repl-client.js

var net = require('net')

var sock = net.connect(1337)

process.stdin.pipe(sock)
sock.pipe(process.stdout)

sock.on('connect', function () {
  process.stdin.resume();
  process.stdin.setRawMode(true)
})

sock.on('close', function done () {
  process.stdin.setRawMode(false)
  process.stdin.pause()
  sock.removeListener('close', done)
})

process.stdin.on('end', function () {
  sock.destroy()
  console.log()
})

process.stdin.on('data', function (b) {
  if (b.length === 1 && b[0] === 4) {
    process.stdin.emit('end')
  }
})

repl-server.js

var repl = require('repl')
var net = require('net')

net.createServer(function (socket) {
  var r = repl.start({
      prompt: 'socket '+socket.remoteAddress+':'+socket.remotePort+'> '
    , input: socket
    , output: socket
    , terminal: true
    , useGlobal: false
  })
  r.on('exit', function () {
    socket.end()
  })
  r.context.socket = socket
}).listen(1337)