NATfirewalls

NATFirewalls are devices or software systems that combine network address translation with firewalling capabilities to manage traffic between an internal network and external networks. NAT translates private IP addresses to public addresses, typically using port address translation (PAT) to share a single public address among multiple internal hosts. A NAT firewall also performs stateful inspection, tracking active connections and allowing return traffic for legitimate sessions while blocking unsolicited inbound traffic.

Deployment and operation usually place NATFirewalls at the network edge, in home networks through consumer routers or in enterprise perimeters as dedicated appliances. They maintain a NAT table that records mappings between internal addresses and ports and external ones, and enforce access control rules. Common features include port forwarding, DMZ hosting, VPN passthrough, intrusion prevention, and logging for audit purposes.

Limitations and considerations include the fact that NATFirewalls do not guarantee complete security on their own and may not protect against all threats. Misconfigurations can expose networks, and NAT can complicate end-to-end connectivity, interfering with certain protocols, voice and video traffic, or some VPN implementations without proper settings or traversal techniques. They can also create performance bottlenecks if translation tables grow large or if packet inspection adds latency. Moreover, NAT changes can obscure peer addressing, requiring careful management of mappings and exposure rules.

Overall, NATFirewalls are a common component at the network edge, providing address translation and access control as part of a layered security approach, while recognizing their limitations and the need for complementary security measures.