# NGINX Reverse Proxy
These are the steps required to use NGINX (opens new window), a lightweight HTTP server, although you can use Apache server or any other HTTP server which supports reverse proxying.
# Installation
NGINX runs as a service in most Linux distributions, installation should be as simple as:
sudo apt-get update && sudo apt-get install nginx
Once installed, you can test to see if the service is running correctly by going to http://mydomain_or_myip, you should see the default "Welcome to nginx" page.
If you don't, you may need to check your firewall or ports and check if port 80 (and 443 for HTTPS later) is not blocked and that services can use it.
# Basic Configuration
NGINX configures the server when it starts up based on configuration files.
The location of the default setup is /etc/nginx/sites-enabled/default. To allow NGINX to proxy openHAB, you need to change this file (make a backup of it in a different folder first).
The recommended configuration below assumes that you run the reverse proxy on the same machine as your openHAB runtime.
If this doesn't fit for you, you just have to replace proxy_pass http://localhost:8080/ by your openHAB runtime hostname (such as http://youropenhabhostname:8080/).
server {
listen 80;
server_name mydomain_or_myip;
# Cross-Origin Resource Sharing
add_header 'Access-Control-Allow-Origin' '*' always;
add_header 'Access-Control-Allow_Credentials' 'true' always;
add_header 'Access-Control-Allow-Headers' 'Authorization,Accept,Origin,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range' always;
add_header 'Access-Control-Allow-Methods' 'GET,POST,OPTIONS,PUT,DELETE,PATCH' always;
location / {
proxy_http_version 1.1;
proxy_pass http://localhost:8080/;
proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_read_timeout 3600;
}
}
It is also recommended to name the file to something relevant to what it's doing, if you already have a default file in place, then you can rename it via:
sudo mv /etc/nginx/sites-enabled/default /etc/nginx/sites-enabled/openhab
Otherwise, create a new file. Every file in the sites-enabled folder gets processed by NGINX, so make sure you only have one per site.
After saving over the file but before you commit the changes to our server, you should test to see if our changes contain any errors; this is done with the command:
sudo nginx -t
If you see that the test is successful, you can restart the NGINX service with...
sudo service nginx restart
...and then go to http://mydomain_or_myip to see your openHAB server.
# Authentication
For further security, you may wish to ask for a username and password before users have access to openHAB. This is fairly simple in NGINX once you have the reverse proxy setup, you just need to provide the server with a basic authentication user file.
# Adding or Removing users
You will be using htpasswd to generate a username/password file, this utility can be found in the apache2-utils package:
sudo apt-get install apache2-utils
To add users to your reverse proxy, you must use following command. Use the -c modifier only for your first user. It will create a new password file. Do not use the -c modifier again as this will remove all previously created users. Don't forget to change username to something meaningful!
sudo htpasswd -c /etc/nginx/.htpasswd username
sudo htpasswd /etc/nginx/.htpasswd username
and to delete an existing user:
sudo htpasswd -D /etc/nginx/.htpasswd username
Once again, any changes you make to these files must be followed with restarting the NGINX service otherwise no changes will be made.
# Referencing the File in the NGINX Configuration
Now the configuration file (/etc/nginx/sites-enabled/openhab) needs to be edited to use this password.
Open the configuration file and add the following lines underneath the proxy_* settings:
auth_basic "Username and Password Required";
auth_basic_user_file /etc/nginx/.htpasswd;
# Add authorization and cookie directives in NGINX Configuration
This is an important new requirement in openHAB 3.0 and later versions.
This is not required prior to openHAB 3.0. You must add the following two directives underneath the add_header (in the server block) and proxy_set_header (in the location / block) items respectively:
add_header Set-Cookie X-OPENHAB-AUTH-HEADER=1;
proxy_set_header Authorization "";
Once done, test and restart your NGINX service and authentication should now be enabled on your server!
# Use a client certificate based authentication
You can find a short tutorial in the community forum on how to do so. Using NGINX Reverse Proxy for client certificate authentication (opens new window)
# Making Exceptions for Specific IP addresses
It is often desirable to allow specific IPs (e.g. the local network) to access openHAB without needing to prompt for a password or to block everyone else entirely.
In these cases NGINX can use the satisfy any directive followed by allow and deny lines to make these exceptions.
