A SYN flood overwhelms internet-facing systems with connection requests that are deliberately left incomplete. The objective is usually not to steal data — it is to make legitimate customers struggle to connect.
Written for business and infrastructure decision-makers, not protocol engineers.
SYN is the first step in establishing many TCP connections. During a SYN flood, attackers generate large numbers of connection requests without completing the process. Enough incomplete requests can exhaust connection-handling resources or contribute to network overload.
A caller asks for a room, the receptionist checks availability and waits for confirmation — but the caller disappears. Repeat that thousands of times. Staff are overwhelmed and genuine guests cannot get through. A SYN flood follows the same idea: huge numbers of connections are started but never completed.
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.
In September 1996, New York ISP Panix suffered a widely publicized SYN flood outage. The incident became one of the early cases that pushed the industry to improve SYN-flood defenses. The technique remains relevant because internet services still need to accept new connections.
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 runs a dedicated SYN flood module, benchmarked sustaining ~96K PPS with 375,000 policies loaded and the system still responsive — legitimate handshakes complete normally while excess SYNs are dropped before they occupy a backlog slot.
Book a Demo →A SYN flood sends large numbers of TCP connection requests without completing the connection process, attempting to consume resources and prevent legitimate users from connecting.
SYN is the TCP signal used to initiate a connection.
It is a connection whose setup has started but has not finished.
It can be. When many distributed systems generate the traffic simultaneously, it is a distributed denial-of-service attack.
Yes. NeuroWall helps protect networks and internet-facing services against SYN flood attacks as part of its DDoS protection capabilities.