var Net = require('net')
  , NetKeepAlive = require('net-keepalive')
;

// Create a TCP Server
var srv = Net.createServer(function(s){
  console.log('Connected %j', s.address())
  // Doesn't matter what it does
  s.pipe(s)
});

// Start on some port
srv.listen(1337, function(){
  console.log('Listening on %j', srv.address())
});

// Connect to that server
var s = Net.createConnection({port:1337}, function(){
  console.log('Connected to %j', s.address())
  
  //IMPORTANT: KeepAlive must be enabled for this to work
  s.setKeepAlive(true, 1000)

  // Set TCP_KEEPINTVL for this specific socket
  NetKeepAlive.setKeepAliveInterval(s, 1000)
  
  // Get TCP_KEEPINTVL for this specific socket
  NetKeepAlive.getKeepAliveInterval(s) // 1000

  // Set TCP_KEEPCNT for this specific socket 
  NetKeepAlive.setKeepAliveProbes(s, 1)
  
  // Get TCP_KEEPCNT for this specific socket 
  NetKeepAlive.getKeepAliveProbes(s) // 1
});

var NetSocket = require('net-keepalive')

// .....
// get socket somehow
// .....

var enable = true                                           // enable SO_KEEPALIVE
var initialDuration = 1000                                  // start probing after 1 second of inactivity
socket.setKeepAlive(enable, initialDuration)                // sets SO_KEEPALIVE and TCP_KEEPIDLE

var probeInterval = 1000                                    // after initialDuration send probes every 1 second
NetSocket.setKeepAliveInterval(socket, probeInterval)       //sets TCP_KEEPINTVL

var maxProbesBeforeFail = 10                                // after 10 failed probes connection will be dropped 
NetSocket.setKeepAliveProbes(socket, maxProbesBeforeFail)   // sets TCP_KEEPCNT

// ....
// ....