This works similar to the WebTool Access Control section except these rules apply system-wide.
Entering an IP address in the given IP Address field will allow that IP Address to connect to EnGarde using the selected service. Checking the 'Allow all addresses' check-box will allow any and all IP Address to access the selected service. Examples are given above the IP Address field.
Once you have that typed in click the Add Host button and your new settings will appear below once the screen refreshes.