Node.js socket.setTTL() Method

The socket.setTTL() method is an inbuilt application programming interface of class Socket within dgram module which is used to set or clear the IP_TTL socket option which helps to specify how many IP hops that a packet is allowed to travel through the specified router or gateway.

Syntax:

const socket.setTTL( ttl )

Parameters: This method takes an integer value representing the number of IP hops that a packet is allowed to travel through the specified router or gateway.

Return Value: This method does not return any value.

Example 1: Filename: index.js

Javascript

// Node.js program to demonstrate the
// server.setTTL() method


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

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

// Catching 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_TTL socket option
        // and specifying the number of IP hopes
        // by using the setTTL() method
        server.setTTL(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.setTTL() method

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

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

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

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

    // Exiting process
    process.exit();
});

// Catching 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_TTL socket option
    // and specifying the number of IP hopes
    // by using the setTTL() method
    server.setTTL(144);
});

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

Output:

server listening 0.0.0.0:1234
UDP String: Hello

Run the index.js file using the following command:

node index.js

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