What is a TCP wrapper and how do I use it? [closed]

Solution 1:

TCP Wrapper is a host-based Networking ACL system, used to filter network access to Internet. TCP wrappers was original written to monitor and stop cracking activities on the UNIX workstation in 90s. It was best solution in 90s to protect the UNIX workstations over the Internet. However it has few disadvantages:

1. All UNIX apps must be compiled with the libwrap library.
2. The wrappers do not work with RPC services over TCP.
3. The user name lookup feature of TCP Wrappers uses identd to identify the username of the remote host. By default, this feature is disabled, as identd may appear hung when there are large number of TCP connections.

However, it has one strong advantage over firewall. It works on the application layer. It can filter requests when encryption is used. Basically, you need to use both host based and network based security. Common services such as pop3, ftp, sshd, telnet, r-services are supported by TCP Wrappers.

^{Source:NIX CRAFT}