Server-side client-certificate authorization

server.js

const express = require('express')
const fs = require('fs')
const https = require('https')

const opts = { key: fs.readFileSync('server_key.pem'), 
			   cert: fs.readFileSync('server_cert.pem'),
			   requestCert: true,
			   rejectUnauthorized: false,
			   ca: [ fs.readFileSync('server_cert.pem') ]
             }

const app = express();

app.get('/', (req, res) => {
	const cert = req.connection.getPeerCertificate()

	if (req.client.authorized) {
		res.json({ message: `Hello ${cert.subject.CN}, your certificate was issued by ${cert.issuer.CN}!`})

	} else if (cert.subject) {
		res.status(403)
		   .json({ message: `Sorry ${cert.subject.CN}, certificates from ${cert.issuer.CN} are not welcome here.`})
	} else {
		res.status(401)
		   .json({ message: `Sorry, but you need to provide a client certificate to continue.`})
	}
})

https.createServer(opts, app).listen(9999)