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Node.js server.listen() Method

  • Last Updated : 15 Sep, 2020

The server.listen() is an inbuilt application programming interface of class Socket within tls module which is used to start the server to listen the encrypted connection.

Syntax:

const server.listen([port[, host[, backlog]]][, callback])

Parameters: This method takes the following argument as parameter:

  • port: It is the port number.

  • host: It’s the unspecified IPv4 address.



Return Value: This method has nothing to return but a callback function.

How to generate private key and public certificate?

  1. Private key: Open notepad and copy paste the following key:
    -----BEGIN RSA PRIVATE KEY-----
    MIICXQIBAAKBgQC38R9wXcUbhOd44FavgmE5R3K4JeYOHLnI7dUq1B8/Gv7l3SOg
    JKef/m9gM1KvUx951mapXGtcWgwB08J3vUE2YOZ4tWJArrVZES0BI/RmFAyhQFP5
    HcWl3LSM9LRihP98F33oIkKaCxA5LxOrkgpV4HrUzIKTABDYah7RPex1WQIDAQAB
    AoGBAIXR71xxa9gUfc5L7+TqBs+EMmrUb6Vusp8CoGXzQvRHMJCMrMFySV0131Nu
    o0YYRDsAh1nJefYLMNcXd1BjqI+qY8IeRsxaY+9CB2KKGVVDO2uLdurdC2ZdlWXT
    Vwr3dDoyR0trnXJMmH2ijTeO6bush8HuXxvxJBjvEllM5QYxAkEA3jwny9JP+RFu
    0rkqPBe/wi5pXpPl7PUtdNAGrh6S5958wUoR4f9bvwmTBv1nQzExKWu4EIp+7vjJ
    fBeRZhnBvQJBANPjjge8418PS9zAFyKlITq6cxmM4gOWeveQZwXVNvav0NH+OKdQ
    sZnnDiG26JWmnD/B8Audu97LcxjxcWI8Jc0CQEYA5PhLU229lA9EzI0JXhoozIBC
    TlcKFDuLm88VSmlHqDyqvF9YNOpEdc/p2rFLuZS2ndB4D+vu6mjwc5iZ3HECQCxy
    GBHRclQ3Ti9w76lpv+2kvI4IekRMZWDWnnWfwta+DGxwCgw2pfpleBZkWqdBepb5
    JFQbcxQJ0wvRYXo8qaUCQQCgTvWswBj6OTP7LTvBlU1teAN2Lnrk/N5AYHZIXW6m
    nUG9lYvH7DztWDTioXMrruPF7bdXfZOVJD8t0I4OUzvC
    -----END RSA PRIVATE KEY-----

    Save file as private-key.pem

  2. Public certificate: Open notepad and copy paste the following key:
    -----BEGIN CERTIFICATE-----
    MIICfzCCAegCCQDxxeXw914Y2DANBgkqhkiG9w0BAQsFADCBgzELMAkGA1UEBhMC
    SU4xEzARBgNVBAgMCldlc3RiZW5nYWwxEDAOBgNVBAcMB0tvbGthdGExFDASBgNV
    BAoMC1BhbmNvLCBJbmMuMRUwEwYDVQQDDAxSb2hpdCBQcmFzYWQxIDAeBgkqhkiG
    9w0BCQEWEXJvZm9mb2ZAZ21haWwuY29tMB4XDTIwMDkwOTA1NTExN1oXDTIwMTAw
    OTA1NTExN1owgYMxCzAJBgNVBAYTAklOMRMwEQYDVQQIDApXZXN0YmVuZ2FsMRAw
    DgYDVQQHDAdLb2xrYXRhMRQwEgYDVQQKDAtQYW5jbywgSW5jLjEVMBMGA1UEAwwM
    Um9oaXQgUHJhc2FkMSAwHgYJKoZIhvcNAQkBFhFyb2ZvZm9mQGdtYWlsLmNvbTCB
    nzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAt/EfcF3FG4TneOBWr4JhOUdyuCXm
    Dhy5yO3VKtQfPxr+5d0joCSnn/5vYDNSr1MfedZmqVxrXFoMAdPCd71BNmDmeLVi
    QK61WREtASP0ZhQMoUBT+R3Fpdy0jPS0YoT/fBd96CJCmgsQOS8Tq5IKVeB61MyC
    kwAQ2Goe0T3sdVkCAwEAATANBgkqhkiG9w0BAQsFAAOBgQATe6ixdAjoV7BSHgRX
    bXM2+IZLq8kq3s7ck0EZrRVhsivutcaZwDXRCCinB+OlPedbzXwNZGvVX0nwPYHG
    BfiXwdiuZeVJ88ni6Fm6RhoPtu2QF1UExfBvSXuMBgR+evp+e3QadNpGx6Ppl1aC
    hWF6W2H9+MAlU7yvtmCQQuZmfQ==
    -----END CERTIFICATE-----

