Configuring a Firewall or Proxy Server

A firewall is a system designed to keep everything behind it safe from the outside world. It scans incoming connections and determines whether or not the connection matches one of a list of pre-defined access control rule, accepts or rejecting the connection.

If your EnGarde system will be positioned behind firewall you will need to configure your firewall to allow EnGarde access to the outside world. Below are a list of ports and what they are. You may not have all of the listed ports opened on your EnGarde system if you don't have it configured to. For example, if your EnGarde system is not a DNS server you will not have the DNS port 53 opened.

• [22/tcp]This is the SSH port. If you want to allow anyone from outside to SSH into your machine you must open this port
• [25/tcp]This is the SMTP service. If this machine will be receiving e-mail this port must be available.
• [53/tcp&udp]This is the DNS service. You will need to have this opened. Configuring DNS to work through a firewall or proxy server can be difficult and it is recommended to refer to your firewall manual for complete instructions.
• [80/tcp]If EnGarde is going to be a Web server you will need to enable access to this port.
• [443/tcp]If EnGarde is a Web server and will be hosting a secure site you will need to open this port to support SSL
• [993/tcp]If EnGarde will be offering Secure IMAP you will need to have this port open.
• [995/tcp]Secure POP3 will be available from this port if EnGarde is running it.
• [1022/tcp]This is the user password changer portion of the GD WebTool. If you want to give outside users to availability to change their own password via the GD WebTool you will need to open this port up.
• [1023/tcp]This is the actual GD WebTool for the administrator. If you will be administrating this from outside you will need to open the port.

For more information about firewalls there are many books and on-line documentation. Refer to your firewall documentation for specific instructions on how to permit these services through your firewall. Additionally, here are a few references:

• Zwicky, Cooper & Chapman. Building Internet Firewalls, June 2000. Copyright O'Reilly & Associates, Inc. 2007.
• Mark Grennan, mark@grennan.com. Firewall and Proxy Server HOWTO, Feb. 26, 2000. Copyright Mark Grennan, 2007.