These lines are placed in the location{} block. For example, by adding the lines:
satisfy any;
allow 192.168.0.0/24;
allow 127.0.0.1;
deny all;
NGINX will allow anyone within the 192.168.0.0/24 range and the localhost to connect without a password. If you have setup a password following the previous section, then the rest will be prompted for a password for access.
# Setting up a Domain
To generate a trusted certificate, you need to own a domain. To acquire your own domain, you can use one of the following methods:
| Method | Example Links | Note |
|---|---|---|
| Purchasing a domain name | GoDaddy (opens new window), Namecheap (opens new window), Enom (opens new window), Register (opens new window) | You should have an IP address that doesn't change (i.e. fixed), or changes rarely, and then update the DNS A record so that your domain/subdomain to point towards your IP. |
| Obtaining a free domain | FreeNom (opens new window) | Setup is the same as above. |
| Using a "Dynamic DNS" service | No-IP (opens new window), Dyn (opens new window), FreeDNS (opens new window) | Uses a client to automatically update your IP to a domain of you choice, some Dynamic DNS services (like FreeDNS) offer a free domain too. |
# Enabling HTTPS
Encrypting the communication between client and the server is important because it protects against eavesdropping and possible forgery. The following options are available depending if you have a valid domain:
If you have a valid domain and can change the DNS to point towards your IP, follow the instructions for Let's Encrypt. If you need to use an internal or external IP to connect to openHAB, follow the instructions for OpenSSL.
# Using OpenSSL to Generate Self-Signed Certificates
OpenSSL is also packaged for most Linux distributions, installing it should be as simple as:
sudo apt-get install openssl
Once complete, you need to create a directory where our certificates can be placed:
sudo mkdir -p /etc/ssl/certs
Now OpenSSL can be told to generate a 2048 bit long RSA key and a certificate that is valid for a year:
sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/ssl/openhab.key -out /etc/ssl/openhab.crt
You will be prompted for some information which you will need to fill out for the certificate, when it asks for a Common Name, you may enter your IP Address: Common Name (e.g. server FQDN or YOUR name) []: xx.xx.xx.xx
# Using Let's Encrypt to Generate Trusted Certificates
TIP
Skip this step if you have no domain name or have already followed the instructions for OpenSSL
Let's Encrypt is a service that allows anyone with a valid domain to automatically generate a trusted certificate, these certificates are usually accepted by a browser without any warnings.
# Setting up the NGINX Proxy Server to Handle the Certificate Generation Procedure
Let's Encrypt needs to validate that the server has control of the domain. The simplest way of doing this is using a webroot plugin to place a file on the server, and then access it using a specific url: /.well-known/acme-challenge. Since the proxy only forwards traffic to the openHAB server, the server needs to be told to handle requests at this address differently.
First, create a directory that Certbot can be given access to:
sudo mkdir -p /var/www/mydomain
Next add the new location parameter to your NGINX config, this should be placed above the last brace in the server setting:
location /.well-known/acme-challenge/ {
root /var/www/mydomain;
}
# Using Certbot
Certbot is a tool which simplifies the process of obtaining secure certificates. The tool may not be packaged for some Linux distributions so installation instructions may vary, check out their website (opens new window) and follow the instructions using the webroot mode. Don't forget to change the example domain to your own! An example of a valid certbot command (in this case for Debian Jessie) would be:
sudo certbot certonly --webroot -w /var/www/mydomain -d mydomain
# Adding the Certificates to Your Proxy Server
If you followed one of the two guides for OpenSSL or Let's Encrypt above, the certificate and key should have been placed in /etc/letsencrypt/live/mydomain_or_myip/ or /etc/ssl/ respectively.
NGINX needs to be told where these files are and then enable the reverse proxy to direct HTTPS traffic, using Strict Transport Security to prevent man-in-the-middle attacks.
In the NGINX configuration, place one of the following underneath your server_name variable:
ssl_certificate /etc/ssl/openhab.crt;
ssl_certificate_key /etc/ssl/openhab.key;
ssl_certificate /etc/letsencrypt/live/mydomain_or_myip/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/mydomain_or_myip/privkey.pem;
add_header Strict-Transport-Security "max-age=31536000";
# Setting Your NGINX Server to Listen to the HTTPS Port
Regardless of the option you choose, make sure you change the port to listen in on HTTPS traffic.
listen 443 ssl;
After restarting NGINX service, you will be using a valid HTTPS certificate.
