Whenever a web browser is used to connect to a remote web server it includes a User Agent string that contains details about browser and operating system. This tweak allows you to add or remove additional information from this string.
Changing user agent string is needed when online security is a concern or to bypass web services access restriction for certain type of web browser.
For example, Adobe Reader download site will display different download page according to the web browser that visiting the site, limit or auto pick up Adobe Reader version for the OS type in the user agent string, force Adobe Updater to manage Adobe Reader download progress. So, by changing the user agent string, one can directly download any Adobe Reader version of any platforms or languages with Internet Explorer or Mozilla Firefox, without using the Adobe Updater or Opera web browser!
Another use for changing the user agent data is the ability to read restricted websites and forums.
Some websites & forums will not allow you to read their content without registering first. This requirement gets really annoying and frustrating when you go through it over and over again. But you might or might have not noticed is that these pages are being cached by search engines, because they’re specially designed to allow access to specific search engine’s bots. So, all we have to do is get that page to think that you’re a bot and you do that by changing your user agent. Here’s how you do it:
Mozilla Firefox:
For people using Firefox, changing their user agent is very simple. All you have to do is download and install User Agent Switcher add-on. Then you can simply add different user agents and switch between them directly from the browser.
Internet Explore:
Internet Explorer 6 SP2 on Windows 2000 and IE 7 for Windows XP:
Start > Run > Regedit
HKLM\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent
Create theVersion key of REG_SZ type (string type) or edit it if it already exists. Give it one of the following values: Firefox/2.0.0.4 for Firfox , “Googlebot/2.1 (+http://www.googlebot.com/bot.html)”, without the quotes for Google Bot.
IE7 in Windows Vista
Copy Paste the following code into Vista’s command prompt:
%windir%\System32\cmd.exe /k %windir%\System32\reg.exe ADD “HKLM\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent” /v Version /d “insert user agent here” /f
To revert back to original user agent string value:
%windir%\System32\cmd.exe /k %windir%\System32\reg.exe DELETE “HKLM\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent” /v Version /f
Note: Some services may not work correctly by changing your user agent, such as Windows update.
Opera 9.21:
- Type opera:config in the Opera address bar and press ENTER,
- Type Spoof UserAgent ID in the text-box next to Show All
- Change the Spoof User Agent ID to any one of these supported user agent string:
1 = Opera (default user agent string of Opera)
2 = Mozilla
3 = Internet Explorer
4 = Mozilla, Opera not mentioned
5 = Internet Explorer, Opera not mentioned
- Save the change made before exit and restart Opera 9.21
Commonly used user agents
Googlebot 2.1:
* Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
* Googlebot/2.1 (+http://www.googlebot.com/bot.html)
* Googlebot/2.1 (+http://www.google.com/bot.html)
Slurp, Yahoo Bot:
* Mozilla/5.0 (compatible; Yahoo! Slurp; http://help.yahoo.com/help/us/ysearch/slurp)
* YahooFeedSeeker/1.0 (compatible; Mozilla 4.0; MSIE 5.5; http://my.yahoo.com/s/publishers.html)
* Yahoo-MMCrawler/3.x (mms dash mmcrawler dash support at yahoo dash inc dot com)
Firefox:
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.8.1.11) Gecko/20071127 Firefox/2.0.0.11
Opera:
Opera/9.20 (Windows NT 6.0; U; en)
IE 7:
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)
To view your current Agent String click here, you’ll also find a list of all user agents by following that link.