xinetd

xinetd—the name is an acronym for “extended Internet services daemon.” The xinetd program accomplishes the same task as the regular inetd program: It helps to start programs that provide Internet services. Instead of having such programs automatically start up during system initialization and remain unused until a connection request arrives, xinetd instead stands in the gap for those programs and listens on their normal service ports. As a result, when xinetd hears a service request meant for one of the services it manages, it then starts or spurns the appropriate service.


NOTE Your Linux distribution might not have the xinetd software installed out of the box. The xinetd package can be installed with yum on a Fedora distro (or RHEL, Centos) by running

yum install xinetd

On a Debian-based distro like Ubuntu, xinetd can be installed using APT by running
sudo apt-get install xinetd


source :- Steve shah & Wale soyinka