How to block libwww-perl under Apache web server

Use mod_rewrite and .htaccess file to block user agent libwww-perl. Open your .htaccess file and add rule as follows:

SetEnvIfNoCase User-Agent "^libwww-perl*" block_bad_bots
Deny from env=block_bad_bots


How do I verify that User-Agent libwww-perl is blocked?

Download this perl script on your own workstation. Replace http://your-website.com/ with your site name:
$req = HTTP::Request->new(GET => 'http://your-website.com/');
Save and execute perl script:
$ chmod +x test-lwp.pl
$ ./test-lwp.pl
Output:

Error: 403 Forbidden

You should see 403 Forbidden error as your user-agent is blocked by server configuration.

Please note that blocking by user agent can help, but spammers spoof user agents. My personal experience shows that blocking libwww-perl saves bandwidth and drops potential threats by 50-80%.

Taken from this site.