Changes
/* Linux */
Use <code>netstat -laputen | grep -i listen</code> to know which services are listening on which interface/port. If you activated the firewall, listening ports might not be reachable unless you configured your firewall to accept incoming connection to these services.
An alternative to the above use of ''netstat'' is <code>lsof -i -n</code> which shows open ports and open connections in a nice way.
You can use ''nmap'' from another computer to determine whether there still are open ports on your machine after the firewall is configured:
