[node.js] Get the client's IP address in socket.io

When using socket.IO in a Node.js server, is there an easy way to get the IP address of an incoming connection? I know you can get it from a standard HTTP connection, but socket.io is a bit of a different beast.

Version 0.7.7 of Socket.IO now claims to return the client's IP address. I've had success with:

var socket = io.listen(server);
socket.on('connection', function (client) {
  var ip_address = client.connection.remoteAddress;
}

If you use an other server as reverse proxy all of the mentioned fields will contain localhost. The easiest workaround is to add headers for ip/port in the proxy server.

Example for nginx: add this after your proxy_pass:

proxy_set_header  X-Real-IP $remote_addr;
proxy_set_header  X-Real-Port $remote_port;

This will make the headers available in the socket.io node server:

var ip = socket.handshake.headers["x-real-ip"];
var port = socket.handshake.headers["x-real-port"];

Note that the header is internally converted to lower case.

If you are connecting the node server directly to the client,

var ip = socket.conn.remoteAddress;

works with socket.io version 1.4.6 for me.

Latest version works with:

console.log(socket.handshake.address);

Very easy. First put

io.sockets.on('connection', function (socket) {

console.log(socket);

You will see all fields of socket. then use CTRL+F and search the word address. Finally, when you find the field remoteAddress use dots to filter data. in my case it is

console.log(socket.conn.remoteAddress);

In socket.io 2.0: you can use:

socket.conn.transport.socket._socket.remoteAddress

works with transports: ['websocket']

for 1.0.4:

io.sockets.on('connection', function (socket) {
  var socketId = socket.id;
  var clientIp = socket.request.connection.remoteAddress;

  console.log(clientIp);
});

This works for the 2.3.0 version:

io.on('connection', socket => {
   const ip = socket.handshake.headers['x-forwarded-for'] || socket.conn.remoteAddress.split(":")[3];
   console.log(ip);
});

In version v2.3.0

this work for me :

socket.handshake.headers['x-forwarded-for'].split(',')[0]

In 1.3.5 :

var clientIP = socket.handshake.headers.host;

Welcome in 2019, where typescript slowly takes over the world. Other answers are still perfectly valid. However, I just wanted to show you how you can set this up in a typed environment.

In case you haven't yet. You should first install some dependencies (i.e. from the commandline: npm install <dependency-goes-here> --save-dev)

  "devDependencies": {
    ...
    "@types/express": "^4.17.2",
    ...
    "@types/socket.io": "^2.1.4",
    "@types/socket.io-client": "^1.4.32",
    ...
    "ts-node": "^8.4.1",
    "typescript": "^3.6.4"
  }

I defined the imports using ES6 imports (which you should enable in your tsconfig.json file first.)

import * as SocketIO from "socket.io";
import * as http from "http";
import * as https from "https";
import * as express from "express";

Because I use typescript I have full typing now, on everything I do with these objects.

So, obviously, first you need a http server:

const handler = express();

const httpServer = (useHttps) ?
  https.createServer(serverOptions, handler) :
  http.createServer(handler);

I guess you already did all that. And you probably already added socket io to it:

const io = SocketIO(httpServer);
httpServer.listen(port, () => console.log("listening") );
io.on('connection', (socket) => onSocketIoConnection(socket));

Next, for the handling of new socket-io connections, you can put the SocketIO.Socket type on its parameter.

function onSocketIoConnection(socket: SocketIO.Socket) {      
  // I usually create a custom kind of session object here.
  // then I pass this session object to the onMessage and onDisconnect methods.

  socket.on('message', (msg) => onMessage(...));
  socket.once('disconnect', (reason) => onDisconnect(...));
}

And then finally, because we have full typing now, we can easily retrieve the ip from our socket, without guessing:

const ip = socket.conn.remoteAddress;
console.log(`client ip: ${ip}`);

From reading the socket.io source code it looks like the "listen" method takes arguments (server, options, fn) and if "server" is an instance of an HTTP/S server it will simply wrap it for you.

So you could presumably give it an empty server which listens for the 'connection' event and handles the socket remoteAddress; however, things might be very difficult if you need to associate that address with an actual socket.io Socket object.

var http = require('http')
  , io = require('socket.io');
io.listen(new http.Server().on('connection', function(sock) {
  console.log('Client connected from: ' + sock.remoteAddress);
}).listen(80));

Might be easier to submit a patch to socket.io wherein their own Socket object is extended with the remoteAddress property assigned at connection time...

For latest socket.io version use

socket.request.connection.remoteAddress

For example:

var socket = io.listen(server);
socket.on('connection', function (client) {
  var client_ip_address = socket.request.connection.remoteAddress;
}

beware that the code below returns the Server's IP, not the Client's IP

var address = socket.handshake.address;
console.log('New connection from ' + address.address + ':' + address.port);

I have found that within the socket.handshake.headers there is a forwarded for address which doesn't appear on my local machine. And I was able to get the remote address using:

socket.handshake.headers['x-forwarded-for']

This is in the server side and not client side.

on socket.io 1.3.4 you have the following possibilities.

socket.handshake.address,

socket.conn.remoteAddress or

socket.request.client._peername.address

Here's how to get your client's ip address (v 3.1.0):

// Current Client
const ip = socket.handshake.headers["x-forwarded-for"].split(",")[1].toString().substring(1, this.length);
// Server 
const ip2 = socket.handshake.headers["x-forwarded-for"].split(",")[0].toString();

And just to check if it works go to geoplugin.net/json.gsp?ip= just make sure to switch the ip in the link. After you have done that it should give you the accurate location of the client which means that it worked.

use socket.request.connection.remoteAddress

Using the latest 1.0.6 version of Socket.IO and have my app deployed on Heroku, I get the client IP and port using the headers into the socket handshake:

var socketio = require('socket.io').listen(server);

socketio.on('connection', function(socket) {

  var sHeaders = socket.handshake.headers;
  console.info('[%s:%s] CONNECT', sHeaders['x-forwarded-for'], sHeaders['x-forwarded-port']);

}

Since socket.io 1.1.0, I use :

io.on('connection', function (socket) {
  console.log('connection :', socket.request.connection._peername);
  // connection : { address: '192.168.1.86', family: 'IPv4', port: 52837 }
}

Edit : Note that this is not part of the official API, and therefore not guaranteed to work in future releases of socket.io.

Also see this relevant link : engine.io issue

This seems to work:

var io = require('socket.io').listen(80);
io.sockets.on('connection', function (socket) {
  var endpoint = socket.manager.handshaken[socket.id].address;
  console.log('Client connected from: ' + endpoint.address + ":" + endpoint.port);
});