    Save file as public-cert.pem

Example 1: Filename: index.js




// Node.js program to demonstrate the
// server.listen() method
  
var tls = require('tls'),
    fs = require('fs'),
  
// Port and host address for server    
PORT = 1337,
HOST = '127.0.0.1';
   
// Private key and public certificate for access
var options = {
  key: fs.readFileSync('private-key.pem'),
  cert: fs.readFileSync('public-cert.pem'),
  rejectUnauthorized: false
};
  
// Creating and initializing server
var server = tls.createServer(options, function(socket) {
  
  // Print the data that we received
  socket.on('data', function(data) {
     console.log('\nReceived: %s ',
     data.toString().replace(/(\n)/gm, ""));
  });
  
  // Stopping the server
  // by using the close() method
  server.close();
});
  
// Getting session key 
// by using getTicketKeys() method
const value1 = server.getTicketKeys();
console.log(value1)
  
// Close event
server.on('close', () => {
  console.log("Server closed successfully");
})
  
// Start listening on a specific port and address
// by using listen() method
server.listen(PORT, HOST, function() {
  console.log("I'm listening at %s, on port %s", HOST, PORT);
});
  
// Creating and initializing client
var client = tls.connect(PORT, HOST, options, function() {
    
  // Getting the bound address 
  // by using address method
  const value = client.address();
  client.write("Bound address : " + value)
  client.end();
});

Output:

<Buffer 72 59 e4 89 85 0f ae fb eb e6 cb 3a 1a bf 92 19 2f ab 97 be 5d 10 19 50 cc 0f 98 d3 27 fe 9c 68 2a 31 f3 e8 17 b7 77 38 88 f0 28 64 90 1c 36 40>
I’m listening at 127.0.0.1, on port 1337

Received: Bound address : [object Object]
Server closed successfully

Example 2: Filename: index.js




// Node.js program to demonstrate the
// server.listen() method
  
var tls = require('tls'),
    fs = require('fs'),
  
// Port and host address for server    
PORT = 1337,
HOST = '127.0.0.1',
value = null;
   
// Private key and public certificate for access
var options = {
  key: fs.readFileSync('private-key.pem'),
  cert: fs.readFileSync('public-cert.pem'),
  rejectUnauthorized: false
};
  
// Creating and initializing server
var server = tls.createServer(options, function(socket) {
  
  // Print the data that we received
  socket.on('data', function(data) {
    console.log('\nReceived: %s ',
    data.toString());
  });
  
  // Stopping the server
  // by using the close() method
  server.close();
});
  
// Getting session key 
// by using getTicketKeys() method
value = server.getTicketKeys();
  
// Start listening on a specific port and address
// by using listen() method
server.listen(PORT, HOST, function() {
  console.log("I'm listening at %s, on port %s", HOST, PORT);
});
  
// Creating and initializing client
var client = tls.connect(PORT, HOST, options, function() {
  client.write("Session key : " + value[0])
  client.end();
});

Run the index.js file using the following command:

node index.js

Output:

I'm listening at 127.0.0.1, on port 1337

Received: Session key : 106

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




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