How to apply TCP/IP based 2-way(publisher and subscriber) communication on an Ethernet port?

edit

I have a Nachi robot which uses CDF controller and I want to control it using ROS. I have a control algorithm on ROS which can control the robot in Gazebo, now I have to connect Nachi to ROS via an Ethernet cable and use TCP/IP for communication to control the robot.

In ROS I'm controlling the robot by a joystick so in short I want to control Nachi using a joystick.

Joystick <--(Working fine)--> ROS <--(TCP/IP on Ethernet port)--> CDF controller <--(Already set link)--Nachi.

So can anyone please refer me to some tutorial or just tell me in little detail what to do?

using ROS jade on ubuntu 14.04 Thanks in advance.