Service redirection on other machine

xinetd can be used as a transparent proxy, It allows to send a service request towards an other machine to the desired port.

service telnet
{
flags = REUSE
socket_type = stream
wait = no
user = root
server = /usr/sbin/in.telnetd
only_from = 192.168.1.0/24
redirect = 192.168.1.15 23
}

Let's watch what's going on now:

>>telnet server
Trying 192.168.1.1...
Connected to server.
Escape character is '^]'.

Welcome to openSUSE 10.3 (i586)
Poison login:

At first, the connection seems to be established on server but the following shows that poison took over. This mecanism can be both useful and dangerous. When setting it up, logging must be done on both ends of the connection.