You can check by going to https://mydomain_or_myip and confirming with your browser that you have a valid certificate.
Let's Encrypt certificates expire within a few months so it is important to run the updater in a cron expression (and also restart NGINX) as explained in the Certbot setup instructions.
If you want to keep hold of a HTTP server for some reason, just add listen 80; and remove the Strict-Transport-Security line.
# Redirecting HTTP Traffic to HTTPS
You may want to redirect all HTTP traffic to HTTPS, you can do this by adding the following to the NGINX configuration. This will essentially replace the HTTP url with the HTTPS version!
server {
listen 80;
server_name mydomain_or_myip;
return 301 https://$server_name$request_uri;
}
It might be the case that you can't use standard ports. When trying to access a HTTPS port with HTTP, NGINX will respond with a 400 Bad Request.
We can redirect this gracefully using a "HTTPS error page (opens new window)" for the non-standard HTTP error code 497 (opens new window)
server {
listen 8084 ssl;
server_name mydomain_or_myip;
error_page 497 =301 https://$host:$server_port$request_uri;
}
# Putting it All Together
After following all the steps on this page, you should have a NGINX server configuration (/etc/nginx/sites-enabled/openhab) that looks like this:
server {
listen 80;
server_name mydomain_or_myip;
return 301 https://$server_name$request_uri;
}
server {
listen 443 ssl;
server_name mydomain_or_myip;
# Cross-Origin Resource Sharing.
add_header 'Access-Control-Allow-Origin' '*' always;
add_header 'Access-Control-Allow_Credentials' 'true' always;
add_header 'Access-Control-Allow-Headers' 'Authorization,Accept,Origin,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range' always;
add_header 'Access-Control-Allow-Methods' 'GET,POST,OPTIONS,PUT,DELETE,PATCH' always;
# openHAB 3 api authentication
add_header Set-Cookie X-OPENHAB-AUTH-HEADER=1;
ssl_certificate /etc/letsencrypt/live/mydomain/fullchain.pem; # or /etc/ssl/openhab.crt
ssl_certificate_key /etc/letsencrypt/live/mydomain/privkey.pem; # or /etc/ssl/openhab.key
add_header Strict-Transport-Security "max-age=31536000"; # Remove if using self-signed and are having trouble.
location / {
proxy_http_version 1.1;
proxy_pass http://localhost:8080/;
proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "Upgrade";
proxy_set_header Authorization "";
satisfy any;
allow 192.168.0.0/24;
allow 127.0.0.1;
deny all;
auth_basic "Username and Password Required";
auth_basic_user_file /etc/nginx/.htpasswd;
}
#### When using Let's Encrypt Only ####
location /.well-known/acme-challenge/ {
root /var/www/mydomain;
}
}
# Additional HTTPS Security
To test your security settings SSL Labs (opens new window) provides a tool for testing your domain against ideal settings (Make sure you check "Do not show the results on the boards" if you don't want your domain seen).
This optional section is for those who would like to strengthen the HTTPS security on openHAB, it can be applied regardless of which HTTPS method you used above, but you need to follow at least one of them first.
First, we need to generate a stronger key exchange, to do this we can generate an additional key with OpenSSL.
Note
Depending on your hardware this will take up to few minutes to complete:
mkdir -p /etc/nginx/ssl
openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
Now we can configure NGINX to use this key, as well as telling the client to use specific cyphers and SSL settings, just add the following under your ssl_certificate ** settings but above location *.
All of these settings are customizable, but make sure you read up on (opens new window) what these do first before changing them:
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_prefer_server_ciphers on;
ssl_dhparam /etc/nginx/ssl/dhparam.pem;
ssl_ciphers ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:HIGH:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!CBC:!EDH:!kEDH:!PSK:!SRP:!kECDH;
ssl_session_timeout 1d;
ssl_session_cache shared:SSL:10m;
keepalive_timeout 70;
Feel free to test the new configuration again on SSL Labs (opens new window). If you're achieving A or A+ here, then your client-openHAB communication is very secure.
# Further Reading
The setup above is a suggestion for high compatibility with an A+ rating at the time of writing, however flaws in these settings (particularly the cyphers) may become known overtime. The following articles may be useful when understanding and changing these settings.
- Better Crypto (opens new window)
- SSL Labs - Best Practices (opens new window)
- Hynek Schlawack - Hardening Your Web Server’s SSL Ciphers (opens new window)