I couldn't find anything concrete while searching, but while looking at the error logs on my zend server it looks as if web crawlers are modifying various server variables to what seem to be simply inaccurate. It seems to create a sub-domain under my domain, but this sub-domain does not actually exist.
If the actual domain name is www.mydomain.com I get the following values:
'SERVER_NAME' => 'www.arbitraryValue.mydomain.com'
'HTTP_HOST' => 'www.arbitraryValue.mydomain.com'
'SCRIPT_URI' => 'http://www.arbitraryValue.mydomain.com/segment1/segment2/segment3/page.php'
For all of these instances I've noticed the HTTP_USER_AGENT reports these as web crawlers. I've got these incidents from various web crawlers including Google, not just one.
Is this typical behavior of web crawlers? Or should I be concerned about potential Server variable/user agent spoofing?
As far as spoofing I've found this question useful, but if this is typical behavior of web crawlers then I don't have to go down that rabbit hole.
