Modify/etc/hosts. allow and/etc/hosts. deny allows linux servers to allow and restrict access to network services that can be started using xinetd programs, such as ftp telnet. We can modify/etc/hosts. allow and/etc/hosts. deny configuration to permit or deny access to IP addresses, hosts, and users. For example, we add all: 218.24.129 to/etc/hosts. allow. This will allow all customers from the 218.24.129. * domain to access it. This is just an example. In fact, by default, the system can use these network servers if we are in/etc/hosts. if deny is added, it is restricted from 218.24.129. * All IP addresses of the domain. All: 218.24.129. If we add all: 218.24.129.134 to/etc/hosts. deny, this restricts the access of all users in 218.24.129.134. When hosts. allow conflicts with host. deny, the hosts. allow settings are optimized. After setting, restart #/etc/rc. d/init. d/xinetd restart #/etc/rc. d/init. d/network restart does not allow any service program to use TCP_wrappers. For example, use the command ldd/usr/sbin/sshd. If libwrap is output, TCP_wrappers can be used, that is, the service can use/etc/hosts. allow and/etc/hosts. deny. It is unavailable if the output does not contain libwrap.