netwerkfirewalls

Netwerkfirewalls, or network firewalls, are security devices or software that monitor and control traffic between networks or network segments to implement policy and reduce risk. They serve as the first line of defense by enforcing rules that determine what traffic is allowed to pass from untrusted networks, such as the internet, to trusted networks, and vice versa.

Firewalls come in several architectures. Classic packet-filtering firewalls examine each packet’s header and allow or deny based on source, destination, port and protocol (stateless). Stateful inspection adds context by tracking active connections. Proxy firewalls act as intermediaries, terminating and re-initiating connections. Next-generation firewalls (NGFW) combine these approaches with application awareness, multi-path inspection, and integrated intrusion prevention systems (IPS), enabling more granular control over applications and protocols.

Common capabilities include network address translation (NAT), virtual private network (VPN) support (IPsec and TLS-based), and, in many cases, TLS interception for encrypted traffic. Policy management typically relies on rule sets that determine permit or deny decisions, with a principle of least privilege and a default deny rule. Logging, auditing, and integration with identity services support governance and incident response. High availability and centralized management are typical in enterprise deployments.

Deployment patterns include perimeter firewalls at the network edge, internal segmentation firewalls between security zones, DMZs that host public-facing services, and cloud or virtual firewalls protecting workloads in cloud environments.

Limitations include the challenge of inspecting encrypted traffic, potential performance impact, misconfiguration leading to gaps, and the need for ongoing maintenance. Trends include cloud-native and software-defined firewalls, zero-trust architectures, and improved automation and threat intelligence integration.