteristic identification string to its operating peer. User agent strings per browser, operating system, device, brand and plugin.
A searchable database of user agents as used by browsers, searchengines spiders and crawlers, webdirectories, download managers, link checkers, proxy servers, web filtering tools, harvesters, spambots, badbots. If this assumption is incorrect, please contact us and provide your user agent string. It is from my webtools project update coming soon to the repo. For more on firefox and geckobased user agent strings, see the firefox user agent string reference. This can make useragent sniffing a bit more difficult although. When reading the user agent string, do not rely on specific version numbers within the string that are subject to change when the software is updated. Your current useragent string appears to be from an. On the structure and characteristics of user agent string. Understanding browsers useragent lets start to learn. Some programmers will find legitimate uas and program their script to use such uas. Internet explorer wants to be identified as netscape 4. In an authentication rule, a request header useragent value can be used to determine if user authentication will be performed.
Uas help identify what device is currently accessing the site. The user agent allows the webserver ti to identify the operating system and the browser. However, the primary mechanism for ensuring that content is delivered in the optimal format is the user agent string. The function parses the useragent string passed as argument, and returns an array of associative arrays, each one defining a productcomment in the agent string key of the associative array are product, version, comment.
The user agent string format is currently specified by section 5. Its not until the response to that request is received that it gets the servers xuacompatible directive. The default user agent string for opera is the most logical of all modern browsers, correctly identifying itself and its version. Udger database includes detailed information about every single user agent and operating system. The useragent string is very useful because it tells you quite specific information. Depending on browser you would also get additional information. Web browser products has varied throughout the webs history, and this has.
The data supplied by the user agent string is generally used to optimize web browsing experience. Useragent string shared techniques wiki for the w3c mobile. This can include browsers that are running email applications, app web views, operating systems and, most importantly, the device itself. User agent strings and detection amazon silk aws documentation. Having the knowledge from above, user agent spoofing is used by many programmers that dont want people to know how theyre getting to the site s. Get an analysis of your or any other user agent string. Early browsers the first web browser, mosaic, was released in 1993 by the national center for supercomputing applications ncsa. The user agent requestheader field contains information about the user agent originating the request. Com has a large list of user agent strings by ua type, and offers an api. It is desirable for there to be standardization in the format of these strings, for logfile analysis and other purposes.
How to extract the os and browser from a user agent string in our logs without a splunk app or external script. Before we get into the history, it is worth stating upfront that useragent parsing is used. When feature detection apis are not available, use the ua to customize behavior or content to specific browser versions. This tool allows you to check what the latest i 6000038 will identify any user agent as. Find out what your web browser is sending in its user agent header. But fact is, for most browsers it can be set to arbitrary values by the user, it can be modified by proxies between server and client, and it can be changed or supplemented by certain libraries and other software components on the client side. Uas contain information such as the browser version, compatibility, operating system, and any modifying plugins. The above crawlers will identify themselves with the above names in the user agent string. Hi there, i cant help thinking that you give the user agent string a meaning it doesnt deserve. It may refer to an email client see messaging system, a web browser, search engine spider or any other program in the users machine that is accessing a service on. A user agent ua string is able to be used to detect what version of a specific browser is being used on a certain operating system.
Understand what information is contained in a user agent string. It may also be accessed via javascript by querying the value of eragent. You can help protect yourself from scammers by verifying that the contact is a microsoft agent or microsoft employee and that the phone number is an official microsoft global customer service number. Jan 12, 2010 one of the most controversial web browsers, as far as user agent strings are concerned, is opera. This string indicates which browser you are using, its version number, and details about your system, such as operating system and version. Find lists of user agent strings from browsers, crawlers, spiders, bots, validators and others. All the other user agent listings do a pretty average job of making it easy to browse related user agents, so when i built this listing, making this easy for users was one of the major priorities behind the design of it. For more on firefox and geckobased user agent strings.
We really need a method that definitely tells us which browser the user is using. Content providers often have complex regression test environments to ensure their pages render and behave correctly on different platforms 9, 20. The user agent header contains a freeform ascii string that should uniquely identify the user agent making the request. Useragent sniffing is a necessary evil, even with careful use of feature detection. Notice that the operating system and browser versions are extremely specific and that the user agent also includes the users preferred language. Its about the variability of user agent strings a server receives. The ua string of firefox is broken down into 4 components. Detects and show a lot of information about your browser and your installed plugins. The above demonstrate that its an unreliable way to guess what browser the user is using. He may have been born in great saling, or at least lived there for a time, because the vicar at great saling there witnessed williams 1574 will. An anonymized string created from your email address also called a hash may be provided to the gravatar service to see if you are using it. The amazon fire tv platform includes the android webview android.
Once the useragent string is parsed and we have the list of productscomments, more problems arise. If the xuacompatible has been set to ie9, ie11 should send the ie9 user agent string not the ie11 user agent string ericlaw its not clear how you imagine that would work. You can also sign up for the free api which will give you access to our user agent parser. I came across this blog which talks about the history of useragent.