TCP Wrappers
TCP Wrappers ( also known as tcp_wrappers ) is a host-based networking ACL system , used to filter network access to Internet Protocol servers on ( Unix-like ) operating systems such as Linux or BSD . 
<triplet> TCP Wrappers <subj> Unix-like <obj> operating system <triplet> ACL <subj> operating system <obj> part of <triplet> filter <subj> operating system <obj> facet of <triplet> Unix-like <subj> operating system <obj> subclass of <triplet> Linux <subj> Unix-like <obj> implementation of