An ACK flood sends acknowledgement packets that don't correspond to any real connection. Each packet looks ordinary on its own — the danger is in the volume, which can quietly consume state-tracking resources across firewalls and servers.
Written for business and infrastructure decision-makers, not protocol engineers.
In a normal TCP exchange, an ACK confirms data already received on an established connection. During an ACK flood, attackers send large volumes of ACK packets with no matching connection, forcing receiving systems to spend cycles checking connection state for traffic that was never legitimate.
Staff have to check every confirmation against a shipping log before they can discard it. If enough fake confirmations arrive at once, the mailroom falls behind on real deliveries. An ACK flood works the same way against connection-tracking systems.
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.
ACK floods are a long-standing DDoS technique precisely because a single ACK packet is indistinguishable from legitimate traffic without checking it against actual connection state — a low-cost attack technique that trades attacker effort for defender inspection cost.
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 validates ACKs against tracked connection state at the XDP layer. The module is off by default and enabled for gateway deployments with predictable session patterns, so legitimate ACKs on established sessions are never affected.
Book a Demo →An ACK flood sends large volumes of TCP acknowledgement packets that don't correspond to any real, tracked connection, aiming to consume state-tracking resources on firewalls and servers.
A SYN flood targets the connection backlog during handshake setup. An ACK flood targets systems that must check incoming ACKs against already-established connection state.
Yes. Shared network infrastructure sitting in the traffic path can be strained by the volume of state lookups, even if it isn't the intended target.
It can be. When distributed sources generate the traffic simultaneously, it is a distributed denial-of-service attack.
Yes. NeuroWall validates ACKs against tracked connection state as part of its DDoS protection capabilities.