.htaccess Allow All from Specific User Agent

If you don't want to use mode_rewrite, with Apache 2.4 you can use something similar to this:

<Location />
                AuthType Basic
                AuthName "Enter Login and Password to Enter"
                AuthUserFile /home/content/html/.htpasswd
                <If "%{HTTP_USER_AGENT} == 'myuseragent'">
                Require all granted
                </If>
                <Else>
                Require valid-user
                Require ip 12.34.567.89
                </Else>
</Location>

I just want to allow ONE SPECIFIC user agent rather than trying to block all

Here's my config to allow only wget:

SetEnvIf User-Agent .*Wget* wget

Order deny,allow
Deny from all
Allow from env=wget

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

Htaccess SetEnvIf and SetEnvIfNoCase Examples

Allow from and Rewrite* are directives from two different Apache's modules.

The first one is mod_authz_host and the other from mod_rewrite.

You can use mod_rewrite to do what you want:

RewriteEngine on
RewriteCond %{HTTP_USER_AGENT} !=myuseragent
RewriteRule .* - [F,L]