Red Hat Enterprise Linux 5 Administration Unleashed

CHAPTER 19Explaining OtherCommon NetworkServicesIN THIS CHAPTER. The xinetd Super Server. Transferring Files with FTP. Keeping Accurate Time withNTP. Creating a Network Printer withCUPSThis chapter describes the xinetd, FTP, NTP, and CUPSnetwork services including how to configure them, how toconnect to them, and what ports they use so administratorscan configure firewalls settings for them.These four services have one thing in common—when configured,they generally do not require much maintenance otherthan checking for security updates via Red Hat Network.The xinetd Super ServerNot all services have their own initialization script for starting,stopping, and checking the status of the daemon. Somenetwork services are controlled by xinetd, also known as thesuper server. Running services through xinetd allows theadministrator to utilize xinetd features such as accesscontrol, custom logging, and the incoming connection rate.The xinetd service listens on all ports used by the daemonsit controls. When a connection is requested, xinetd determinesif the client is allowed access. If the client is allowedaccess, xinetd starts up the desired service and passes theclient connection to it.The xinetd RPM package must be installed to use this superserver. If it is not, install it via Red Hat Network asdiscussed in Chapter 3, “Operating System Updates.”Configuring the xinetd ServerThe xinetd super daemon uses the /etc/xinetd.conf fileas the master configuration file and the /etc/xinetd.d/directory for configuration files per service controlled byxinetd. This section discusses how to use these files toconfigure xinetd and its services.