AL-SAFE: A Secure Self-Adaptable Application-Level Firewall for IaaS Clouds

Application-level firewalls filter traffic based on a white list of processes that are allowed to access the network. Although they have a complete overview of the system in which they are executed, they can be easily bypassed by knowledgable attackers. In this paper we present AL-SAFE, a cloud-tailored application-level self-adaptable firewall which combines the high degree of visibility of an application-level firewall with the isolation of a traditional standalone firewall. AL-SAFE is able to filter traffic at two distinct points in the virtual infrastructure and adapt the enforced rulesets based on changes in the virtual infrastructure topology and the list of services running inside the virtual machines. Our performance analysis shows that AL-SAFE imposes a tolerable delay to legitimate network connections while it is able to filter out all unauthorised packets.