A firewall is a network security device that grants or rejects network access to traffic flows between an untrusted zone (e.g., the Internet) and trusted zone (e.g., a private or corporate network). The firewall acts as the demarcation point or “Immigration officials” in the network, as all communication should flow through it and it is where traffic is granted or rejected access. Firewalls enforce access controls through a positive control model, which states that only traffic defined in the firewall policy is allowed onto the network; all other traffic is denied.
Next-Generation Firewalls
Next-generation firewall (NGFWs) were created in response to the evolving sophistication of applications and malware. Application and malware developers have largely outwitted the long-standing port-based classification of traffic by building port evasion techniques into their programs. Today, malware piggybacks these application to enter network and became increasingly networked themselves (connected to each other on the computers they individually infected).
NGFWs act as a platform for network security policy enforcement and network traffic inspection. Per technology research firm Gartner Inc., They are defined by the following attributes:
• Standard capabilities of the first-generation firewall: This includes packet filtering, stateful protocol inspection, network-address translation (NAT), VPN connectivity, et cetera.
• Truly integrated intrusion prevention: this includes support for both vulnerability-facing and threat-facing signatures, and suggesting rules (or taking action) based on ISP activity. The sum of these two function collaborating via the NGFW is greater than the individual parts.
• Full stack visibility and application identification: ability to enforce policy at the application layer independently from port and protocol.
• Extrafirewall intelligence: ability to take information from external sources and make improved decisions. Examples include creation blacklists or whitelists and being able to map traffic to users and group using active directory.
• Adaptability to the modern threat landscape: Support upgrade paths for integration of new information feeds and new techniques to address future threats.
• In-line support: with minimum performance degradation or disruption to network operations.