How would you implement a simple TCP-level proxy or load balancer in Node.js using the net module, distinct from an HTTP-level reverse proxy?

The node:net module operates at the raw TCP level, below HTTP, letting you build a proxy that forwards raw byte streams between a client and a backend server without parsing or understanding HTTP semantics at all -- useful for protocols other than HTTP, or for a lightweight load-balancing layer that simply distributes TCP connections across backend servers without needing to inspect or modify the application-level protocol being carried over those connections.

const net = require('node:net');

const servers = [{ host: 'backend1', port: 4000 }, { host: 'backend2', port: 4000 }];
let current = 0;

net.createServer((clientSocket) => {
  const backend = servers[current++ % servers.length]; // simple round-robin
  const backendSocket = net.connect(backend, () => {
    clientSocket.pipe(backendSocket);
    backendSocket.pipe(clientSocket);
  });
}).listen(3000);