Node.js socket.setMulticastTTL() Method

The socket.setMulticastTTL() is an inbuilt application programming interface of class Socket within dgram module which is used to set or clear the IP_MULTICAST_TTL socket option which helps to specify how many number of IP hops that a packet is allowed to travel through the specified multicast traffic.

Syntax:

const socket.setMulticastTTL( ttl )

Parameters: This method takes integer value representing the number of IP hops that a packet is allowed to travel through the specified multicast traffic.

Return Value: This method does not return any value.

Example 1: Filename: index.js

javascript

// Node.js program to demonstrate the
// server.setMulticastTTL()  API

// Importing dgram module
var dgram = require('dgram');

// Creating and initializing client
// and server socket
var client = dgram.createSocket("udp4");
var server = dgram.createSocket("udp4");
let broadcast_address = 12345;

// Handling the message event
server.on("message", function (msg) {

   // Displaying the client message
   process.stdout.write("UDP String: "
                      + msg + "\n");

   // Exiting process
   process.exit();
})
.bind(broadcast_address, () => {
  // Enable the IP_MULTICAST_TTL socket option
  // and specifying the number of IP hopes
  // by using the setMulticastTTL() method
  server.setMulticastTTL(144);
});

// Client sending message to server
client.send("Hello", 0, 7,
    broadcast_address, "localhost");

Output:

UDP String: Hello

Example 2: Filename: index.js

javascript

// Node.js program to demonstrate the
// server.setMulticastTTL()  API

// Importing dgram module
var dgram = require('dgram');

// Creating and initializing client
// and server socket
var client = dgram.createSocket("udp4");
var server = dgram.createSocket("udp4");

// Handling the message event
server.on("message", function (msg) {

  // Displaying the client message
  process.stdout.write("UDP String: "
                       + msg + "\n");

  // Exiting process
  process.exit();

});

// Handling the listening event
server.on('listening', () => {
  const address = server.address();
  console.log(`server listening
    ${address.address}:${address.port}`);
});

// Binding server with port address
server.bind(1234, () => {

   // Enable the IP_MULTICAST_TTL socket option
   // and specifying the number of IP hopes
   // by using the setMulticastTTL() method
   server.setMulticastTTL(255);
});

// Client sending message to server
client.send("Hello", 0, 7,
    1234, "localhost");

Run the index.js file using the following command:

node index.js

Output:

server listening 0.0.0.0:1234
UDP String: Hello

Reference: https://nodejs.org/dist/latest-v12.x/docs/api/dgram.html#dgram_socket_setmulticastttl_ttl