Express.js – Getting Remote Client Address

An application needs to maintain the remote client address for managing the number of requests from a computer system and tracking its usage. But sometimes, the server runs behind an NGINX server, so we need to check its forward request. For this purpose, we can use "x-forwarded-for"

Syntax

req.headers['x-forwarded-for'] || req.socket.remoteAddress

If the proxy isn't yours, one should be careful while using the x-forwarded-for header, because it can be spoofed.

Example 1

Create a file with the name "remoteAddress.js" and copy the following code snippet. After creating the file, use the command "node remoteAddress.js" to run this code as shown in the example below −

// req.query() Demo Example

// Importing the express module
var express = require('express');

// Initializing the express and port number
var app = express();
var PORT = 3000;

// Getting the request query string
app.get('/api', function(req, res){
   console.log('id: ' + req.query.id)
   res.send('id: ' + req.query.id);
});

// Listening to the port
app.listen(PORT, function(err){
   if (err) console.log(err);
   console.log("Server listening on PORT", PORT);
});

Hit a Get Request at the following endpoint - http://localhost:3000/

Output

C:\home
ode>> node remoteAddress.js
Server listening on PORT 3000
IP Address: ::ffff:127.0.0.1

Example 2

Let's take a look at one more example.

// express.raw() Demo Example

// Importing the express module
var express = require('express');

// Initializing the express and port number
var app = express();
var PORT = 3000;

app.get('/api*', function (req, res){
   var ip = req.headers['x-forwarded-for'] || req.socket.remoteAddress
   console.log('IP Address: ' + ip)
});

// Listening to the port
app.listen(PORT, function(err){
   if (err) console.log(err);
   console.log("Server listening on PORT", PORT);
});

app.get('/', function (req, res){
   var forwardedIpsStr = req.header('x-forwarded-for');
   var IP = '';

   if (forwardedIpsStr) {
      IP = forwardedIps = forwardedIpsStr.split(',')[0];
   }
});

Hit a Get Request for any of the following endpoints –

http://localhost:3000/api
http://localhost:3000/api/v2
http://localhost:3000/api/v3 and so on...

It will compare all the endpoints with /api and track it.

Output

C:\home
ode>> node remoteAddress.js
Server listening on PORT 3000
IP Address: ::ffff:127.0.0.1
IP Address: ::ffff:127.0.0.1
IP Address: ::ffff:127.0.0.1