A user agent is a computer program representing a person, for example, a browser in a Web context.
Besides a browser, a user agent could be a bot scraping webpages, a download manager, or another app accessing the Web. Along with each request they make to the server, browsers include a self-identifying User-Agent HTTP header called a user agent (UA) string. This string often identifies the browser, its version number, and its host operating system.
Spam bots, download managers, and some browsers often send a fake UA string to announce themselves as a different client. This is known as user agent spoofing.
A typical user agent string looks like this: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:35.0) Gecko/20100101 Firefox/35.0".
For compatibility, it adds strings like HTML, like Gecko and Safari. The Opera browser is also based on the Blink engine, which is why it almost looks the same, but adds “Or/
Your browser sends the user agent to every website you connect to. There is no conventional way of writing an user agent string as different browsers use different formats and many web browsers load a lot of information onto their user agents.
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During the first browser war, many web servers were configured to send web pages that required advanced features, including frames, to clients that were identified as some version of Mozilla only. Other browsers were considered to be older products such as Mosaic, Cello, or Samba, and would be sent a bare-bones HTML document.
Automated agents are expected to follow rules in a special file called robots.txt “. The popularity of various Web browser products has varied throughout the Web's history, and this has influenced the design of websites in such a way that websites are sometimes designed to work well only with particular browsers, rather than according to uniform standards by the World Wide Web Consortium (W3C) or the Internet Engineering Task Force (IETF).
Websites often include code to detect browser version to adjust the page design sent according to the user agent string received. Thus, various browsers have a feature to cloak or spoof their identification to force certain server-side content.
For example, the Android browser identifies itself as Safari (among other things) in order to aid compatibility. User agent sniffing is the practice of websites showing different or adjusted content when viewed with certain user agents.
An example of this is Microsoft Exchange Server 2003's Outlook Web Access feature. When viewed with Internet Explorer 6 or newer, more functionality is displayed compared to the same page in any other browsers.
Web browsers created in the United States, such as Netscape Navigator and Internet Explorer, previously used the letters U, I, and N to specify the encryption strength in the user agent string. Until 1996, when the United States government disallowed encryption with keys longer than 40 bits to be exported, vendors shipped various browser versions with different encryption strengths.
^ a b RFC 3261, SIP: Session Initiation Protocol, IETF, The Internet Society (2002) ^ RFC 7231, Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content, IETF, The Internet Society (June 2014) ^ Net news Article Format. Browser Versions Carry 10.5 Bits of Identifying Information on Average “, Electronic Frontier Foundation, 27 January 2010.
I've been rejected until I come back with Netscape” ^ “Android Browser Reports Itself as Apple Safari”. ^ User Agent String explained: Android WebKit Browser”.
Mozilla/5.0 (Linux; U; Android 2.2; ends; HTC_DesireHD_A9191 Build/FRF91) Apple WebKit/533.1 (HTML, like Gecko) Version/4.0 Mobile Safari/533.1 ^ Emberton, Stephen. ^ “Chrome Phasing out Support for User Agent ".
Essentially, an user agent is a way for a browser to say “Hi, I’m Mozilla Firefox on Windows” or “Hi, I’m Safari on an iPhone” to a web server. The user agent string identifies the browser as IE 9 with the Trident 5 rendering engine.
The plot thickens: Chrome is pretending to be both Mozilla and Safari. To understand why, we’ll have to examine the history of user agents and browsers.
(Yes, this means that you can sometimes bypass registration screens by setting your user agent to Google bot.) He's written about technology for nearly a decade and was a World columnist for two years.
Chris has written for The New York Times, been interviewed as a technology expert on TV stations like Miami's NBC 6, and had his work covered by news outlets like the BBC. Since 2011, Chris has written over 2,000 articles that have been read more than 500 million times---and that's just here at How-To Geek.
Most fields using product tokens also allow sub-products which form a significant part of the application to be listed, separated by white space. Here are two examples of UAS used by Samsung Galaxy S6 and macOS X-based computer using a Safari browser.
