It will look at the client IP and check it in one or several DNSBL servers and return
a 403 Forbidden page to the client.
Download the package: here
Follow the steps below to compile and install the package.
# tar -zxvf mod_defensible-1.4.tar.gz
# cd mod_defensible-1.4/
# make install
You can use --with-udns to enable udns (asynchronous resolver library) usage, which should be faster. However, this is not mandatory.
Open (apache configuration file) apache2.conf and go to the end where the virtual hosts are configured, and put the mod_defensible configuration right before the virtual hosts:
# Activate DNSBL usage
# Specify DNSBL servers
DnsblServers xbl-bl.spamhaus.org. mydnbl.server.org.
With udns support, you can also use:
# Specify another nameserver to use instead of default system resolver
Restart Apache afterwards: /etc/init.d/apache2 restart
That's it. If an IP address which is blacklisted tries to access your webserver, it will receive an HTTP error 403.