Should application remove the firewall rules on uninstall?

My product has a service which adds a firewall rule while starting (manual start) for the first time. Installer for my product does not add any firewall rule.

When I uninstall the product, as the service is not aware of whether the product is g开发者_开发知识库etting uninstalled, the firewall rule remains there on the box.

1) Is it fine to keep the firewall rule on the box? Will that harm the box in any way if the service adding that rule is not there?

2) Does windows firewall is aware of the application or just keeps the ports open for anyone even after the associated application is uninstalled?

Ideally Uninstall procedure should revert the system back to the pre install state as closely as possible. Hence as one of the best practices, you should delete the firewall rule.