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".
While all phones come with pre-installed browsers, both Google Play and Apple App Store offer a number of alternative browsers, some focusing on speed and lightness, others on saving bandwidth and blocking ads, and an ever-increasing amount claiming to increase privacy and reduce a users' mobile digital footprint. Feel free to browse the stats for your local market using our Data Explorer tool.
For this example the organization has been configured to quarantine new types of mobile devices. The Exchange Control Panel shows the list quarantined devices but not the user agents.
After this rule has been added the iPhone 4S is able to connect to Actively, while TH 3GS and other quarantined device types still can’t. While testing this scenario I encountered an error in the Exchange Control Panel.
This error persists until you use PowerShell to remove any device access rules that are based on Sergeant. I discussed this with Microsoft, and they have opened a bug for it and will hopefully be able to issue an update that corrects the error some time in the future (the problem also exists in the Exchange 2013 Preview).
In the meantime they have confirmed that device access rules based on Sergeant are supported. Paul is a Microsoft MVP for Office Apps and Services and a Pluralsight author.
He works as a consultant, writer, and trainer specializing in Office 365 and Exchange Server. “Crawler” is a generic term for any program (such as a robot or spider) that is used to automatically discover and scan websites by following links from one webpage to another.
So knowing the user agent will help you to understand whether they are legitimate or bad bots. By analyzing these log entries, you can find out how many automated crawlers are scanning your site.
For example, if you don’t want Yandex search engine to crawl your site then add the following entries in your Robots.txt file. For example, you can instruct the server to block known bad bots by adding the below entries.