Many UNIX system administrators are accustomed to using TCP wrappers to
manage access to certain network services. Any network services managed
by xinetd (as well as any program with built-in support
for libwrap) can use TCP wrappers to manage access.
xinetd can use the
/etc/hosts.allow and
/etc/hosts.deny files to configure access to system
services. As the names imply, hosts.allow
contains a list of rules that allow clients to access the network services
controlled by xinetd, and
hosts.deny contains rules to deny
access. The hosts.allow file takes precedence over
the hosts.deny file. Permissions to grant or deny
access can be based on individual IP address (or hostnames) or on a
pattern of clients. See the Red Hat Linux Reference Guide and
hosts_access in section 5 of the man pages
(man 5 hosts_access) for details.
14.2.1. xinetd
To control access to Internet services, use xinetd,
which is a secure replacement for inetd. The
xinetd daemon conserves system resources, provides
access control and logging, and can be used to start special-purpose
servers. xinetd can be used to provide access
only to particular hosts, to deny access to particular hosts, to
provide access to a service at certain times, to limit the rate of
incoming connections and/or the load created by connections, and more
xinetd runs constantly and listens on all of the ports
for the services it manages. When a connection request arrives for one of
its managed services, xinetd starts up the appropriate
server for that service.
The configuration file for xinetd is
/etc/xinetd.conf, but
the file only contains a few defaults and an instruction to
include the /etc/xinetd.d directory. To enable or
disable an xinetd service, edit its configuration file
in the /etc/xinetd.d directory. If the
disable attribute is set to
yes, the service is disabled. If the
disable attribute is set to
no, the service is enabled.
You can edit any of the xinetd configuration files
or change its enabled status using the
Services Configuration Tool,
ntsysv, or chkconfig.
For a list of network services controlled by
xinetd, review the contents of the
/etc/xinetd.d directory with the command
ls /etc/xinetd.d.