One of the main use cases of an user agent parser is to identify and handle requests from certain types of traffic. This is particularly useful when dealing with the wide spectrum of devices in use today, and allows you to get as fine-grained as you like with your content targeting strategy.
Outside of web optimization, this has obvious applications to the advertising sector, where the device can be useful as a criterion for targeting. The other main use case is around analytics, which can be very deep with a good device description repository.
Bots and crawlers have User -Agents too, and can be identified accurately by a good device detection solution. Security is the other big area where being aware of the nature of traffic hitting your services is extremely important.
These range from search engines to link checkers, SEO tools, feed readers, scripts and other nefarious actors at large in the web landscape. Being able to distinguish between these different sources can provide significant savings in IT costs by detecting and identifying bot traffic to your site.
You would need to constantly update your regex rules as new devices, browsers and OSs are released, and then run tests to see if the solution still works well. At some point, this becomes a costly maintenance job, and, over time, a real risk that you are misdirecting or failing to detect much of your traffic. Accurately parsing User -Agents is one problem.
Device Atlas uses a Patricia train data structure to determine the properties of a device in the quickest and most efficient way. This is the reason why major companies rely on established solutions built on proven and patented technology like Device Atlas.
The purpose of this article is to provide a quick and easy reference to the critical headers in a SIP INVITE. The Request URI is the contact information of the next hop in the call route.
The Form header field indicates contact information of the initiator of the SIP INVITE request, Alice in this case. The To header field contains the information about the called party or the recipient of the request, Bob in this example.
The Call-ID header field is a unique ID identifying the SIP call. It includes the contact information of the device that forwards the INVITE, and also the reason for diversion.
This SIP header is considered obsolete, but is still used to convey the calling telephone number and source IP address. The P-Charge-Info header is used to convey billing information about the party to be charged.
It describes the source device that generated the SIP INVITE. This is the source IP address and connection type for the audio stream.
This was one of the simpler SIP INVITE requests, and it could be more complex depending on the call flow. The SIP INVITE is an important request method, and the information it contains could be used not just for session initiation, but also for such crucial applications as fraud detection.
SIP Analytics ® inspects each call before it begins. It’s the fastest, most precise method available to detect and prevent telecom toll fraud.
And behold, then came a new web browser known as “Mozilla”, being short for “Mosaic Killer,” but Mosaic was not amused, so the public name was changed to Netscape, and Netscape called itself Mozilla/1.0 (Win3.1), and there was more rejoicing. And so Microsoft made their own web browser, which they called Internet Explorer, hoping for it to be a “Netscape Killer”.
And Microsoft grew impatient, and did not wish to wait for webmasters to learn of IE and begin to send it frames, and so Internet Explorer declared that it was “Mozilla compatible” and began to impersonate Netscape, and called itself Mozilla/1.22 (compatible; MSI 2.0; Windows 95), and Internet Explorer received frames, and all of Microsoft was happy, but webmasters were confused. And Microsoft sold IE with Windows, and made it better than Netscape, and the first browser war raged upon the face of the land.
And Gecko began to multiply, and other browsers were born that used its code, and they called themselves Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; RV:1.7.2) Gecko/20040825 Camino/0.8.1 the one, and Mozilla/5.0 (Windows; U; Windows NT 5.1; DE; RV:18.104.22.168) Gecko/20071008 Monkey/1.0 another, each pretending to be Mozilla, and all of them powered by Gecko. And Microsoft feared Firefox greatly, and Internet Explorer returned, and called itself Mozilla/4.0 (compatible; MSI 8.0; Windows NT 6.0) and it rendered good code, but only if webmasters commanded it to do so.
How can I set or change user agent with curl command on Linux or Unix like system? This page shows how to set or change curl command user agent.
You can use curl command get headers or view source code of any website URL. Others may just display different content based on operating system, browser version, and user agent.
Curia renamed this task from Add user _ agent _map field to EventCapsule to Change sergeant field to user _ agent _map in EventCapsule.