# Configure Reverse Proxy Using Nginx

The following is an example on how to set up a reverse proxy using `nginx` for DLS for your reference. You can do the configuration yourself as long as you can achieve the requirement which is to redirect requests sent to `https://www.yoursite.com/dls/*` to `http://127.0.0.1:48080/*`.

## Install nginx

### On CentOs

* Install

``` shell
rpm -ivh http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm 
yum install nginx
```

* Start

``` shell
systemctl start nginx.server
```

* Configure the web server to start with the OS

``` shell
systemctl enable nginx.server 
```

### On Ubuntu

``` shell
sudo apt install nginx-full
sudo systemctl start nginx
sudo systemctl enable nginx
```

## Test nginx

Open "http://localhost" in a browser. If `nginx` was installed and started successfully, you should see a message like

``` text
······ Welcome to nginx! ······ 
```

## Configure nginx

### Open the configuration file

The file could either be `/etc/nginx/conf.d/default.conf` or `/etc/nginx/sites-enabled/default` .

<!--
### Add your server name

``` shell
server_name www.yoursite.com;
```
-->

### Add reverse proxy

``` shell
location /dls/ {
  proxy_pass http://127.0.0.1:48080/;
}
```

### Restart the server

``` shell
sudo systemctl restart nginx
```

At this point, you can access the server with the URL `http://localhost/dls/page/index.html#/` or `http://<IP or www.yoursite.com>/dls/page/index.html#/`.

<!--At this point, you can access the server with the URL `http://www.yoursite.com/dls/page/index.html#/`.-->

## Configure SSL

For security, we should access DLS via HTTPS.

### Self-signed Certificate

For demoing and testing purposes, we can try the self-signed certificate when configuring `nginx` by uncommenting the 3 lines as shown below.

``` shell
server {
...
# SSL configuration
#
listen 443 ssl default_server;
listen [::]:443 ssl default_server;
#
# Note: You should disable gzip for SSL traffic.
# See: https://bugs.debian.org/773332
#
# Read up on ssl_ciphers to ensure a secure configuration.
# See: https://bugs.debian.org/765782
#
# Self signed certs generated by the ssl-cert package
# Don't use them in a production server!
#
include snippets/snakeoil.conf;
...
}
```

If your system doesn't have the self-signed certificate. You can install it like this

``` shell
sudo apt-get install ssl-cert
sudo make-ssl-cert generage-default-snakeoil
```

Your client needs to be configured to trust that self-signed certificate. For example, if you are running a web application, you can open the page `https://<IP or www.yoursite.com>/dls/page/index.html#/` in the browser and do the following

* Page shows warning about the self-signed certificate
* Click `Advanced`
* Click `Proceed to xxxx (unsafe)`.

Then this self-signed certificate will be trusted temporarily for some time.

> NOTE that you should avoid using self-signed certificates in your production server.

### Trusted Certificate

You can get a trusted certificate from many suppliers.

e.g. You can get a free one from [certbot](https://certbot.eff.org/).

> If you use a JavaScript-based SDK, such as Dynamic Web TWAIN WebAssembly Edition or Dynamsoft Barcode Reader JavaScript Edition, you must configure the self-hosted DLS to run over a secure connection (HTTPS).