As computer security issues increase with the rising onslaught of computer crackers and viruses, operating systems (such as Red Hat Linux) are moving toward more security rather than more ease-of-use. Simply installing server software isn't enough to get the service up and running.
If a service isn't working, check the items listed below to hunt down the problem:
Is the software package(s) installed????Each network service is represented by one or more software packages. If you did a personal desktop or workstation install, most network server software may not be installed on your computer at all. Check Table C-1 to see which package(s) is needed for a service to work. (There may be other package dependencies as well, to which you will be alerted when you try to install the package.) Then use the rpm command to install the software from one of the installation CDs.
Does the firewall permit access to the service????The Red Hat Linux installation procedure lets you configure a firewall. If you choose the default (Medium security) firewall, most services will not be available outside your local computer. Refer to Chapter 14 for information on how to change your firewall configuration to open ports that provide the different services.
Is the start-up script set up to automatically launch the service????Most network services are launched from start-up scripts that cause daemon processes to continuously listen to the network for requests for the service. See the "Networking Service Daemons" section for information on how to find start-up scripts and have them launch automatically.
Is the configuration file created for the service????Even if the daemon process is listening for requests for a network service, one or more configuration files associated with the service must probably be set up before requests will be accepted. Table C-1 lists important configuration files for each type of server.
Does the configuration file permit proper access to the service????Within the configuration file for a service, there may be several levels of permissions that a user must go through to get permission to the service. For example, a configuration file may allow access to the service from a particular host computer, but deny access to a particular user.
Are there other restrictions to the service being shared????Some standard Linux security measures may block access to a service that is otherwise open to being shared. For example, you may share a Linux directory using NFS or FTP servers, but local file permissions may block access to the directory or files within the shared directory.
The rest of this appendix provides an overview of the daemon processes, start-up scripts, configuration files, and software packages that are associated with the networking services that come with Red Hat Linux.