A FIN flood sends TCP FIN packets for connections that were never established, aiming to consume the processing resources normally spent tearing down real sessions.
Written for business and infrastructure decision-makers, not protocol engineers.
A FIN packet normally signals that one side of a TCP connection is done sending data and wants to close gracefully. During a FIN flood, attackers send large volumes of FIN packets that don't correspond to any tracked connection, forcing receiving systems to check connection-tracking state for traffic that will never resolve to anything real.
Each request has to be looked up against a sales record before it can be rejected. If enough bogus return requests arrive at once, real returns get delayed. A FIN flood applies the same pressure to connection-teardown processing.
Availability risk that belongs in business-continuity planning.
Availability risk that belongs in business-continuity planning.
Availability risk that belongs in business-continuity planning.
Availability risk that belongs in business-continuity planning.
FIN-based floods matter because connection teardown, like handshake setup, touches shared state-tracking infrastructure. A defense tuned too aggressively risks dropping legitimate session closes, which is why FIN validation is typically deployed selectively rather than everywhere by default.
Attacks against one customer can become an infrastructure and service-quality issue.
Availability, latency and shared network resources are immediately visible to end users.
If users cannot connect, they cannot transact, work or consume the service they pay for.
NeuroWall verifies FIN packets against tracked TCP state before honoring them. The module is off by default to avoid false positives on legitimate teardown traffic, and tunable per deployment where it's needed.
Book a Demo →A FIN flood sends large volumes of TCP FIN packets that don't correspond to any tracked connection, aiming to consume connection-teardown processing resources.
A FIN flood by itself targets processing capacity rather than specific sessions. Forged control packets aimed at closing a specific real connection are closer to an RST-based attack.
Overly aggressive FIN validation risks misclassifying legitimate connection closes as attack traffic. It's enabled selectively where the deployment's traffic patterns are well understood.
It can be. When distributed sources generate the traffic simultaneously, it is a distributed denial-of-service attack.
Yes. NeuroWall verifies FIN packets against tracked connection state as part of its DDoS protection capabilities.