Internet TCP redirection server

 rinetd redirects TCP connections from one IP address and port to another,
 with basic IP-based access control.
 .
 rinetd is a single-process server which handles any number of connections
 to the address/port pairs specified in the file /etc/rinetd.conf. Since
 rinetd runs as a single process using nonblocking I/O, it is able to
 redirect a large number of connections without a severe impact on the
 machine. This makes it practical to run services on machines inside an IP
 masquerading firewall.