kaspersky anti virus keygen From my experience, hardware firewalls, at least the ones that are built into average NAT routers only really work against incoming threats. Threats that are already on your PC, such as viruses, trojans etc are generally able to get past a hardware firewall since its outgoing from your PC. The way I understood it in its simplest explanation is that average NAT router firewalls act more like a one-way valve in and out of your PC/LAN, which is why if you want incoming and outgoing protection most tend to use both a hardware and software firewall, the software providing the outgoing coverage.