Tcp Wrappers; Xinetd - Red Hat ENTERPRISE LINUX 3 Reference Manual

Chapter 16.
TCP Wrappers and

xinetd

Controlling access to network services is one of the most important security tasks facing a server
administrator. Fortunately, under Red Hat Enterprise Linux there are a number of tools which do
just that. For instance, an -based firewall filters out unwelcome network packets within the
iptables
kernel's network stack. For network services that utilize it, TCP wrappers add an additional layer
of protection by defining which hosts are allowed or not allowed to connect to "wrapped" network
services. One such wrapped network service is the super server. This service is called a
xinetd
super server because it controls connections to a subset of network services and further refines access
control.
Figure 16-1 is a basic illustration of how these tools work together to protect network services.
Figure 16-1. Access Control to Network Services
This chapter focuses on the role of TCP wrappers and in controlling access to network ser-
xinetd
vices and reviews how these tools can be used to enhance both logging and utilization management.
For a discussion of firewalling with , refer to Chapter 17 .
iptables iptables