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NGINX reverse proxy with SSL cert authentication

NGINX reverse proxy with SSL cert authentication

This is a short guide for those who want to set up a NGINX reverse proxy with SSL cert authentication. The basic idea is to create a private CA and emit certificates signed by it. Only browsers and/or devices with the certs signed by this CA will be granted access to resources behind the proxy.

There are a few examples of similar configurations on the web, but most use openssl directly. This gist uses EasyRSA to simplify the task of creating and mantaining a private CA and certs to be distributed to clients.

Install and configure EasyRSA

Clone easyrsa v3:

$ cd
$ git clone

When git finishes, initialize your CA:

$ cd ~/easy-rsa/easyrsa3
$ ./easyrsa init-pki
$ ./easyrsa build-ca

Don't lose your CA password! Also, it's a good idea to maintain your CA keys in a machine outside your network. DO NOT store your CA keys on your server!

Easy-rsa will store your keys and certs under the ~/pki directory. Typical structure:

  • ~/pki/ca.crt <-- CA cert
  • ~/pki/issued <-- Issued client & server public certs
  • ~/pki/private <-- Issued keys & PKCS12 certs containing certs and keys.

NGINX server setup

In this example, we'll create a reverse proxy that acceps HTTPs requests on port 9999 and forwards them to port 8888 on the same machine where NGINX runs. Let's suppose your proxy runs on a server reachable from the outside on the "" name (change all instances of below for your real fqdn).

First, on the machine where easy-rsa was installed, create a server certificate:

$ cd ~/easy-rsa/easyrsa3
$ export HOST=""
$ ./easyrsa --alternate-san-name="DNS:${HOST}" build-server-full ${HOST} nopass

This will create a server certificate under ~/pki/issued and a server key under ~/pki/private.

Copy the following files from your easy-rsa machine into the "/etc/nginx/proxy" directory on your NGINX server. You may have to create the "/etc/nginx/certs" directory if it does not exist.

  • ~/pki/issued/
  • ~/pki/private/
  • ~/pki/ca.crt

Edit your NGINX config files. I prefer to not serve unqualified domains of any sort (all my valid configurations are vhosts.) Example of /etc/nginx/sites-enabled file below:

server {
  listen 80 default_server;
  listen 443 ssl default_server;
  listen [::]:80 default_server ipv6only=on;

  location = / {
    deny all;

  # Anything that does not match a vhost.
  server_name _;

  # SSL config
  ssl_certificate <path_to_your_letsencrypt_pem>;
  ssl_certificate_key <path_to_your_letsencrypt_key>;

In my case, my default serving configuration (for other resources under this site) uses letsencrypt certs. Adjust the configuration above as required for your case.

We now need a proxy config in a file called /etc/nginx/sites-enabled/

server {
  listen 9999 ssl;

  # SSL config
  # This uses self-signed certs to control access
  ssl_certificate      /etc/nginx/certs/;
  ssl_certificate_key  /etc/nginx/certs/;
  ssl_client_certificate /etc/nginx/certs/ca.crt;
  ssl_verify_client on;

  # Reverse proxy to port 8888
  location / {
    proxy_pass http://localhost:8888;

Restart nginx to pick up the changes and look for errors in the log files.

Client configuration

Generating client keys

We need to create a client cert. DO NOT share the same cert across multiple users/clients! At most, one cert per person (no sharing!). Let's say person is called "meh":

$ cd easy-rsa/easyrsa3
$ ./easyrsa --days=365 build-client-full meh-client nopass

This cert is valid for one year. Next, generate a PKCS#12 cert with this cert+key (most browsers can only load PKCS#12 certs):

$ ./easyrsa export-p12 meh-client

This will ask for a cert password. Type a non-obvious password and keep it safe. The browser will ask for this password at import time.

The ".p12" file will be saved under "~/pki/private".

Chrome installation

  • Copy the p12 file over to the client machine using a safe method (SSH).
  • Navigate to the Chrome Certificate Management page.
  • Click "Import" and selecte the p12 file. Type the pkcs#12 password as requested.
  • Still on the Cert management page, click on "Authorities".
  • Use Ctrl-F to locate "org-Easy-RSA ca".
  • Click on the line with the CA, select the "three dots" menu, then "Edit".
  • Select "Trust this certificate for identifying websites"

This should be all. To test, visit your site, port 9999.


(coming soon)


  • Copy the p12 file to your Android phone using a safe method (one option is to upload to your private Google Drive account - Android can install certs directly from Google Drive.)
  • Open the Android settings page.
  • Search for "Certificates" (the location of this changes a lot, depending on your Android version -- use the search function inside settings to locate).
  • Locate the "Install Certificates" page.
  • Select a new certificate (some versions of Android require the cert to be in local storage, others allow direct install from Google Drive.)
  • Give the certificate a name (say, "meh-client")
  • If asked, give choose "VPN and Apps" for the "Credential Use"
  • Install.

In my case, Android did not install the CA cert in a single operation. Repeat the steps above, but using the "ca.crt" file you created during the first step in your easyRSA installation.

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torrybr commented Sep 9, 2021

This line $ ./easyrsa export-p12 meh should be $ ./easyrsa export-p12 meh-client

Thank you for making this, nice work!

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marcopaganini commented Sep 10, 2021

This line $ ./easyrsa export-p12 meh should be $ ./easyrsa export-p12 meh-client

Thank you for making this, nice work!

Fixed. Thanks for the feedback!

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justinotherguy commented Apr 15, 2022

excellent write-up, thank you @marcopaganini !
I have added the configuration for iOS devices:
You might want to add that.

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