This apache module will limit number of IP connections from a particular IP to a specific domain or files. You can see the project home page from  http://dominia.org/djao/limitipconn2.html . This module have apache 1.3 , 2.x and 2.2.x packages.

wget http://dominia.org/djao/limit/mod_limitipconn-0.23.tar.bz2

tar -xjf mod_limitipconn-0.23.tar.bz2

cd mod_limitipconn-0.23/

/usr/local/apache/bin/apxs -cia mod_limitipconn.c

/scripts/rebuildhttpdconf

cat >> /usr/local/apache/conf/mod_limitipconn.conf << EOF

LoadModule limitipconn_module modules/mod_limitipconn.so

ExtendedStatus On

<IfModule mod_limitipconn.c>

# Set a server-wide limit of 10 simultaneous downloads per IP,

# no matter what.

MaxConnPerIP 10

<Location /somewhere>

# This section affects all files under http://your.server/somewhere

MaxConnPerIP 3

# exempting images from the connection limit is often a good

# idea if your web page has lots of inline images, since these

# pages often generate a flurry of concurrent image requests

NoIPLimit image/*

</Location>

<Directory /home/*/public_html>

# This section affects all files under /home/*/public_html

MaxConnPerIP 1

# In this case, all MIME types other than audio/mpeg and video*

# are exempt from the limit check

OnlyIPLimit audio/mpeg video

</Directory>

</IfModule>

EOF
Now edit the file  /usr/local/apache/conf/includes/pre_main_global.conf  and add the following lines

Include “/usr/local/apache/conf/mod_limitipconn.conf”

Now restart apache

You can check whether the module loaded or not using the following command.

/usr/local/apache/bin/httpd -M | grep limitipconn_module