Denyallow

Denyallow refers to a technique of handling network access control by using two separate action lists - a deny list and an allow list. This approach is used in firewalls, web applications, and other network security measures to ensure that incoming traffic is thoroughly examined and restricted based on predetermined rules.

A deny list contains a list of IP addresses or local subnet masks that should be blocked from accessing the network. Conversely, the allow list contains those that are specifically allowed to access the system. This method is considered to be highly effective in minimizing the risk of network breaches, as incoming traffic must match both rules to be accepted.

Denyallow can be implemented using various security tools and appliances, such as firewalls, intrusion detection and prevention systems, and web application firewalls. In a typical configuration, incoming traffic is first checked against the deny list, and any packets that match a denied pattern are immediately rejected. This approach is highly beneficial as it prevents unauthorized access and can prevent malicious traffic from entering the network.

The denyallow method has been widely adopted and is often used in conjunction with other security protocols. While more complex and restrictive than simple allow lists, it is considered a robust security technique that requires careful planning and regular review of the lists to maintain its effectiveness.