What Web Browser Is Being Used?
The web browser (user agent) normally sends a string of text to identify itself, but this can be blank or many other things, and can be altered by users.
The Bots vs Browsers (robots versus web browsers) web site monitors the user agent identification strings and helpfully provides access to their valuable data. They have identified over 400,000 different user agent strings to date. You can see 5,000 unidentified that are not obviously any particular search engine robot or browser and could be accidental, mischievous or malicious.
Always treat user agent strings as untrusted, and check their length and content before using the sanitised text to display, or in decision-making logic or when writing it to a file or database. The lists for particular types of devices (e.g. the iPhone) may be useful to remind you of the range of values sent. User agent strings certainly shouldn't be used for any form of user authentication.
Posted on: 08 January 2010 at 09:18 hrs
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