Zone Defense Tools
Use a layered approach with multiple levels of protection to defend your network against DoS attacks.
Effective defense against DoS attacks requires a layered approach. The first layer of defense should be a dedicated, high-volume DDoS protection device at the internet-facing network perimeter and a perimeter router, switch, or other hardware-based packet drop device with appropriate access control lists (ACLs) to defend against volumetric attacks that the session-based firewall isn’t designed to handle. The firewall adds more granular layers of DoS attack defense and also visibility into application traffic that dedicated DDoS devices don’t provide.
Palo Alto Networks firewalls provide four complementary tools to layer in DoS protection for your network zones and critical devices:
- Zone protection profiles defend the network as a session is formed, before the firewall performs DoS Protection policy and Security policy rule lookups, and consume fewer CPU cycles than a DoS Protection policy or Security policy rule lookup. If a Zone Protection profile denies traffic, the firewall doesn’t spend CPU cycles on policy rule lookups.Apply Zone Protection profiles to every zone, both internet-facing and internal.
- Because the intent of DoS protection is to defend critical devices and because it consumes resources, DoS protection defends only the devices you specify in a DoS Protection policy rule. No other devices are protected.DoS Protection profiles set flood protection thresholds (new CPS limits) for individual devices or groups of devices, resource protection thresholds (session limits for specified endpoints and resources), and whether the profile applies to aggregate or classified traffic. DoS Protection policy rules specify match criteria (source, destination, service ports), the action to take when traffic matches the rule, and the aggregate and classified DoS Protection profiles associated with each rule.AggregateDoS Protection policy rules apply the CPS thresholds defined in an aggregate DoS Protection profile to the combined traffic of all the devices that meet the DoS Protection policy rule match criteria. For example, if you configure the aggregate DoS Protection profile to limit the CPS rate to 20,000, the 20,000 CPS limit applies to the aggregate number of connections for the entire group. In this case, one device could receive the majority of the allowed connections.ClassifiedDoS Protection policy rules apply the CPS thresholds defined in a classified DoS Protection profile to each individual device that matches the policy rule. For example, if you configure the classified DoS Protection profile to limit the CPS rate to 4,000, then no device in the group can accept more than 4,000 CPS. A DoS Protection policy can have one aggregate profile and one classified profile.Classified profiles can classify connections by source IP, destination IP, or both. For internet-facing zones, classify by destination IP only because the firewall can’t scale to hold the internet routing table.Apply DoS Protection only to critical devices, especially popular attack targets that users access from the internet, such as web servers and database servers.
- For existing sessions,
- Security Policy rulesaffect both the ingress and egress flows of a session. To establish a session, incoming traffic must match an existing Security policy rule. If there is no match, the firewall discards the packet. A Security policy allows or denies traffic between zones (interzone) and within zones (intrazone) using criteria including zones, IP addresses, users, applications, services, and URL categories.The default Security policy rules don’t permit traffic to travel between zones, so you need to configure a Security policy rule if you want to allow interzone traffic. All intrazone traffic is allowed by default. You can configure Security policy rules to match and control intrazone, interzone, or universal (intrazone and interzone) traffic.Zone Protection profiles, DoS Protection profiles and policy rules, and Security policy rules only affect dataplane traffic on the firewall. Traffic originating on the firewall management interface does not cross the dataplane, so the firewall does not match management traffic against these profiles or policy rules.
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