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To confirm that the setting is saved, you should see a line with the new firewall setting allowing in all traffic from the MIT 18.0.0.0 IPv4 range and the save button should be no longer click-able.
Now that we’ve allowed anyone from MIT to access the server it is time to deny access to everyone else.
1) At the bottom of the Control Panel -> Firewall window there should be a line that starts with “If no rules are matched”
2) Click on "Deny access”.
3) Again, remember to save. Fortunately if you attempt to navigate away or close the window without saving, it will let you know again that changes are not saved.
LAN 1 and LAN 2
If both of your ethernet ports are being used, you will need to apply these settings to both ethernet cards. On the tab level on the far right side you'll see a pull down menu. Select LAN 1 or LAN 2 to configure the appropriate ethernet port.