For enabling server to listen on different ports we can make the changes in file port.conf in Debian/Ubuntu based linux server. The path where we can find the ports.conf file is below:

1-> Debian/ Ubuntu :   {  /etc/apache2/ports.conf } 

let us say we want Apache2 to listen on port 8181 instead of 80. Here we will change the configuration option as below:

Listen 8181

We can also enable Apache2 to listen on both ports 80 and 8181 with the following changes:

Listen 80

Listen 8181

In this way we can enable Apache2 to listen on as many port as per the requirement. After we are done with the above changes, restart Apache2 server:

sudo service apache2 restart

For enabling server to listen on different ports we can make the changes in file httpd.conf in Centos/Fedora based linux server. The path where we can find the httpd.conf file is below:

2-> Centos/ Fedora :   {  /etc/httpd/conf/httpd.conf } 

Now find the line that reads in file httpd.conf

Listen 80

Now we will force httpd to listen port 80 and 8181 by writing

Listen 80 Listen 8181

Now save and close the httpd file and restart the httpd.

/etc/init .d/httpd restart

For more information see the link below:

Link: http://www.cyberciti.biz/faq/fedora-rhel-centos-configure-httpd-listen-multipleports/