Abstract: Techniques implemented by a network-access analysis system to analyze network access controls for networks, identify traffic flows that are unobserved and unrequired, and determine proposed changes to the network access controls that restrict access from unobserved traffic flows. The system may analyze the network access controls, and determine whether unrequired traffic flows are allowed to be communicated in the network. For instance, the system may analyze network flow logs and identify observed traffic flows that are required by applications in the network, and also identify unobserved traffic flows that are permitted access to, but are not observed in, the network. The system may propose changes to the network access controls to restrict network access by these unobserved traffic flows. A network administrator can receive recommendations from the system regarding the proposed changes, and determine whether they would like to implement the proposed changes to their network access controls.

Abstract: A network change verification (NCV) system is disclosed for checking whether a proposed configuration change on a network alters the way that the network controls recently observed network flows. In embodiments, the system builds an observed flow control model (OFCM) from logs of recent flows observed in the network. The OFCM, which may be periodically updated based on newly observed flows, provides a compact representation of how individual network flows were ostensibly controlled by the network. When a proposed configuration change is received, the system analyzes the change against the OFCM to check whether the change will alter how the network controls recently observed flows. If so, the proposed change is blocked, and an alert is generated identifying flows that are affected by the change. The NCV system thus prevents network operators from accidentally making changes on the network that will materially alter the behavior of the network.

Abstract: This disclosure describes techniques for identifying blocked paths and network configuration settings that block paths in networks, such as network paths in a virtual private cloud (VPC). The configuration of virtual networks depends on the correct configuration of many networking resources, such as firewalls, security groups, routing lists, access control lists (ACLs), and the like. In some cases, an analysis that uses formal methods can be performed to determine a network configuration of a virtual network. Using the network configuration information, network paths that are blocked and network configuration settings that may be blocking one or more of the network paths can be determined. The PAS can provide an explanation of what is blocking the network paths. For example, the PAS may identify that a configuration setting of a firewall, router, network gateway, an access control list (ACL), and the like may be blocking a network path.