SlackBuildsOrg/network/redir
..
patches
README
redir.info
redir.SlackBuild
slack-desc

redir is all you need to redirect traffic across firewalls.
The functionality of inetd/tcpd and "redir" will allow you to
do everything you need without screwy telnet/ftp etc gateways.

Have a look at the man page or at /usr/doc/redir-*/README.md
for usage examples.