How to block libwww-perl user agent other than W3C version

How to block all libwww user agents other than the W3C version

[wdfw]

We currently block the libwww-perl user agent in our .htaccess. Its main use appears to be for script kiddies to sniff around for injection vulnerabilities.

Unfortunately, however, W3C uses it for their online link checker.

Is it possible to construct a RewriteCond that will block all libwww-perl user agents UNLESS it contains "W3C-checklink"?

Thanks!

[tangor]

Put that as a "pass" first then kill all libwww which follow, however, that's a pretty easy thing for the script kiddies to spoof... so might want to look at other criteria.

[wdfw]

Thanks Tangor. As I am still quite the noob with mod_rewrite, would you mind providing the code?

Here is a snippet from our .htaccess

<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{REQUEST_URI} !^/security.php
RewriteCond %{HTTP_USER_AGENT} (.*)Havij(.*) [NC,OR]
RewriteCond %{HTTP_USER_AGENT} (*)libwww-perl(*) [NC,OR]
etc., etc.,
RewriteRule .* [#*$!.#*$!.com...] [R=301,L]
</IfModule>

[wilderness]

The version numbers may require correction before use.

#reads EXCEPT checklink OR except request for security.php
RewriteCond %{HTTP_USER_AGENT} !^/W3C-checklink/4\.5 [4/.160] libwww-perl/5\.823 [OR]
RewriteCond %{REQUEST_URI} !^/security.php