What does it mean when a port is closed or in stealth?

System ports can be classified as:

Used - the port is used by the system or some application for incoming or outgoing connections.

Listen - the port is used by the system or some application to receive incoming messages.

Unused - the port is not used for any incoming or outgoing connections, the port is listed in the system.

Blocked/filtered - regardless of whether it is used or not, access to the port is forbidden according to Lavasoft Personal Firewall rules. Packets are dropped by the system and a 'port unreachable' ICMP message is sent to the packet source.

Allowed - regardless of whether it is used or not, access to the port is allowed according to Lavasoft Personal Firewall rules.

Unused ports can be put in stealth mode. A port in stealth means that packets sent to it are simply ignored by the firewall without notifying the source via any ICMP or TCP message. If a port is in listen or used, any invitation from an outside source to communicate is either accepted or a 'port unreachable' notification is sent, therefore that port is not and cannot be in stealth mode.

An open port is a port that is in listen and allowed by Lavasoft Personal Firewall. A closed port is a port that is blocked by Lavasoft Personal Firewall regardless of the port's state (whether it is in listen, used or unused states). Important: Know that netstat.exe and the Open Ports category in the Lavasoft Personal Firewall's left pane cannot be used for detecting whether a port is open or not. 'Listening' in terms of netstat simply means 'waiting for an inbound connection' regardless of whether it is allowed or blocked by Lavasoft Personal Firewall. Also note that information displayed in the Open Ports category in Lavasoft Personal Firewall's left pane lists those ports that are monitored by the firewall at the moment, but not all of them can actually be open on the network.