A host-based firewall is a piece of software installed and running on a single host that can restrict incoming (ingress) and outgoing (egress) network activity for that host only. The firewall software can prevent a host from getting infected by blocking access to the network port of potentially vulnerable services. This doesn't, however, prevent the compromise of a vulnerable service that isn't blocked by the firewall. Host-based firewalls have undergone many changes. They have gone from simple port-blocking utilities to application-aware firewalls that, much like network-based proxy-firewalls, can allow or deny network activity from a specific application installed on the host.
In addition to restricting network activity ...
