What ports should be open on a Ubuntu LAMP server?
If we're running Ubuntu Server with LAMP and Mail installed (that's all), what ports should be open for things to run smoothly. I know :80 is for Apache/HTTP, and one for MySql and SSH. What others should be kept open for the site and mail to work? We plan on keeping all others closed as most places will tell you. If there are others open is it something to be concerned? Also, what's the best way to find/list what ports are open and close them?