Fighting malware and spam

Firewall

Software (or hardware) used to block unwanted network traffic

Firewall software is designed to protect a system from network attacks, by blocking all ports not required for the system's operational purposes.

Firewalls can be run on the network edge, as software firewalls on servers or built in to hardware devices, or can be run at the client level, in which form they are often included in desktop security suites.