Stream exception policy options in your AWS Network Firewall firewall policy - AWS Network Firewall

Stream exception policy options in your AWS Network Firewall firewall policy

The firewall policy's stream exception policy setting determines how Network Firewall handles traffic when a network connection breaks midstream. Network connections can break due to disruptions in external networks or within the firewall itself. A stream exception policy presents the following options:

  • Drop - Network Firewall fails closed and drops all subsequent traffic going to the firewall. This is the default behavior.

  • Continue - Network Firewall continues to apply rules to the subsequent traffic without context from traffic before the break. This impacts the behavior of rules that depend on this context. For example, if you have a stateful rule to drop httptraffic, Network Firewall won't match the traffic for this rule because the service won't have the context from session initialization defining the application layer protocol as HTTP. However, this behavior is rule dependent—a TCP-layer rule using a flow:stateless rule would still match, as would the aws:drop_strict default action.

  • Reject - Network Firewall fails closed and drops all subsequent traffic going to the firewall. Network Firewall also sends a TCP reject packet back to your client so that the client can immediately establish a new session. Network Firewall will have context about the new session and will apply rules to the subsequent traffic.