.htaccess Allow All from Specific User Agent
snippet in htaccess

.htaccess Allow All from Specific User Agent

user9398

SetEnvIfNoCase User-Agent .*google.* search_robot
SetEnvIfNoCase User-Agent .*yahoo.* search_robot
SetEnvIfNoCase User-Agent .*bot.* search_robot
SetEnvIfNoCase User-Agent .*ask.* search_robot

Order Deny,Allow
Deny from All
Allow from env=search_robot