A slow loris attack is one where an IP will connect to your apache server and clog up all child processes with it's specially formed requests (I won't get into the details as to how).
The solution is to install mod_antiloris to only allow a certain number of simulatenous connections per IP at a time (I believe they set it to 5 by default)
The registered apache mod_antiloris module is listed here:
http://modules.apache.org/search.php?id=1783
Quick install instructions:
cd /root
wget http://files.directadmin.com/services/all/mod_antiloris/installoris
chmod 755 installoris
./installoris
Note that this module is for apache 2.x, and not 1.3.