simpleProxy  Is an easy to use tcp proxy server

    usage: simpleproxy -L <[srcHost:]srcPort> -R <destHost:destPort>

Network diagram

To connect to one of the computers in the test plant network running pcAnywhere do the following on the server running simpleProxy:
    $ simpleproxy -L 216.100.220.1:20035 -R 192.168.1.35:5631

For VNC:
    $ simpleproxy -L 216.100.220.1:5910 -R 192.168.1.10:5901
    Then connect with vncviewer towards 216.100.200.1:10

Please note that the used source host address and source port numbers are only examples.

Where to get the source:
simpleProxy@SourceForge

Debian package:
simpleproxy_3.1-3_i386.deb
Source