Quick Tip: Use Apache as a proxy server to access internal IPs from an external machine

Sometimes, when you’re using a cloud server, you find yourself in a situation where you don’t have a GUI, but you still want to access a web server running on a local IP address. For example, if you install MCP using the Model Designer, what you get back will be an instance that includes DriveTrain running on a local IP address.  To solve this problem, we can use Apache as a proxy server to access that local IP address via an external IP address to that VM.

Obviously running an Apache proxy to another server isn’t something you will do lightly, and you may not do it at all for a production system; To use Apache as proxy on an unsecured server is inviting trouble, so make sure to do your security due diligence! But Just for testing, this can be a handy tip.

Fortunately it’s a straightforward process Here are the steps to use Apache as proxy:

1. Start by installing apache2. On Ubuntu, this is just a matter of calling the package manager:

   sudo apt-get install apache2

2. Enable the various modules needed to run an Apache proxy server. You can do that with the a2enmod tool:

   a2enmod proxy
   a2enmod proxy_http
   a2enmod proxy_ajp
   a2enmod rewrite
   a2enmod deflate
   a2enmod headers
   a2enmod proxy_balancer
   a2enmod proxy_connect
   a2enmod proxy_html

3. Access the Apache configuration  and add the following content to the /etc/apache2/sites-available/000-default.conf file to read:

   <VirtualHost *:*>
       ProxyPreserveHost On
   
       # Servers to proxy the connection, or;
       # List of application servers:
       # Usage:
       # ProxyPass / http://[IP Addr.]:[port]/
       # ProxyPassReverse / http://[IP Addr.]:[port]/
   
       # Example: 
       ProxyPass / http://10.10.0.15:8081/
       ProxyPassReverse / http://10.10.0.15:8081/
   
       ServerName localhost
   </VirtualHost>

   Obviously, make sure to use your own target URLs. Also, set the Apache proxy to port 80 (or whatever port you choose — in this case, 8081).

4. After configuring and setting the required parameters, restart the apache2 service to finally use Apache as proxy:

   service apache2 restart

At this point you can access the internal IP address (or whatever address you chose) from the main URL served by Apache. For more information, be sure to check Apache documentation online.